2008. "Chemisorption-Induced Structural Changes and Transition from Chemisorption to Physisorption in Au6(CO)n-(n=4-9)." Journal of Physical Chemistry C 112(31):11920-11928. doi:10.1021/jp803161b Abstract The interactions of CO with gold clusters are essential to understanding the catalytic mechanisms of CO oxidation on supported gold nanoparticles. Here we report a photoelectron spectroscopy and theoretical study of CO adsorption on a well-defined Au6− cluster in Au6(CO)n− (n = 4-9). Previous studies have shown that the first three CO successively bind the three apex sites of the triangular Au6−. The current work reveals that the forth CO induces a major structural change to create more apex sites to accommodate the additional CO. Definitive spectroscopic evidence is obtained for the chemisorption saturation at Au6(CO)6 −, in which Au6 has rearranged to accommodate the six CO adsorbates. The photoelectron spectra of larger clusters from Au6(CO)7 − to Au6(CO)9 − are observed to be almost identical to that of Au6(CO)6 −, suggesting that the additional CO’s are simply physisorbed onto the Au6(CO)6 − core. Quasirelativistic density functional calculations are performed on both Au6(CO)n and Au6(CO)n − (n = 4-6). The theoretical results are used to interpret the experimental observations and provide insight into the nature of CO interactions with gold clusters. The Au6 cluster is shown to be highly fluxional upon multiple CO adsorptions, stabilizing structures with more apex sites to accommodate the additional CO’s. The CO-induced structural transformation is analogous to structural flexibility and mobility in heterogeneous catalysis. The observations of the propensity of CO toward apex sites and CO-induced structural changes in small gold clusters m
2008. "Low-Lying Isomers of the B9- Boron Cluster: The Planar Molecular Wheel Versus Three-Dimensional Structures." Journal of Chemical Physics 129(2):187-193. Article number: 024302. doi:10.1063/1.2948405 Abstract The B9- cluster was found previously to be an unprecedented molecular wheel containing an octacoordinate planar boron with D8h symmetry in a combined photoelectron spectroscopy (PES) and theoretical study [H. J. Zhai et al., Angew. Chem. Int. Ed. 42, 6004 (2003)]. However, the PES spectra of B9- exhibit minor features that cannot be explained by the global minimum D8h structure, suggesting possible contributions from low-lying isomers at finite temperatures. Here we present Car-Parrinello molecular dynamics with simulated annealing simulations to fully explore the potential energy surface of B9- and search for low-lying isomers that may account for the minor PES features. We performed density functional theory (DFT) calculations with different exchange-correlation functionals and ab initio calculations at various levels of theory with different basis sets. Two three-dimensional low-lying isomers were found, both of Cs symmetry, 6.29 (Cs-2) and 10.23 (Cs-1) kcal/mol higher in energy than the D8h structure at the highest CCSD(T) level of theory. Calculated detachment transitions from the Cs-2 isomer are in excellent agreement with the minor features observed in the PES spectra of B9-. The B9- cluster proves to be a challenge for most DFT methods and the calculated relative energies strongly depend on the exchange-correlation functionals, providing an excellent example for evaluating the accuracies of various DFT methods.
2008. "Correlation of Calculated Excited-state Energies and Experimental Quantum Yields of Luminescent Tb(III) β-diketonates." Journal of Physical Chemistry A 112(20):4527-4530. doi:10.1021/jp8002799 Abstract Theoretical calculations employing time dependent density functional theory (TDDFT) are used to characterize the excited states of Tb(III) β-diketonate complexes. Calculated results are compared directly with experimental results that together show a correlation between relative quantum yields and the excited-state energies that depend on the electronic properties of the p,p’- substituent group associated with the coordinating N-donor neutral ligand. It is found that changes in the electron donating nature of the neutral ligand structure leads to shifts in the lowest triplet energy level of the complex that consequently changes the relative quantum yield. Thus providing critical direction for the synthesis of high quantum yield terbium complexes.
2007. "On The Chemical Bonding of Gold In Auro-Boron Oxide Clusters AunBO-(n=1-3)." Journal of Physical Chemistry A 111(9):1648-1658. doi:10.1021/jp0657437 Abstract During experiment on Au-B alloy clusters, an auro-boron oxide cluster Au2BO- was observed to be an intense peak dominating the Au-B mass spectra, along with weaker signals for AuBO- and Au3BO-. Well-resolved photoelectron spectra have been obtained for the three new oxide clusters, which exhibit an odd-even effect in their electron binding energies. Au2BO- is shown to be a closed shell molecule with a very high electron binding energy, whereas AuBO and Au3BO neutrals are shown to be closed shell species with large HOMO-LUMO gaps, resulting in relatively low electron affinities. Density functional calculations were performed for both AunBO- (n = 1-3) and the corresponding HnBO- species in order to evaluate the analogy in bonding between gold and hydrogen in B-Au clusters. The combination of experiment and theory allowed us to establish the structures and chemical bonding of these tertiary clusters. We find that the first gold atom does mimic hydrogen and interacts with the BO unit to produce a linear AuBO- structure. This unit preserves its identity when interacting with additional gold atoms: a linear Au-[AuBO] complex is formed when adding one extra Au atom and two isomeric Au2-[AuBO] complexes are formed when adding two extra Au atoms. Since BO- is isoelectronic to CO, the AunBO- species can be alternatively viewed as Aun interacting with a BO- unit. The structures and chemical bonding in AunBO- are compared to those in the corresponding AunCO complexes.
2007. " Basis Set Exchange: A Community Database for Computational Sciences ." Journal of Chemical Information and Modeling 47(3):1045-1052. doi:10.1021/ci600510j Abstract Basis sets are one of the most important input data for computational models in the chemistry, materials, biology and other science domains that utilize computational quantum mechanics methods. Providing a shared, web accessible environment where researchers can not only download basis sets in their required format, but browse the data, contribute new basis sets, and ultimately curate and manage the data as a community will facilitate growth of this resource and encourage sharing both data and knowledge. We describe the Basis Set Exchange (BSE), a web portal that provides advanced browsing and download capabilities, facilities for contributing basis set data, and an environment that incorporates tools to foster development and interaction of communities. The BSE leverages and enables continued development of the basis set library originally assembled at the Environmental Molecular Sciences Laboratory.
