Showing papers by "Lester Andrews published in 1999"
TL;DR: In this article, the upper band is largely U−C and the lower band mostly U−O in vibrational character, and it was shown that U(C2)UO2 undergoes further photochemical rearrangment to the (C2, UO)2 molecule which is characterized by symmetric and antisymmetric OUO stretching vibrations at 843.2 and 922.1 cm-1.
Abstract: Laser-ablated uranium atoms have been reacted with CO molecules during condensation with neon at 4 K. Absorptions at 1047.3 and 872.2 cm-1 are assigned to the CUO molecule formed from the insertion reaction that requires activation energy. Isotopic substitution shows that the upper band is largely U−C and the lower band mostly U−O in vibrational character. Absorptions at 2051.5, 1361.8, and 841.0 cm-1 are assigned to the OUCCO molecule, which is formed by the CO addition reaction to CUO and ultraviolet−visible photon-induced rearrangment of the U(CO)2 molecule. The OUCCO molecule undergoes further photochemical rearrangment to the (C2)UO2 molecule, which is characterized by symmetric and antisymmetric OUO stretching vibrations at 843.2 and 922.1 cm-1. The uranium carbonyls U(CO)x (x = 1−6) are produced on deposition or on annealing. Evidence is also presented for the CUO- anion and U(CO)x- (x = 1−5) anions, which are formed by electron capture. Relativistic density functional theoretical calculations have...
108 citations
TL;DR: In this article, laser ablation of transition metal targets with concurrent 11 to 12 K condensation of CO2-Ar mixtures produces a sharp metal independent infrared absorption at 1657.0 cm−1 due to CO2−, which is formed from the capture of ablated electrons by CO2 molecules during the condensation process.
Abstract: Laser ablation of transition metal targets with concurrent 11 to 12 K condensation of CO2–Ar mixtures produces a sharp metal independent infrared absorption at 1657.0 cm−1 due to CO2−, which is formed from the capture of ablated electrons by CO2 molecules during the condensation process. Two additional metal independent absorptions are produced at 1856.7 and 1184.7 cm−1 on matrix annealing to 25 K to allow diffusion and reaction of CO2 and CO2−. Isotopic substitution (13CO2, C18O2, C16,18O2, and mixtures) shows that these two vibrations involve two equivalent CO2 subunits. The excellent agreement with frequencies, intensities, and isotopic frequency ratios from density-functional calculations supports assignment to the symmetrical C2O4− anion with D2d symmetry. Photodissociation (470–580 nm) and failure to observe these absorptions in identical experiments doped with the electron trapping molecule CCl4 further support the molecular anion assignments. Although absorptions were observed for weak (CO2)(CO2−)...
79 citations
TL;DR: The title cation and molecules have been prepared by reactions of laser-ablated metal cations and atoms with NO during condensation in excess neon at 4 K, and the isolated NUO+ cation observed here provides a vibrational model for its important isoelectronic UO22+ analog, which has only been characterized in condensed phases where partial neutralization of the dication readily occurs as mentioned in this paper.
Abstract: The title cation and molecules have been prepared by reactions of laser-ablated metal cations and atoms with NO during condensation in excess neon at 4 K. Infrared fundamentals for the NUO and NThO molecules blue shift 1.6%–2.9% on going from argon to neon matrices and are calculated from 5.8% to 0.0% too high using density functional theory, GAUSSIAN 98, and pseudopotentials on the actinide metal. The isolated NUO+ cation, formed in previous gas-phase ion–molecule reactions, is characterized by new 1118.6 and 969.8 cm−1 neon matrix absorptions. Two normal modes (isotopic frequencies) are accurately modeled by the calculations for NUO+, NUO, and NThO. The isolated NUO+ cation observed here provides a vibrational model for its important isoelectronic UO22+ analog, which has only been characterized in condensed phases where partial neutralization of the dication readily occurs.
78 citations
TL;DR: In this paper, the first spectroscopic characterization of Rh and Ir carbonyl cations and anions except for the stable tetracarbonyl anions in solution was provided.
