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Full-Text Articles in Physical Sciences and Mathematics
Matrix-Infrared Spectra Of Structural Isomers Of The Phosphorus Oxysulfide P4s3o, Zofia Mielke, Lester Andrews, Kiet A. Nguyen, Mark S. Gordon
Matrix-Infrared Spectra Of Structural Isomers Of The Phosphorus Oxysulfide P4s3o, Zofia Mielke, Lester Andrews, Kiet A. Nguyen, Mark S. Gordon
Mark S. Gordon
Photolysis of the P 4S3--03 molecular complex in solid argon with red light produced two sets of new infrared absorptions including terminal PO and symmetric P-S-P stretching modes, which are assigned to structural isomers of P4S30 with terminal oxygen at the apex and base phosphorus positions of P4S3. Further ultraviolet photolysis produced evidence for oxo-bridged P4S30 and a secondary product, P4S30 2.
Structure And Stability Of Hexacoordinated Sila Dianions, Mark S. Gordon, Marshall T. Carroll, Larry P. Davis, Larry W. Burggraf
Structure And Stability Of Hexacoordinated Sila Dianions, Mark S. Gordon, Marshall T. Carroll, Larry P. Davis, Larry W. Burggraf
Mark S. Gordon
The structures and stabilities of hexacoordinated silicon-containing dianions SiX6 2- have been investigated by using both ab initio (X= H, F) and semiempirical AMI (X= H, F, OH, Me, Cl) calculations. Both methods predict the hexacoordinated structures to be minima on the potential energy surfaces, although the semiempirical barriers for the reactions SiX6 2- -+ Six5- + x- appear to be rather overestimated based on the ab initio results for X = H, F. The positive charge on the central silicon atom actually increases as the number of ligands increases, and the role of d orbitals on that atom appears …
Theoretical Study Of Pseudorotation Of Pentacoordinated Silicon Anions: The Prototypical Sih5-, Mark S. Gordon, Theresa L. Windus, Larry W. Burggraf, Larry P. Davis
Theoretical Study Of Pseudorotation Of Pentacoordinated Silicon Anions: The Prototypical Sih5-, Mark S. Gordon, Theresa L. Windus, Larry W. Burggraf, Larry P. Davis
Mark S. Gordon
Ab initio and semiempirical calculations are used to analyze the minimum energy path for the pseudorotation of SiH5-. Both AMI and MP2/6-31++G(d,p) predict pseudorotation barriers of 2.4 kcal/mol. A decomposition of the projected vibrational frequencies along the path is used to assist in the interpretation of the process.
Predicted Enthalpies Of Formation For Silaethylene, Disilene, And Their Silylene Isomers, Jerry A. Boatz, Mark S. Gordon
Predicted Enthalpies Of Formation For Silaethylene, Disilene, And Their Silylene Isomers, Jerry A. Boatz, Mark S. Gordon
Mark S. Gordon
Enthalpies of formation of silaethylene (SiH2=CH2), methylsilylene (HSiCH3), disilene (SiH2=SiH2), and silylsilylene (HSiSiH3) are predicted by using the recently developed GAUSSIAN-! method for computing accurate molecular energies. The predicted enthalpies of formation of the silylenes are compared with enthalpies of formation determined from isodesmic reactions. Very good agreement is found between these two methods and improved values for the enthalpies of formation of silaethylene and disilene are suggested.
Theoretical Studies Of The Metallacyclopropenes C-[Mx2c2h2] (M = C, Sl, Ge, Sn; X = H, F), Jerry A. Boatz, Mark S. Gordon, Lawrence R. Sita
Theoretical Studies Of The Metallacyclopropenes C-[Mx2c2h2] (M = C, Sl, Ge, Sn; X = H, F), Jerry A. Boatz, Mark S. Gordon, Lawrence R. Sita
Mark S. Gordon
The geometries of the metallacyclopropenes c-[MX 2C2H2] (M = C, Si, Ge, Sn; X= H, F) are predicted by using the 3-21G(d) basis set and SCF wave functions. The nature of the ring bonding is investigated via analysis of the total electron density and is found to have little or no 11'-complex character. As a further probe of the electronic structure, bent bond lengths and intrinsic vibrational frequencies are computed. The classical barrier heights and the thermodynamics of the reaction MX 2 + HC==CH-- c-[MX 2C2H2] are predicted by using MP2/3-21G(d) energies.
Thermal Decomposition Processes For Sllanol, Mark S. Gordon, Lisa A. Pederson
Thermal Decomposition Processes For Sllanol, Mark S. Gordon, Lisa A. Pederson
Mark S. Gordon
Six alternative decomposition modes of silanol are examined with ab initio electronic structure theory. Geometries determined at the MP2/6-31 G( d,p) level of computation and single-point energetics obtained with MP4/MC-311 G{d,p) wave functions predict that the I, 1- and I ,2-eliminations of molecular hydrogen are both thermodynamically and kinetically competitive, with all other processes requiring at least 10 kcaljmol more energy to occur. At the highest level of theory, silanone is predicted to be 2.7 kcaljmollower in energy than hydroxysilylene.
Predicted Enthalpies Of Formation For Methyl-Substituted Disilanes, Jerry A. Boatz, Mark S. Gordon
Predicted Enthalpies Of Formation For Methyl-Substituted Disilanes, Jerry A. Boatz, Mark S. Gordon
Mark S. Gordon
Entha1pies of formation of the entire series of methyl-substituted disilanes, Si2(CH3)kH6_k (k = 1-6), are predicted by using homodesmic reactions at the MP2/6-31G(d)/ /RHF /3-21G* level of theory. The calculated values are systematically higher than the values suggested by Walsh but are in excellent agreement with the kinetic data of O'Neal, Ring, and co-workers.
Calculated Oscillator Strengths Between Vibrational Levels Of The Rotational And Trans-Bending Modes In The Ground And Lowest Excited States Of Disilene, Shiro Koseki, Mark S. Gordon
Calculated Oscillator Strengths Between Vibrational Levels Of The Rotational And Trans-Bending Modes In The Ground And Lowest Excited States Of Disilene, Shiro Koseki, Mark S. Gordon
Mark S. Gordon
Starting from the D2h structures of disilene and ethylene, the potential energy surfaces of the ground and excited singlet ( π → π) states along the rotational coordinate (au) and the trans-bending coordinate (b28) and the transition moments between these two states are calculated by using the multiconfigurational self-consistent-field (MCSCF) method with the 3-21G(d) basis set. Based on these results, the vibrational wave functions of these two states are expanded in Fourier series, and the Franck-Condon factors and the oscillator strengths are calculated between the vibrational levels of these two states. Though the transition moments are not constants along these …