2007. "Isomers and Conformers of H(NH₂BH₂)(n)H Oligomers: Understanding the Geometries and Electronic Structure of Boron-Nitrogen-Hydrogen Compounds as Potential Hydrogen Storage Materials." Journal of Physical Chemistry C 111(8):3294-3299. doi:10.1021/jp066360b Abstract Boron-nitrogen-hydrogen (BNHx) materials are polar analogs of hydrocarbons with potential applications as media for hydrogen storage. As H(NH₂BH₂)nH oligomers result from dehydrogenation of NH₃BH₃ and NH₄BH₄ materials, understanding the geometries, stabilities, and electronic structure of these oligomers is essential for developing chemical methods of hydrogen release and regeneration of the BNHx-based hydrogen storage materials. In this work we have performed computational modeling on the H(NH₂BH₂)nH (n = 1 – 6) oligomers using density functional theory (DFT). We have investigated linear chain structures and the stabilizing effects of coiling, biradicalization, and branching through Car-Parrinello molecular dynamics simulations and geometry optimizations. We find that the zig-zag linear oligomers are unstable with respect to the coiled, square-wave chain, and branched structures, with the coiled structures being the most stable. Dihydrogen bonding in oligomers, where protic Hδ⁺(N) hydrogens interact with hydridic Hδ⁻(B) hydrogens, plays a crucial role in stabilizing different isomers and conformers. The results are consistent with structures of products that are seen in experimental NMR studies of dehydrogenated ammonia borane.
2007. "Au34-: A Fluxional Core-Shell Cluster." Journal of Physical Chemistry C 111(23):8228-8232. doi:10.1021/jp071960b Abstract Among the large Aun – clusters for n > 20, the photoelectron spectra of Au34 – exhibit the largest energy gap (0.94 eV) with well-resolved spectral features, making it a good candidate for structural consideration in conjunction with theoretical studies. Extensive structural searches at several levels of theory revealed that the low-lying isomers of Au34 – can be characterized as fluxional core-shell type structures with 4 or 3 inner atoms and 30 or 31 outer atoms, i.e., Au4@Au30 – and Au3@Au31 –, respectively. Detailed comparisons between theoretical and photoelectron results suggest that the most probable ground state structures of Au34 – are of the Au4@Au30 – type. The 30 outer atoms seem to be disordered or fluxional, giving rise to a number of low-lying isomers with very close energies and simulated photoelectron spectra. The fluxional nature of the outer layer in large gold clusters or nanoparticles may have important implications for their remarkable catalytic activities.
2007. "Endohedral Stannaspherenes M@Sn12-: A Rich Class of Stable Molecular Cage Clusters." Angewandte Chemie International Edition 46(5):742-745. doi:10.1002/anie.200603226 Abstract Experimental and theoretical evidence is reported that the icosahedral stannaspherene Sn12 2- cage can trap an atom from any of the transition-metal series or the f-elements, giving rise to a myriad of stable endohedral clusters. A selected set of M@Sn12 - cluster has been created using laser vaporization and characterized by photoelectron spectroscopy. It is shown that these clusters maintain perfect or pseudo-icosahedral symmetry with the central metal atom inducing very little distortion to the stannaspherene cage. The doped atom in M@Sn12 - keeps its quasiatomic nature with large magnetic moments. The endohedral stannaspherenes might thus be viewed as “superatoms”, yielding potentially a rich class of new building blocks for clusterassembled materials with tunable magnetic, electronic, and chemical properties.
2006. "Potential Application of Kläui Ligands in Actinide Separations." Chapter 13 in Separations for the Nuclear Fuel Cycle in the 21st Century, ACS Symposium Series, vol. 933, ed. Gregg J Lumetta, et al. , pp. 201-218. American Chemical Society, Washington, DC. Abstract We have undertaken a systematic study of the complexation of Cp*Co[P(O)(OR)2]3- (Cp* = pentamethylcyclopentadienyl) ligands with f-block metal ions (i.e., lanthanides and actinides). As part of this work, the complexation of La3+ ion with Cp*Co[P(O)(OR)2]3- ligands has been studied as the alkyl group was systematically varied from methyl to n-propyl (R = -CH3, -CH2CH3, and -CH2 CH2CH3). For ligands in which R = -CH3 or -CH2CH3, complexes with ligand-to-La stoichiometries of 1:1 and 2:1 were formed. In contrast, only the 1:1 complex was isolated when R = CH2CH2CH3. A prototypical extraction chromatography resin containing Cp*Co[P(O)(OEt)2]3- (1b) has been prepared. The resin consists of 0.75 wt% 1b on Amberlite® XAD-7. This resin strongly sorbs Am3+ and Pu4+. The sorption of these ions decreases with increasing nitric acid concentration, but this effect is more pronounced for Am3+. This allows for convenient separation of Am3+ from Pu4+ by simple adjustments in the HNO3 concentration. The tripodal geometry of 1b disfavors the complexation of UO22+, so sorption of U(VI) by the 1b-containing resin is weak.