Abstract: Laser ablation produces metal atoms, cations, and electrons for reaction with CO during condensation in excess neon at 4 K. Infrared spectra are observed for the metal carbonyls, cations, and anions, which are identified from isotopic shifts (13CO, C18O) and splittings using mixed isotopic precursors. Density functional calculations with pseudopotentials for Rh and Ir predict the observed carbonyl stretching frequencies within 1−2%. This characterization of the simple RhCO+, RhCO, and RhCO- (and Ir) species over a 350 cm-1 range provides a scale for comparison of larger catalytically active Rh and Ir carbonyl complexes in solution and on surfaces to estimate charge on the metal center. This work provides the first spectroscopic characterization of Rh and Ir carbonyl cations and anions except for the stable tetracarbonyl anions in solution.
75 citations
TL;DR: In this article, the vibrational spectra of the linear Cu(CO)1−4+ and tetrahedral Cu( CO)4+ cations were analyzed in solid neon and argon matrices.
Abstract: Laser-ablated copper atoms, cations, and electrons react with CO molecules to give binary copper carbony neutral complexes as well as cation and anion complexes, which are isolated in solid neon and argon matrices. Based on isotopic substitution as well as density functional calculations of isotopic frequencies, absorptions at 2234.4, 2230.4, 2211.3, and 2202.1 cm−1 in neon are assigned to C–O stretching vibrations of the linear CuCO+ and Cu(CO)2+, trigonal planar Cu(CO)3+, and tetrahedral Cu(CO)4+ cations. The absorptions at 1746.2, 1793.9, and 1838.9 cm−1 in neon and at 1733.4, 1780.8, and 1829.7 cm−1 in argon are assigned to the linear CuCO− and Cu(CO)2−, and trigonal planar Cu(CO)3− anions, respectively. The solid neon observations of Cu(CO)1–3 are 20–9 cm−1 blue shifted from the argon matrix counterparts, which are in agreement with previous thermal copper atom matrix isolation studies. This work provides the first vibrational spectra of Cu(CO)1–4+ and Cu(CO)1–3−.
68 citations
TL;DR: Tanaka et al. as mentioned in this paper showed that the FeCO molecule has the same 3Σ− ground state in solid neon that has been observed at 46.5 cm−1 in a recent high resolution gas phase investigation.
Abstract: Laser-ablated iron atoms, cations, and electrons have been reacted with CO molecules during condensation in excess neon. The FeCO molecule is observed at 1933.7 cm−1 in solid neon. Based on isotopic shifts and density functional calculations, the FeCO molecule has the same 3Σ− ground state in solid neon that has been observed at 1946.5 cm−1 in a recent high resolution gas phase investigation [Tanaka et al., J. Chem. Phys. 106, 2118 (1997)]. The C–O stretching vibration of the Fe(CO)2 molecule is observed at 1917.1 cm−1 in solid neon, which is in excellent agreement with the 1928.2 cm−1 gas phase value for the linear molecule. Anions and cations are also produced and trapped, absorptions at 1782.0, 1732.9, 1794.5, and 1859.7 cm−1 are assigned to the linear FeCO−, Fe(CO)2−, trigonal planar Fe(CO)3−, and C3v Fe(CO)4− anions, respectively, and 2123.0, 2134.0 cm−1 absorptions to the linear FeCO+ and Fe(CO)2+ cations. Doping these experiments with CCl4 virtually eliminates the anion absorptions and markedly inc...
66 citations
TL;DR: The second segment of an investigation into the reaction products of laser-ablated lanthanide metal atoms with O2 was reported in this article, where it was found that the average vibrational frequencies of the early lanthanides dioxide anions are lower than their neutral counterparts, while those of the late lanthanIDE dioxide anion are higher.
Abstract: This paper is the second segment of an investigation into the reaction products of laser-ablated lanthanide metal atoms with O2. There is general agreement with previous gas-phase and matrix infrared observations of neutral lanthanide monoxides; the frequencies of monoxide cations and anions are original to this work. The dioxide anion vibrational frequencies of all late lanthanides and neutral frequencies of five of the last seven are reported. In conjunction with the earlier part of this study, it is found that the average vibrational frequencies of the early lanthanide dioxide anions are lower than their neutral counterparts, while those of the late lanthanide dioxide anions are higher. Doping the electron scavenger, CCl4, into these samples provides a diagnostic test for the identification of molecular cations and anions by matrix infrared spectroscopy.