2006. "Theoretical Studies of the Electronic Structure of the Compounds of the Actinide Elements." Chapter 17 in The Chemistry of the Actinide and Transactinide Elements, vol. 3, ed. Morss, LR; Edelstein, NM; Fuger, J; Katz, JJ, pp. 1893-2012. Springer, Dordrecht, Netherlands. Abstract In this chapter, we will present an overview of the theoretical and computational developments that have increased our understanding of the electronic structure of actinide‐containing molecules and ions. The application of modern electronic structure methodologies to actinide systems remains one of the great challenges in quantum chemistry; indeed, as will be discussed below, there is no other portion of the periodic table that leads to the confluence of complexity with respect to the calculation of ground‐ and excited‐state energies, bonding descriptions, and molecular properties. But there is also no place in the periodic table in which effective computational modeling of electronic structure can be more useful. The difficulties in creating, isolating, and handling many of the actinide elements provide an opportunity for computational chemistry to be an unusually important partner in developing the chemistry of these elements. The importance of actinide electronic structure begins with the earliest studies of uranium chemistry and predates the discovery of quantum mechanics. The fluorescence of uranyl compounds was observed as early as 1833 (Jørgensen and Reisfeld, 1983), a presage of the development of actinometry as a tool for measuring photochemical quantum yields. Interest in nuclear fuels has stimulated tremendous interest in understanding the properties, including electronic properties, of small actinide‐containing molecules and ions, especially the oxides and halides of uranium and plutonium. The synthesis of uranocene in 1968 (Streitwieser and Mu¨ ller‐Westerhoff, 1968) led to the flurry of activity in the organometallic chemistry of the actinides that continues today. Actinide organometallics (or organoactinides) are nearly always molecular systems and are often volatile, which makes them amenable to an arsenal of experimental probes of molecular and electronic structure (Marks and Fischer, 1979). Theoretical and computational studies of the electronic structure of actinide systems have developed in concert with the experimental studies, and have been greatly facilitated by the extraordinary recent advances in high‐performance computational technology. We will focus on computational studies of the electronic structure of discrete (molecular or ionic) actinide‐containing systems. We begin by discussing some of the general tenets of bonding that are relevant to the actinide elements and some of the challenges that are unique to this field. We then present the results of computational electronic structure studies on a variety of molecular actinide systems. The literature of molecular electronic structure of actinide systems has been compiled by Pyykko¨ (1986, 1993, 2001), as well as being available as a database on the web (http://www.csc.fi/rtam). Pepper and Bursten (1991) reviewed the methodology and applications in the field in 1991. The reader is referred to those reviews for some of the details on earlier studies in this field. We restrict our discussion in this chapter to molecular actinide systems and do not discuss the extensive body of research in the use of theoretical electronic structure methods to model solid‐state actinide chemistry. The reader is referred to Chapter 21 and some recent review articles (Lander et al., 1994; Soderlind, 1998; Wills and Eriksson, 2000) for discussions of theoretical electronic structure methods applied to the metallic actinide elements and solid‐state actinide compounds. We will also have minimal discussion of compounds of the transactinide elements in this chapter. The electronic structure of compounds of the transactinides is discussed in Chapter 14 and in the excellent review by Pershina (1996).
2006. "Theoretical Probing of Deltahedral Closo-AuroBoranes BxAux2⁻(x = 5-12)." Inorganic Chemistry 45(14):5269-5271. doi:10.1021/ic060615i Abstract Since the discovery of boron hydrides (boranes) by Stock in 1912, these compounds have played a major role in advancing chemical bonding theory beyond the classical idea of two-center two-electron bonds. Longuet-Higgins and Lipscomb et al. first put forward the concept of three-center two-electron bonding to explain the structures of all known boron hydrides, in which the bridging B-H-B bond appeared to be the key structural unit. This represents a milestone in establishing the validity of the molecular orbital theory.
2006. "Experimental and Theoretical Investigations of IR Spectra and Electronic Structures of the U(OH)₂, UO₂(OH), and UO₂(OH)₂ Molecules." Inorganic Chemistry 45(10):4157-4166. Abstract Reactions of laser-ablated U atoms and H₂O₂ molecules produce UO₂, H₂UO₂, and UO₂(OH)₂ as major products and U(OH)₂ and HU(O)OH as minor products. Complementary information is obtained from similar reactions of U atoms with D₂O₂, with H₂+O₂ mixtures, and with water in excess argon. Through extensive relativistic density functional theory (DFT) calculations we have determined the geometry structures and ground states of these uranium species with a variety of oxidation states U(II), U(IV), U(V), and U(VI). The calculated vibrational frequencies, infrared (IR) intensities, and isotopic frequency ratios are in good agreement with the experimental values, thus supporting assignments of the observed matrix IR spectra. We propose that the reactions proceed by forming an energized [U(OH)₄]* intermediate from reactions of the excited U atom with two H₂O₂ molecules. Due to the special stability of the U(VI) oxidation state this intermediate decomposes to the UO₂(OH)₂ molecule, which reveals a distinctive difference between the chemistries of uranium and thorium, where the major product in analogous thorium reactions is the tetrahedral Th(OH)₄ molecule owing to the stable Th(IV) oxidation state.
2006. "On The Structure and Chemical Bonding of Tri-Tungsten Oxide Clusters W3On- and W3On (n=7-10): W3O8 As A Potential Molecular Model for O-Deficient Defect Sits in Tungsten Oxides." Journal of Physical Chemistry A 110(1):85-92. doi:10.1021/jp055325m Abstract Electronic and structural properties of a series of tri-tungsten oxide clusters, W3On- and W3On (n = 7-10), are investigated using photoelectron spectroscopy and density functional theory (DFT) calculations. Both W 5d and O 2p detachment features are observed for n = 7-9, whereas only detachment features from O 2p type orbitals are observed for W3O10- at high electron binding energies (>7 eV). A HOMO-LUMO gap (~3.4 eV) is observed for the stoichiometric W3O9 cluster, which already reaches the bulk value, suggesting that W3O9 can be viewed as the smallest molecular model for bulk WO3. DFT calculations are carried out to locate the most stable structures for both the anion and neutral clusters; time-dependent DFT method is used to predict the vertical detachment energies and to compare with the experimental data. It is shown that W3O9 possesses a D3h structure, in which each W atom is tetrahedrally coordinated with two bridging O atoms and two terminal O atoms. W3O8 and W3O7 can be viewed as removing one and two terminal O atoms from W3O9, respectively, whereas W3O10 can be viewed as replacing a terminal O in W3O9 by a peroxo O2 unit. We show that W3O8 contain a localized W4+ site, which can readily react with O2 to form the W3O10 clusters with a calculated O2 adsorption energy of -78 kcal/mol. It is suggested that the W3O8 cluster can be viewed as a molecular model for O-deficient site in tungsten oxides.
2006. "Experimental and Theoretical Characterization of Superoxide Complexes [W₂O₆(O₂⁻)] and [W₃O₉₋(O₂⁻)]: Models for the Interaction of O₂ with Reduced W Sites on Tungsten Oxide Surfaces." Angewandte Chemie International Edition 45(4):657-660. doi:10.1002/anie.200503652 Abstract Two O-rich tungsten oxide clusters, W2O8- and W3O11-, were produced and investigated by photoelectron spectroscopy and density functional theory calculations. The two anions are best considered as W2O6(O2-) and W3O9(O2-), respectively, each containing a side-on bound superoxide ligand, whereas the neutral clusters W2O8 and W3O11 are shown to involve O2 physisorbed to the W2O6 or W3O9 stoichiometric cluster. The current study indicates that the extra electron in W2O6- and W3O9- are capable of activating dioxygen by non-dissociative electron transfer (W 5d - O2 -*), and the two anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.
2006. "The OH Radical-H2O Molecular Interaction Potential." Journal of Chemical Physics 124:224318 (15). doi:10.1063/1.2200701 Abstract The OH radical is one of the most important oxidants in the atmosphere due to its high reactivity. The study of hydrogen-bonded complexes of OH with the water molecules is a topic of significant current interest. In this work, we present the development of a new analytical functional form for the interaction potential between rigid OH radical and H2O molecules. To do this we fit a selected functional form to a set of high level ab initio data. Since there are low-lying excited states for the H2O•OH complex, the impact of the excited states on the chemical behavior of the OH radical can be very important. We perform a Potential Energy Surface (PES) scan using the CCSD(T)/aug-cc-pVTZ level of electronic structure theory for both excited and ground states. To model the physics of the unpaired electron in the OH radical, we develop a tensor polarizability generalization of the Thole Type all-atom polarizable rigid potential for the OH radical, which effectively describes the interaction of OH with H2O for both ground and excited states. The stationary points of (H2O)n•OH clusters were identified as a benchmark of the potential. Battelle operated PNNL for the USDOE.
2006. "Sn₁₂²⁻: Stannaspherene." Journal of the American Chemical Society 128(26):8390-8391. doi:10.1021/ja062052f Abstract The Sn₁₂²⁻ cluster is discovered to be a highly stable and highly symmetric icosahedral cage bonded by four delocalized radial π bonds and nine delocalized onsphere bonds from the 5p orbitals of the Sn atoms. It has a diameter of 6.1 Å with a large empty interior volume and can host most transition metal atoms inside, giving rise to a large class of endohedral chemical building blocks for cluster-assembled nanomaterials.
2006. "Pb-12(2-): Plumbaspherene." Journal of Physical Chemistry A 110(34):10169-10172. Abstract Photoelectron spectroscopy and theoretical calculations show that Pb122- is a highly stable icosahedral cage cluster, similar to Sn122-. It is bonded by four delocalized radial bonds and nine delocalized on-sphere bonds from the 6p orbitals of the Pb atoms. Following Sn122- (stannaspherene), we coin a name, plumbaspherene, for the highly stable and nearly spherical Pb122- cluster, which has a diameter of ~6.3 Å with an empty interior volume large enough to host most transition metal atoms and afford a new class of stable endohedral plumbaspherenes similar to the endohedral fullerenes.
2005. "Electronic Structure Differences in ZrO2 vs. HfO2." Journal of Physical Chemistry A 109(50):11521-11525. Abstract While ZrO2 and HfO2 are, for the most part, quite similar chemically, subtle differences in their electronic structures appear to be responsible for differing MO2/Si (M = Zr, Hf) interface stabilities. In order to shed light on the electronic structure differences between ZrO2 and HfO2, we have conducted joint experimental/theoretical studies. Since electron affinities are a sensitive probe of electronic structure, we have measured them by conducting photoelectron spectroscopic experiments on ZrO2- and HfO2-. The electron affinity of HfO2 was determined to be 2.14 0.03 eV, while that of ZrO2 was determined to be 1.64 0.03 eV. Concurrently, electronic structure calculations were conducted to determine electron affinities, vibrational frequencies, and geometries of these systems. The calculated electron affinities of HfO2 and ZrO2 were found to be 2.05 and 1.62 eV, respectively. The molecular results confirm earlier predictions from solid phases that HfO2 is more ionic than ZrO2. The excess electron in MO2- occupies an sd-type hybrid orbital localized on the M atom (M=Zr, Hf). The structural parameters of ZrO2 and HfO2 were found to be very similar. The difference in geometries between the neutral and the anion is along the symmetrical stretching and bending modes. Together, these studies unveil significant differences in the electronic structures of ZrO2 and HfO2.
2005. "Unique CO Chemisorption Properties of Gold Hexamer: Au₆(CO)n⁻(n = 0-3)." Journal of the American Chemical Society 127(34):12098-12106. Abstract Elucidating the chemisorption properties of CO on gold clusters is essential to understanding the catalytic mechanisms of gold nanoparticles. The gold hexamer Au₆ is a highly stable cluster, which is known to possess a D₃h triangular ground state structure with an extremely large HOMO-LUMO gap. Here we report a photoelectron spectroscopy (PES) and quasi-relativistic density functional theory (DFT) study of Au₆-CO complexes, Au₆(CO)n⁻ and Au₆(CO)n (n = 0-3). CO chemisorption on Au₆ was observed to be highly unusual. While the electron donor capability of CO is known to decrease the electron binding energies of Aum(CO)n⁻ complexes, CO chemisorption on Au₆ was observed to have very little effect on the electron binding energies of the first PES band of Au₆(CO)n⁻ (n = 1-3). However, the second PES band is significantly red-shifted upon successive CO chemisorption, resulting in a rapid closing of the HOMO-LUMO energy gap from 2.30 eV in Au₆ to 1.72, 1.45, and 1.17 eV for Au₆(CO)n (n = 1-3), respectively. Extensive DFT calculations showed that the first three CO successively chemisorb to the three apex atoms of the D₃h Au₆. It is shown that the LUMO (6a₁’) and LUMO+1 (8e’) of Au₆ are energetically near-degenerate, which are well separated from the HOMO (7e’), giving rise to the unusually large HOMO-LUMO gap in Au₆. Upon CO chemisorption, the degeneracy of the HOMO and LUMO orbitals are both lifted, leading to a₁+b₂ components under C₂v symmetry. In the Au₆(CO)n complexes, one of the a₁+ b₂ components of the LUMO+1 orbital, which mainly involves the inner triangle of the Au₆ motif, becomes the LUMO. Thus CO chemisorption on the apex Au sites (outer triangle) has little effect on this orbital, resulting in the roughly constant electron binding energies for the first PES band in Au₆(CO)n⁻ (n = 0-3). On the other hand, the a₁+b₂ components of the HOMO of Au₆ are significantly destabilized through HOMO-LUMO mixing in Au₆ and electron donation from the 5σ orbital of CO, resulting in the smaller HOMO-LUMO gaps observed in the Au₆(CO)n complexes.