64 citations
TL;DR: In this paper, the late transition metal atoms Cr through Ni react with CO2 molecules to give the insertion products OMCO, which have been isolated in solid argon, and the excellent agreement between the observed frequencies and isotopic frequency ratios with those calculated by density functional theory supports these assignments.
Abstract: Laser-ablated late transition metal atoms Cr through Ni react with CO2 molecules to give the insertion products OMCO, which have been isolated in solid argon. The insertion OMCO- molecular anions (Cr through Cu) were formed by electron capture and/or reaction with CO2-, and the addition MCO2- anions (M = Co, Ni, Cu) were produced by direct reaction with CO2-. The excellent agreement between the observed frequencies and isotopic frequency ratios with those calculated by density functional theory supports these assignments.
57 citations
TL;DR: In this paper, the MO2− anions, formed via capture of ablated electrons by the neutral molecules, were identified from isotopic splittings on their matrix infrared spectra and from density functional theory calculations of isotopic frequencies.
Abstract: Laser-ablated chromium, molybdenum, and tungsten atoms react with O2 in excess neon during condensation to form the MO2 dioxide molecules as major products In addition, the MO2− anions, formed via capture of ablated electrons by the neutral molecules, were identified from isotopic splittings on their matrix infrared spectra and from density functional theory (DFT) calculations of isotopic frequencies Evidence is also presented for CrO3 and the CrO3− anion Doping with CCl4 to serve as an electron trap gave the same neutral molecules and virtually eliminated the anion absorptions, which strongly supports the anion identification
56 citations
TL;DR: In this article, isolated rhodium carbonyls were identified by isotopic substitution (13CO, C18O, and mixtures), electron trapping with added CCl4, and comparison with DFT calculations of isotopic frequencies.
Abstract: Laser-ablated Rh+, Rh, and electrons react with CO on condensation in excess neon at 4 K to form RhCO+, RhCO, RhCO-, and Rh(CO)2+, Rh(CO)2, Rh(CO)2-, and higher carbonyls. These rhodium carbonyls are identified by isotopic substitution (13CO, C18O, and mixtures), electron trapping with added CCl4, and comparison with DFT calculations of isotopic frequencies. This is the first spectroscopy of isolated rhodium carbonyl cations and anions. The isolated monocarbonyl species provide a scale to estimate local charge on Rh(CO) sites in catalyst systems.
55 citations
TL;DR: In this paper, the products of the reaction of Sc and dioxygen have been reinvestigated, and the previously observed band at 722.5 cm(-1) is assigned as the b(2) mode of ScO2-.
Abstract: The products of the reaction of Sc and dioxygen have been reinvestigated. By adding the electron-trapping molecule CCl4 additional information about the IR spectra has been obtained, as well as the observation of new bands. New ab initio calculations are also performed on possible products of the Sc plus O-2 reaction. The previously observed band at 722.5 cm(-1) is assigned as the b(2) mode of ScO2-. Bands arising from ScO+, Sc(O-2)(+), and(O-2)ScO are also assigned. We are still unable to assign any bands to OScO. The problems associated with the computational study of ScO2 are discussed.
TL;DR: In this article, photoisomerization of OMCO molecules to form the side-bonded OM−(η2-CO) isomers and photoionization to give the OMCO+ and OMOC+ cations proceed upon mercury arc photolysis.
Abstract: Laser-ablated V and Ti atoms react with CO2 molecules to give primarily the insertion products, OMCO and O2M(CO)2, which have been isolated in a solid argon matrix. Photoisomerization of OMCO molecules to form the side-bonded OM−(η2-CO) isomers and photoionization to give the OMCO+ and OMOC+ cations proceed upon mercury arc photolysis. The product absorptions were identified by isotopic substitution and density functional calculations of isotopic frequencies.
TL;DR: In this paper, the first thorium carbonyl complex, ThCO, which rearranges to CThO, was described, which is a relatively new area of research, in part because of the experimental challenges faced in handling and characterizing actinide complexes.