2005. "Electronic and Structural Evolution and Chemical Bonding in Ditungsten Oxide Clusters: W₂On⁻ and W₂On (n = 1-6)." Journal of Physical Chemistry A 109(27):6019-6030. Abstract We report a systematic and comprehensive investigation of the electronic structures and chemical bonding in a series of ditungsten oxide clusters, WOn⁻ and WOn (n = 1-6), using anion photoelectron spectroscopy and density functional theory (DFT) calculations. Well-resolved photoelectron spectra were obtained at several photon energies (2.331, 3.496, 4.661, 6.424, and 7.866 eV) and W 5d-based spectral features were clearly observed and distinguished from O 2p-based features. More complicated spectral features were observed for the oxygen-deficient clusters due to the W 5d electrons. With increasing oxygen content in WOn⁻, the photoelectron spectra were observed to shift gradually to higher binding energies, accompanied by a decreasing number of W 5d-derived features. A behavior of sequential oxidation as a result of charge transfers from W to O was clearly observed. A large energy gap (2.8 eV) was observed in the spectrum of WO₆⁻, indicating the high electronic stability of the stoichiometric WO₆ molecule. Extensive DFT calculations were carried out to search for the most stable structures of both the anion and neutral clusters. Time-dependent DFT method was used to compute the vertical detachment energies and compare to the experimental data. Molecular orbitals were used to analyze the chemical bonding in the ditungsten oxide clusters and elucidate their electronic and structural evolution.
2005. "Reactions of Laser-Ablated Uranium Atoms with H₂O in Excess Argon: A Matrix Infrared and Relativistic DFT Investigation of Uranium Oxyhydrides ." Inorganic Chemistry 44(7):2159-2168. doi:10.1021/ic0483951 Abstract Laser-ablated U atoms react with H₂O during condensation in excess argon. Infrared absorptions at 1416.3, 1377.1, and 859.4 cm⁻¹ are assigned to symmetric H-U-H, antisymmtric H-U-H, and U=O stretching vibrations of the primary reaction product H₂UO. Uranium monoxide, UO, also formed in the reaction, inserts into H₂O to produce HUO(OH), which absorbs at 1370.5, 834.3, and 575.7 cm⁻¹. The HUO(OH) uranium(IV) product undergoes ultraviolet photoisomerization to a more stable H₂UO₂ uranium(VI) molecule, which absorbs at 1406.4 and 885.9 cm⁻¹. The addition of another water molecule to either HUO(OH) or H₂UO₂ produces H₂UO(OH)₂. Several of these species, particularly H₂UO₂, appear to form Ar coordinated complexes. The predicted vibrational frequencies, relative absorption intensities, and isotopic shifts from relativistic DFT calculations are in good agreement with observed spectra, which further support the identification of novel uranium oxyhydrides from matrix infrared spectra.
2005. "157 nm Pellicles (Thin Films) for Photolithography: Mechanistic Investigation of the VUV and UV-C Photolysis of Fluorocarbons." Journal of the American Chemical Society 127(23):8320-8337. doi:10.1021/ja0440654 Abstract The use of 157 nm as the next lower wavelength for photolithography for the production of semiconductors has created a need for transparent and radiation-durable polymers for use in soft pellicles, the polymer films which protect the chip from particle deposition. The most promising materials for pellicles are fluorinated polymers, but currently available fluorinated polymers undergo photodegradation and/or photodarkening upon long term exposure to 157 nm irradiation. To understand the mechanism of the photodegradation and photodarkening of fluorinated polymers, mechanistic studies on the photolysis of liquid model fluorocarbons, including perfluorobutylethyl ether and perfluoro-2 H-3-oxa-heptane, were performed employing UV, NMR, FTIR, GC, and GC/MS analyses. All hydrogen-containing compounds showed decreased photostability compared to the fully perfluorinated compounds. Irradiation in the presence of atmospheric oxygen showed reduced photostability compared to deoxygenated samples. Photolysis of the samples was performed at 157, 172, 185, and 254 nm and showed only minor wavelength dependence. Mechanisms for photodegradation of the fluorocarbons are proposed, which involve Rydberg excited states. Time-dependent density functional theory has been used to predict the excitation spectra of model compounds.
2005. "Experimental and Theoretical Investigation of the Electronic and Geometrical Structures of the Special Au₃₂ Cluster ." Angewandte Chemie International Edition 44(43):7119-7123. doi:10.1002/anie.200502795 Abstract Photoelectron spectroscopy and theoretical calculations are used to elucidate the structure of the Au₃₂ - cluster. Although density functional calculations suggest that the high symmetry Ih cage structure of Au₃₂ remains to be the lowest in energy for Au₃₂ - at 0 K, the calculated photoelectron spectrum of a low-lying amorphous structure (C₁) is found to agree best with the experiment. Free energy calculations show that the C₁ structure becomes the most stable isomer at higher temperatures, indicating the importance of entropy in determining the stability of clusters at finite temperatures.
2005. "Experimental and Theoretical Investigation of the Electronic and Geometrical Structures of the Au₃₂ Cluster." Angewandte Chemie International Edition 44(43):7119-7123. doi:10.1002/anie.200502795 Abstract Photoelectron spectroscopy and theoretical calculations are used to elucidate the structure of the Au₃₂- cluster. Although density functional calculations suggest that the high symmetry Ih cage structure of Au₃₂ remains to be the lowest in energy for Au₃₂- at 0 K, the calculated photoelectron spectrum of a low-lying amorphous structure (C1) is found to agree best with the experiment. Free energy calculations show that the C1 structure becomes the most stable isomer at higher temperatures, indicating the importance of entropy in determining the stability of clusters at finite temperatures.
2004. "Toward the Solution Synthesis of the Tetrahedral Au₂₀ Cluster." Journal of Physical Chemistry B 108(33):12259-12263. Abstract We report solution synthesis of the recently discovered tetrahedral Au₂₀ cluster coordinated with eight PPh₃ (Ph = Phenyl) ligands. The composition and molecular weight of the Au₂₀ ( PPh₃)₈ complex were confirmed by the isotopic pattern of its doubly charged cation using high resolution mass spectrometry. Collision-induced dissociation experiment showed that four PPh₃ can be easily dissociated from Au₂₀ ( PPh₃)₈²⁺, resulting in a highly stable Au₂₀ ( PPh₃)₄²⁺ molecule. This observation is consistent with the tetrahedral structure, in which the four apex sites are expected to be strongly bound to the PPh₃ ligands, and is confirmed by theoretical calculations, which predicted a highly stable Au₂₀ (PH₃)₄ complex with Au-PH₃ bond energies of ~1 eV. The current experimental and theoretical observations suggest that large quantity of ligand-stabilized tetrahedral Au₂₀ can be obtained, opening the door for exploring its anticipated novel chemical, optical, and catalytical properties.
2004. "Icosahedral Gold Cage Clusters: M@Au-12 (M=V, Nb, and Ta)." Journal of Chemical Physics 121(17):8369-8374. Abstract Gold clusters and nanoparticles have become an active research field lately because of the discovery of remarkable catalytic properties of nanogold and their potential applications in nanoelectronics, nanosensors, and as biological markers. The chemistry of gold is dominated by the strong relativistic effects and the so-called aurophilic attraction, leading to highly unusual structures for gold clusters and compounds relative to those for copper and silver. One of the most interesting findings has been the planar gold cluster anions with more than ten atoms. These unique planar cluster anions were experimentally discovered using ion mobility, interpreted on the basis of the strong relativistic effects of Au, and were further confirmed by a joint photoelectron spectroscopy (PES) and density-functional theory (DFT) study. Among other exciting discoveries in elemental gold clusters include the tetrahedral Au20 cluster and the golden fullerene Au32 cage cluster reported recently.
2004. "Icosahedral Gold Cage Clusters: M@Au₁₂⁻ (M = V, Nb, and Ta)." Journal of Chemical Physics 121(17):8369-8374. Abstract We report the observation and characterization of a series of stable bimetallic 18-valence-electron clusters containing a highly symmetric 12-atom icosahedral Au cage with an encapsulated central heteroatom of group VB transition metals, M@Au₁₂⁻ (M = V, Nb, Ta). Electronic and structural properties of these clusters were probed by anion photoelectron spectroscopy and theoretical calculations. Characteristics of the M@Au₁₂⁻ species include their remarkably high binding energies and relatively simple spectral features, which reflect their high symmetry and stability. The adiabatic electronic binding energies of M@Au₁₂⁻ were measured to be 3.70 ± 0.03, 3.77 ± 0.03, and 3.76 ± 0.03 eV for M = V, Nb, and Ta, respectively. Comparison of density functional calculations with experimental data established the highly symmetric icosahedral structures for the 18-electron cluster anions, which may be promising building blocks for cluster-assembled nanomaterials in the form of stoichiometric [M@Au₁₂⁻]X⁺ salts.
2004. "Remarkable Second-Order Optical Nonlinearity of Nano-Sized Au₂₀ Cluster: A TDDFT Study." Chemical Physics Letters 388(4-6):353-357. Abstract The dipole polarizability, static first hyperpolarizability, and UV-vis spectrum of the recently identified nano-sized tetrahedral cluster of Au₂₀ have been investigated by using time-dependent density functional response theory. We have discovered that the Au₂₀ cluster possesses remarkably large molecular second-order optical nonlinearity with the first hyperpolarizabilty ( βxyz) calculated to be 14.3 x 10⁻³⁰ electrostatic unit (esu). The analysis of the low-energy absorption band suggests that the charge transfer from the edged gold atoms to the vertex ones plays the key role in nonlinear optical (NLO) response of Au₂₀.
2004. "Significant Interactions between Uranium and Noble-Gas Atoms: Coordination of the UO2+ Cation by Ne, Ar, Kr, and Xe Atoms." Angewandte Chemie International Edition 43(19):2554-2557. Abstract Laser-ablated uranium cation reacts with O2 to give UO2+, which is found to form UO2+(Ng)n (Ng = Ne, Ar, Kr, Xe) complexes on condensation with excess noble gas. Experiments with mixtures of noble gases lead to five new absorptions for the mixed UO2+(Ng)x(Ng')y complexes and show that the coordination number is five for Ng = Ar, Kr, and Xe. These results are consistent with predictions by relativistic density functional calculations and indicate significant bonding between U and noble-gas atoms.
2004. "On the Noble-Gas Induced Intersystem Crossing for the CUO Molecule: Experimental and Theoretical investigations of CUO(Ng)n (Ng = Ar, Kr, Xe; n = 1, 2, 3, 4) Complexes in Solid Neon." Inorganic Chemistry 43(3):882-894. Abstract Uranium atoms excited by laser ablation react with CO in excess neon to produce the novel CUO molecule, which forms distinct Ng complexes (Ng = Ar, Kr, Xe) when the heavier noble gases are added. The CUO(Ng) complexes are identified through CO isotopic and Ng substitution on the neon matrix infrared spectra and by comparison to DFT frequency calculations. The U-C and U-O stretching frequencies of CUO(Ng) complexes are slightly red shifted from frequencies for the 1S+ CUO ground state, which identifies singlet ground state CUO(Ng) complexes. In solid neon the CUO molecule is also a complex CUO(Ne)n, and the CUO(Ne)n-1(Ng) complexes are likewise specified. The next singlet CUO(Ne)x(Ng)2 complexes in excess neon follow in like manner. However, the higher CUO(Ne)x(Ng)n complex (n = 3, 4) stretching modes approach pure argon matrix CUO(Ar)n values and isotopic behavior, which are characterized as triplet ground state complexes by DFT frequency calculations. This work suggests that the singlet-triplet crossing occurs with 3 Ar, 3 Kr or 4 Xe and a balance of Ne atoms coordinated to CUO in the neon matrix host.
2004. "On The Electronic Structure of Molecular UO2 in the Presence of Ar Atoms: Evidence for Direct U-Ar Bonding." Journal of the American Chemical Society 126(11):3424-3425. Abstract Calculations via scalar-relativistic density functional theory (DFT) and ab initio CCSD(T) methodologies are used to explore the possibility of direct interactions between molecular UO2 and Ar atoms. The 3Hg electronic state of UO2, which is an excited state of the isolated molecule, exhibits significant bonding to Ar in the model complexes UO2(Ar) and UO2(Ar)5. The calculated vibrational frequencies of ground-state 3Φu UO2 and UO2(Ar)5 with an (fφ)1(fδ)1 electron configuration agree well with the observed frequencies of UO2 in solid neon and solid argon, respectively. The results strongly suggest that the ground electron configuration of UO2 changes from 5f17s1 to 5f2 when the matrix host is changed from neon to argon.
2004. "Photoelectron Spectroscopy of Free Polyoxoanions Mo6O19 2- and W6O19 2- in the Gas Phase." Journal of Physical Chemistry A 108(46):10089-10093. Abstract Two doubly charged polyoxoanions, Mo6O19 2- and W6O19 2-, were observed in the gas phase using electrospray ionization. Their electronic structures were investigated using photoelectron spectroscopy and quasi-relativistic density functional calculations. Each dianion was found to be highly stable despite the presence of strong intramolecular coulomb repulsion, estimated to be about 2 eV for each system. The valence detachment features were all shown to originate from electronic excitations involving oxygen lone-pair type orbitals. Their observed energies were in excellent agreement with the theoretical vertical detachment energies calculated using time-dependent density functional theory. Despite being multiply charged, polyoxometalate oxide clusters can be studied in the gas phase, providing the opportunity for detailed benchmark theoretical studies on the electronic structures of these important transition-metal oxide systems.