Abstract: Transition metal carbonyl complexes, M(CO){sub n}, are cornerstones of modern coordination chemistry and organometallic chemistry. Carbon monoxide activation and reduction by transition metal atoms are important in a great many industrial processes. By contrast, the coordination chemistry of CO with the actinide elements is a relatively new area of research, in part because of the experimental challenges faced in handling and characterizing actinide complexes. The authors report a study of reactions of laser-ablated thorium atoms with carbon monoxide in excess neon. These experiments form the first thorium carbonyl complex, ThCO, which rearranges to CThO. Although this chemistry seems to parallel to that of CO with uranium atoms, it is distinctly different because of the intrinsic differences between Th and U.
TL;DR: In this article, the vibrational frequencies of the OYO and OLaO molecules were analyzed and their symmetric stretching modes were found to be unusually intense and weakly bound.
Abstract: Laser-ablated Y and La condensed with O2 in excess argon formed small metal oxides, cations, and anions, which were identified from isotopic substitution and density functional frequency calculations. In accord with gas phase thermochemistry, the OYO and OLaO molecules are more weakly bound than YO and LaO, on the basis of vibrational frequencies, and their symmetric stretching modes are unusually intense. The bent OYO- and OLaO- anions, the cyclic Y(O2)+ and La(O2)+, and linear OLaO+ cation isomers are characterized. The (O2)MO and MO3 isomers are also observed.
TL;DR: In this article, laser ablation atoms were reacted with dioxygen diluted in argon during condensation at 10 K. Density functional theory (B3LYP) calculations were performed on product molecules, which were identified on the basis of isotopic frequency shifts and correlation with density functional calculations.
Abstract: Platinum and palladium atoms produced by laser ablation were reacted with dioxygen diluted in argon during condensation at 10 K. Reaction products, including the M(O2) and (O2)M(O2) complexes prepared with thermal metal atoms, and the platinum oxides PtO, OPtO, PtO3, OOPtO, and (O2)PtO, were analyzed by matrix infrared spectroscopy. Absorptions due to PdO and OPdO were not identified. Density functional theory (B3LYP) calculations were performed on product molecules, which were identified on the basis of isotopic frequency shifts and correlation with density functional calculations. The most interesting new molecule produced here, linear OPtO, can also be produced by photolysis of the cyclic Pt(O2) complex.
TL;DR: Based on density functional theory calculations of structures and vibrational frequencies, the 2130.8 and 1274.4 cm−1 bands were assigned to the C2O4+ cation with C2h symmetry, and the 1852.4, 1189.2, and 679.2 cm− 1 bands were allocated to the (CO2−)(CO2)x(x=1,2) anion complexes.
Abstract: Laser ablation of transition metal targets with concurrent 4 K codeposition of CO2/Ne mixtures produces metal independent infrared absorptions at 1658.2 and 1421.6 cm−1 due to CO2− and CO2+. Additional metal independent absorptions at 2130.8 and 1274.4 cm−1, and at 1852.4, 1189.2, and 679.2 cm−1 increase on annealing to 8 K. Isotopic substitution shows that both band sets involve two equivalent CO2 subunits. Based on density functional theory calculations of structures and vibrational frequencies, the 2130.8 and 1274.4 cm−1 bands are assigned to the C2O4+ cation with C2h symmetry, and the 1852.4, 1189.2, and 679.2 cm−1 bands are assigned to the C2O4− anion with D2d symmetry. Evidence is also obtained for (CO2−)(CO2)x(x=1,2) anion complexes.
TL;DR: In this paper, laser-ablated vanadium and titanium atoms were reacted with CO molecules during condensation in excess neon, and the V(CO)x and Ti(COx)x (x = 1−6) molecules were formed during deposition or on annealing and photolysis.
Abstract: Laser-ablated vanadium and titanium atoms were reacted with CO molecules during condensation in excess neon. The V(CO)x and Ti(CO)x (x = 1−6) molecules are formed during deposition or on annealing and photolysis. The V(CO)x-, Ti(CO)x- (x = 1−6) anions and TiCO+ cation are also produced and identified on the basis of isotopic substitution and density functional calculations. Selective photolysis and CCl4 doping experiments strongly support the identification of the anions and cation.
TL;DR: In this article, the authors used isotopic substitution as well as density functional calculations to identify the stretching vibrations of the ScCO molecule in solid argon and/or neon matrices.
Abstract: Laser-ablated Sc atoms and ions react with CO molecules to give primarily the ScCO, ScCO-, and ScCO+ products, which have been isolated in solid argon and/or neon matrices. Based on isotopic substitution as well as density functional calculations, absorptions at 1834.2 cm-1 in argon and 1851.4 cm-1 in neon are assigned to C−O stretching vibrations of the ScCO molecule, 1923.5 cm-1 in argon and 1962.4 cm-1 in neon to the ScCO+ cation, and 1732.0 cm-1 in neon to the ScCO- anion, respectively. Higher carbonyls Sc(CO)2,3,4 and Sc(CO)+2,3 are also produced on annealing. Similar argon matrix experiments with Y give YCO and YCO+.
TL;DR: In this article, laser-ablation of over ten different transition, lanthanide, and actinide metals with concurrent codeposition of acetylene/argon samples at 7 K produced metal independent absorptions for CCH, CCH−, C4H, and c4H2, in agreement with previous matrix isolation work.
Abstract: Laser-ablation of over ten different transition, lanthanide, and actinide metals with concurrent codeposition of acetylene/argon samples at 7 K produced metal independent absorptions for CCH, CCH−, C4H, and C4H2, in agreement with previous matrix isolation work, and a sharp new 1820.4 cm−1 band. Isotopic substitution showed this band to be due to a largely C–C stretching mode of a species with one H and two inequivalent carbon atoms. The same species were observed in solid neon samples at 4 K, and the neon matrix counterpart of the new band was found at 1832.2 cm−1. When CO2 was added to serve as an electron trap, the yield of CCH− at 1772.8 cm−1 decreased and the 1832.2 cm−1 band increased relative to CCH at 1837.9, 1835.0 cm−1. Quantum chemical calculations at the coupled-cluster and density functional levels predict the C–C stretching mode of CCH+ between this mode for CCH and CCH− and support assignment of this new infrared absorption to the CCH+ cation in solid argon and neon.
TL;DR: In this article, the laser-ablated rh atoms react to give RhO, the linear dioxide ORhO, side-bound dioxygen adduct (O2)RhO2, and several ORh O(O 2 ) complexes.
Abstract: Laser-ablated Rh atoms react to give RhO, the linear dioxide ORhO, the side-bound dioxygen adduct (O2)RhO2, and several ORhO(O2) complexes. In addition, a large number of Rhx(O2)y complexes are obs...
TL;DR: In this article, the authors characterized cyclic-O6+ and trans O6+ species in solid argon and neon using electron impact, Townsend discharge, and laser-ablation methods.
Abstract: Charged transient species in the oxygen system have been trapped in solid argon and neon using electron impact, Townsend discharge, and laser-ablation methods. The previously identified O3−, O4−, and O4+ species are observed in these experiments. Absorptions at 1435.0 and 1429.5 cm−1 in solid neon are characterized as cyclic-O6+ and trans-O6+, respectively, on the basis of annealing behavior, isotopic substitution, multiplet structure in mixed 16O2+18O2 experiments, and density functional calculations. Cyclic-O6+ is observed at 1416.1 cm−1 in solid argon, a smaller displacement than found for cyclic-O4+ in solid argon.
TL;DR: In this article, the reaction of laser-ablated Ti, Zr, and Hf atoms with N2 in excess argon and excess dinitrogen have produced the MN and (N2)xMN molecules.
Abstract: Reactions of laser-ablated Ti, Zr, and Hf atoms with N2 in excess argon and excess dinitrogen have produced the MN and (N2)xMN molecules in addition to M(μ–N)2M with no dinitrogen bond. Evidence is presented for simple η1–N2 and higher complexes for each metal. The observation of cyclic Ti(N2) and Zr(N2) molecules with N–N stretching frequencies at 1125.9 and 1022.8 cm−1, respectively, indicate significant activation of the dinitrogen bond. The identification of product molecules is based on isotopic substitution and the results of density functional theory frequency calculations.