2004. "Raman Under Nitrogen. The High-Resolution Raman Spectroscopy of Crystalline Uranocene, Thorocene, and Ferrocene." Journal of Chemical Physics 120(6):2708-2718. Abstract The utility of recording Raman spectroscopy under liquid nitrogen, a technique we call Raman Under Nitrogen (RUN), is demonstrated for ferrocene, uranocene and thorocene. Using RUN, low temperature (liquid nitrogen cooled) Raman spectra for these compounds exhibit higher resolution than previous studies and new vibrational features are reported. The first Raman spectra of crystalline uranocene at 77 K are reported using excitation from argon (5145 Å) and krypton (6764 Å) ion lasers. The spectra obtained showed bands corresponding to vibrational transitions at 212, 236, 259, 379, 753, 897, 1500, and 3042 cm-1 , assigned to ring-metal-ring stretching, ring-metal tilting, out-ofplane CCC bending, in-plane CCC bending, ring-breathing, C-H bending, CC stretching and CH stretching, respectively. The assigned vibrational bands are compared to those of uranocene in THF and thorocene. All vibrational frequencies of the ligands, except the 259 cm-1 out-of-plane CCC bending mode, were found to increase upon coordination. A broad polarizable band centered about ~460 cm-1 was also observed. The 460 cm-1 band is greatly enhanced relative to the vibrational Raman transitions with excitation from the krypton ion laser, which is indicative of an electronic resonance Raman process as has been shown previously. The electronic resonance Raman band is observed to split into three distinct bands at 450, 461 and 474 cm-1 with 6764 Å excitation. Relativistic density functional theory (DFT) is used to provide theoretical interpretations of the measured spectra.
2004. "Noble Gas-Uranium Coordination and Intersystem Crossing for the CUO(Ne)x(Ng)n (Ng = Ar, Kr, Xe) Complexes in Solid Neon." New Journal of Chemistry 28(2):289-294. Abstract Atomic uranium excited by laser ablation reacts with CO in excess neon to produce the novel CUO molecule, which forms weak complexes CUO(Ne)m with neon and stronger complexes CUO(Ne)x(Ng)n (Ng = Ar, Kr, Xe) when the heavier noble gas atoms are present. The heavier CUO(Ne)m-1(Ng) complexes are identified through the effects of CO isotopic and Ng substitution on the neon matrix infrared spectra and by comparison to DFT frequency calculations on model complexes CUO(Ng) (Ng = Ne, Ar, Kr, Xe). The U-C and U-O stretching frequencies of CUO(Ne)m-1(Ng) complexes are slightly red shifted from 1047 and 872 cm-1 frequencies for the 1Sigma+ CUO ground state neon complex, which identifies singlet ground state CUO(Ne)m-1(Ng) complexes in solid neon. The next singlet CUO(Ne)x(Ng)2 complexes in excess neon follow in like manner. However, stretching modes and the isotopic shifts of the higher CUO(Ne)x(Ng)n complex approach those of the pure argon matrix CUO(Ar)n complex, which characterizes triplet ground state complexes by comparison to DFT frequency calculations.
2003. "Hydrocarbon Analogues of Boron Clusters: Planarity, Aromaticity, and Antiaromaticity." Nature Materials 2(12):827-833. Abstract An interesting feature of elemental boron and boron compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of boron is also dominated by three-dimensional cage structures. Despite its proximity to carbon, elemental boron clusters have been scarcely studied experimentally and their structures and chemical bonding have not been fully elucidated. Here we report experimental and theoretical evidence that small boron clusters prefer planar structures and exhibit aromaticity and antiaromaticity according to the Hückel rules, akin to planar hydrocarbons. Aromatic boron clusters possess more circular shapes whereas antiaromatic boron clusters are elongated, analogous to structural distortions of antiaromatic hydrocarbons. The planar boron clusters are thus the only series of molecules other than the hydrocarbons to exhibit size-dependent aromatic and antiaromatic behavior and represent a new dimension of boron chemistry. The stable aromatic boron clusters may exhibit similar chemistries as that of benzene, such as forming sandwich-type metal compounds.
2003. "Bonding of Multiple Noble-Gas Atoms to CUO in Solid Neon: CUO(Ng)(n) (Ng = Ar, Kr, Xe; n = 1, 2, 3, 4) Complexes and the Singlet-Triplet Crossover Point." Chemistry - a European Journal 9(19):4781-4788. Abstract Laser-ablated U atoms codeposited with CO in excess neon produce the novel CUO molecule, which forms distinct Ng complexes (Ng = Ar, Kr, Xe) with the heavier noble gases. The CUO(Ng) complexes are identified through CO isotopic and Ng reagent substitution and comparizon to results of DFT frequency calculations.
2003. "Au20: A Tetrahedral Cluster." Science 299(7):864-867. Abstract Photoelectron spectroscopy revealed that a 20 atom gold cluster has an extremely large energy gap, which is even greater than that of C60, and an electron affinity comparable with that of C60. This observation suggests that the Au20 cluster must be extremely stable and chemically inert. Using relativistic density functional calculations, we found that Au20 possesses a remarkable tetrahedral structure, which is a fragment of the bulk face-centered cubic lattice of gold with a small structural relaxation. Au20 is thus a true cluster molecule, while at the same time it is exactly part of the bulk, but with very different properties. The tetrahedral Au20 may possess interesting catalytic properties and may be synthesized in bulk quantity or assembled on non-interacting surfaces.
2003. "The Quantum Chemistry of d- and f-element Complexes: From an Approximate Existence to Functional Happiness." Faraday Discussions 124:1-24. Abstract This Lecture provides a survey of the development of the field of modern quantum inorganic chemistry through about 1980, which has led to its current state.