TL;DR: In this article, density functional calculations predict these frequencies within 1% and the isotopic shifts for different C−O stretching modes within averages of 1 to 2 cm-1 including vibrational modes for both C3v and D2d tetracarbonyl anion structures.
Abstract: Laser-ablated ruthenium and osmium atoms, cations and electrons have been reacted with CO molecules during condensation in excess neon. The Ru(CO)x and Os(CO)x (x = 1−5) molecules are formed during sample deposition or on annealing. The Ru(CO)x- and Os(CO)x- (x = 1−4) anions are formed by electron capture, and the RuCO+ and OsCO+ cations are produced by metal cation reactions and identified from 13CO and C18O isotopic substitution, density functional calculations, and behavior on doping with CCl4 to serve as an electron trap. Density functional calculations predict these frequencies within 1% and the isotopic shifts for different C−O stretching modes within averages of 1 to 2 cm-1 including vibrational modes for both C3v and D2d tetracarbonyl anion structures.
TL;DR: In this paper, the side-ablated Sc and Ti atoms have been reacted with NO during condensation in excess argon. Matrix infrared spectra show that the major products are the side bonded Sc[NO] species and the inserted NScO and NTiO molecules based on isotopic substitution (15NI6O and 15N18O) and DIFT calculations of isotopic frequencies, which provide a match for two modes in three isotopic modifications for each molecule.
Abstract: Laser-ablated Sc and Ti atoms have been reacted with NO during condensation in excess argon. Matrix infrared spectra show that the major products are the side bonded Sc[NO] species and the inserted NScO and NTiO molecules based on isotopic substitution (15NI6O and 15N18O) and DIFT calculations of isotopic frequencies, which provide a match for two modes in three isotopic modifications for each molecule. The NScO and NTiO molecules are nitride/oxides with M-O stretching modes only 46-88/cm below the diatomic metal oxides but M-N stretching modes 314-442/cm lower than the diatomic metal nitride molecules. The ScN, ScO, TiN, and TiO molecules are observed as decomposition products. Evidence is also presented for the nitrosyls ScNO and TiNO, the Sc[NO]+ cation, and the NTiO- anion.
TL;DR: In this paper, the major new molecule observed here is gold dioxide, and extensive DFT calculations are compared for several silver and gold-dioxygen complexes, including gold dioxide and gold dioxide.
Abstract: The major new molecule observed here is gold dioxide. Extensive DFT calculations are compared for several silver and gold–dioxygen complexes.
TL;DR: In this article, the (ν 1 + ν 3) combination bands for the linear dioxide OIrO and the side-bound dioxygen adduct (O2)IrO2 were observed.
Abstract: Laser-ablated iridium atoms react with O2 to give the linear dioxide OIrO and the side-bound dioxygen adduct (O2)IrO2 as primary reaction products, with ν3 absorptions at 930.0 and 875.0 cm-1, respectively. The (ν1 + ν3) combination bands for these species were observed, confirming the assignments of the ν1 and ν3 modes for (O2)IrO2 and providing an estimate for the ν1 mode in OIrO. The symmetric and antisymmetric stretching modes of the Ir(O2) ring in (O2)IrO2 were also observed. Density functional calculations support these assignments and show that the (O2)IrO2 species is best formulated as a peroxide with iridium in the +6 oxidation state, providing the first example of an iridium(VI) oxo complex.
TL;DR: In this article, laser-ablation of six different metal targets with concurrent deposition of neon/nitric oxide samples at 4 K produces metal independent absorptions that can be assigned to charged (NO)2 species.