2003. "Noble Gas--Actinide Complexes of the CUO Molecule with Multiple Ar, Kr, and Xe Atoms in Noble-Gas Matrices." Journal of the American Chemical Society 125(10):3126-3139. Abstract Laser-ablated U atoms react with CO in excess argon to produce CUO, which is trapped in a triplet state in solid argon at 7 K, based on agreement between observed and relativistic density functional theory (DFT) calculated isotopic frequencies (12C16O, 13C16O, 12C18O). This observation contrasts a recent neon matrix investigation, which trapped CUO in a linear singlet state calculated to be about 1 kcal/mol lower in energy. Experiments with krypton and xenon give results analogous to those with argon. Similar work with dilute Kr and Xe in argon finds small frequency shifts in new four-band progressions for CUO in the same triplet states trapped in solid argon and provides evidence for four distinct CUO(Ar)4-n(Ng)n (Ng = Kr, Xe, n = 1, 2, 3, 4) complexes for each Ng. DFT calculations show that successively higher Ng complexes are responsible for the observed frequency progressions. This work provides the first evidence for noble gas-actinide complexes, and the first example of neutral complexes with four noble gas atoms bonded to one metal center.
2002. "Noble Gas-Actinide Compounds: Evidence for the Formation of Distinct CUO(Ar)4-n(Xe)n and CUO(Ar)4-n(Kr)n (n = 1, 2, 3, 4) Complexes ." Journal of the American Chemical Society 124(31):9016. Abstract Laser-ablated U atoms react with CO in excess argon to produce CUO, which gives rise to 852.5 and 804.3 cm-1 infrared absorptions for the triplet molecule CUO(Ar)n (n > 1) complex in solid argon at 7 K. Relativistic density functional calculations suggest that the binding energy is maximized when five argon atoms can complex to CUO. When 1-3% Xe is added to the Ar/CO mixture, strong absorptions appear at 848.0 and 801.3 cm-1 and dominate new four-band progressions, which increase on annealing to 35-50 K as Xe replaces Ar in the intimate coordination sphere. Analogous results are found for Kr in argon. This work provides evidence for distinct CUO(Ar)4-n(Ng)n (Ng = Kr, Xe; n = 1, 2, 3, 4) complexes and the first examples of neutral complexes that have four noble gas atoms bonded to one metal center.
2002. "Experimental and Theoretical Studies of the Products of Laser-Ablated Thorium Atom Reactions with H2O in Excess Argon." Journal of the American Chemical Society 124(23):6723-6733. Abstract Reactions of laser-ablated Th atoms with H2O during condensation in excess argon have formed a variety of intriguing new Th, H, O species. Infrared absorptions at 1406.0 and 842.6 cm-1 are assigned to the H-Th and ThdO stretching vibrations of HThO. Absorptions at 1397.2, 1352.4, and 822.8 cm-1 are assigned to symmetric H-Th-H, antisymmetric H-Th-H, and ThdO stretching vibrations of the major primary reaction product H2ThO. Thorium monoxide (ThO) produced in the reaction inserts into H2O to form HThO(OH), which absorbs at 1341.0, 804.0, and 542.6 cm-1. Both HThO(OH) and ThO2 add another H2O molecule to give HTh(OH)3 and OTh(OH)2, respectively. Weaker thorium hydride (ThH1-4) absorptions were also observed. Relativistic DFT and ab initio calculations were performed on all proposed molecules and other possible isomers. The good agreement between experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts provides support for these first identifications of Th, H, O molecular species.
2002. "Noble Gas-Actinide Compounds: Complexation of the CUO Molecule by Ar, Kr, and Xe Atoms in Noble Gas Matrices ." Science 295(5563):2242-2245. Abstract The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix (804.3 and 852.5 cm -1 ) than in a solid neon matrix (872.2 and 1047.3 cm -1 ). Related experiments in a matrix consisting of 1% Ar in Ne suggest that the Ar atoms are interacting directly with the CUO molecule. Relativistic density functional calculations predict that CUO can bind directly to an Ar atom (U-Ar = 3.16 angstroms; binding energy = 3.2 kcal/mol), accompanied by a change in the ground state from a singlet to a triplet. The experimental and theoretical results suggest the possibility that multiple Ar atoms can bind to a single CUO molecule.
2002. "Experimental Observation and Confirmation of Icosahedral W@Au12 and Mo@Au12 Molecules." Angewandte Chemie International Edition 41(24):4786-4789. Abstract The recently predicted W@Au12 cluster has been observed and probed experimentally using anion photoelectron spectroscopy. It is shown that this unique molecule and its Mo congener indeed possess an icosahedral structure and a large HOMO-LUMO gap. Relativistic density functional theory is used to calculate their geometries, energetics, and energy spectra. The simulated density-of-states spectra are in good agreement with the photoelectron spectra, confirming the icosahedral structure of these complexes.
2002. "Electronic Structures, (d-p)p Conjugation Effects, and Spectroscopic Properties of Polyoxometalates: M6O192- (M = Cr, Mo, W) ." Journal of Cluster Science 13(1):137-163. Abstract The electronic structures and bonding of isopoly oxometalates M6O192- (M = Cr, Mo, W) have been investigated by using ab initio and relativistic density functional methods. We have discussed the role of the central oxygen atom and the (d-p)p conjugation interactions between the metal and bridging oxygen atoms. It is found that there exist 12 three-centered two-electron (d-p-d)p bonds for the three M4(m-O)4 planar rings in M6O192- ions and these hexametalates are considered to have quasi-aromaticity. The (d-p)p conjugation effects play essential role in stabilizing these cluster compounds, and the reduced (d-p)p conjugation effects account for the instability of the isopoly oxochromate ion, Cr6O192-. The vibrational spectra and electronic spectra of M6O192- ions are evaluated and assigned theoretically and the calculated spectra are in fairly good agreement with the measured experimental results.
2001. "The Electronic Structures of Organoactinide Complexes Via Relativistic Density Functional Theory: Applications to the Actinocene Complexes An(n8-C8H8)2 (An = Th-Am)." In Computational Organometallic Chemistry, ed. Thomas R. Cundari, pp. 345-379. Marcel Dekker, Inc., New York, NY. Abstract Monograph bringing together experts in the field of computational organometallic chemistry to present a "how to" to introduce this field to experimentalists and theorists.
2000. "Ground-State Reversal by Matrix Interaction: Electronic States and Vibrational Frequencies of CUO in Solid Argon and Neon." Angewandte Chemie International Edition 39(24):4565-4567. Abstract The reactions of laser-ablated metal atoms with small molecules during their condensation in frozen noble gas matrices have led to a remarkable number of fundamental small molecules that provide new insights into the structures of and bonding in metal complexes.