Abstract: Laser-ablation of six different metal targets with concurrent deposition of neon/nitric oxide samples at 4 K produces metal independent absorptions that can be assigned to charged (NO)2 species. The sharp 1227.3 cm−1 band and weaker 1225.1 cm−1 absorption show the different isotopic frequency ratios observed for the argon matrix counterparts at 1221.0 and 1222.7 cm−1 for trans-(NO)2− and cis-(NO)2−, respectively. Strong 1619.0 and weaker 1424.1 cm−1 absorptions, also observed in previous experiments with discharged neon, are enhanced with CCl4 doping while the (NO)2− bands are diminished, which supports cation identifications. These cation bands reverse absorbance with yellow and near-infrared photolysis. We suggested that the 1619.0 cm−1 band corresponds to the (NO)2+ isomer made by direct photoionization of cis-(NO)2. The 1424.1 cm−1 absorption shares the extreme red photosensitivity found for thermal (NO)2+ ions. Accordingly, the 1424.1 cm−1 absorption is probably due to the trans isomer, more stable i...
TL;DR: In this article, the Nb(CO)x and Ta(COx)x (x = 1−6) carbonyls formed during sample deposition or on annealing are the major products.
Abstract: Laser ablated niobium and tantalum atoms have been reacted with CO molecules during condensation in excess neon. The Nb(CO)x and Ta(CO)x (x = 1−6) carbonyls formed during sample deposition or on annealing are the major products. The novel CNbO carbide−oxide molecule was produced on visible photolysis via isomerization of the NbCO carbonyl. The ONbCCO and OTaCCO molecules were formed by near-UV−vis photon-induced rearrangement of the Nb(CO)2 and Ta(CO)2 dicarbonyls and further rearrange to the (C2)NbO2 and (C2)TaO2 molecules on UV photolysis. Evidence is also presented for the CNbO-, CTaO-, Nb(CO)x-, and Ta(CO)x- anions. The product absorptions were identified by isotopic substitution (13C16O, 12C18O, and mixtures), electron trapping with added CCl4, and density functional calculations of isotopic frequencies.
TL;DR: In this paper, vanadium atoms have been reacted with NO molecules during condensation in excess argon, and bands at 1614.5 and 1736.8 cm-1 are assigned to antisymmetric and symmetric N−O vibrations of the C2v dinitrosyl V(NO)2.
Abstract: Laser-ablated vanadium atoms have been reacted with NO molecules during condensation in excess argon. Absorptions due to NVO (998.1, 906.4 cm-1), V−η1-NO (1606.0 cm-1), V−η2-NO (1075.7 cm-1) and V−(η2-NO)2 (1119.6,1153.8 cm-1) are observed and identified via isotopic substitution and DFT calculations. Higher nitrosyls are also formed on annealing. On the basis of the observed isotopic splitting, bands at 1614.5 and 1736.8 cm-1 are assigned to antisymmetric and symmetric N−O vibrations of the C2v dinitrosyl V(NO)2, and 1715.1 and 1850.6 cm-1 bands are assigned to the analogous vibrations of V(NO)3 with C3v symmetry. The observation of (VO), (N2O) and (N2), (VO2) complexes suggests that V atoms also react with (NO)2 in these experiments.
TL;DR: In this article, the NMoO and NWO molecules are identified from isotopic substitution (nMo, 15N, 18O) and density functional theory (DFT) calculations.
Abstract: Laser-ablated Mo and W atoms react with NO to give primarily the nitride−oxide insertion products NMoO and NWO, but weak MoN and WN absorptions are also observed. The NMoO and NWO molecules are identified from isotopic substitution (nMo, 15N, 18O) and density functional theory (DFT) calculations. The M−N and M−O stretching frequencies of the 2A‘ state NMoO and NWO molecules are predicted by DFT (scale factors 0.936 ± 0.004 and 0.966 ± 0.005, respectively), but more importantly, the isotopic shifts (and normal modes) are well-described by DFT isotopic frequencies. The higher energy MoNO isomer is observed, but WNO and the M-η2-NO complexes are not found. The M-(η1-NO)x (x = 2, 3, 4) complexes are observed: mixed isotopic splittings indicate that Mo(NO)4 is tetrahedral, like Cr(NO)4, but the spectra show that W(NO)4 is distorted to C2v symmetry. In addition, a weak 3643.5 cm-1 combination band and strong 1589.3 cm-1 fundamental for (NO)2+ and the strong fundamentals for cis- and trans-(NO)2- were observed.