Comparative studies of Mo-Mo and W-W quadruple bonds by SCF-X. cap alpha. -SW calculations and photoelectron spectroscopy

Journal Article · Wed Feb 10 04:00:00 EST 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00367a008· OSTI ID:5041516

Cotton, F A ^[1]; Hubbard, J L; Lichtenberger, D L; Shim, I

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1. Texas A and M Univ., College Station

The homologous compounds M/sub 2/Cl/sub 4/(PR/sub 3/)/sub 4/, with M = Mo and W, have been used in a combined theoretical and experimental study to compare the electronic structures of quadruple bonds between molybdenum atoms and between tungsten atoms. The theoretical work was carried out by the SCF-X..cap alpha..-SW method on the model systems with R = H, but using in all other respects the experimentally measured bond lengths and angles for the compounds with R = CH/sub 3/. Relativistic corrections were made for both the molybdenum and tungsten compounds, but were found to be significant only for the tungsten compound. The PMe/sub 3/ compounds were used for measurements, made with both He I and He II excitation, of the photoelectron spectra in the gas phase. For both compounds the highest filled orbital is the M-M delta-bonding orbital and the measured ionization energies are 6.44 and 5.81 eV for the Mo and W compounds, respectively. For both compounds the next observed ionizations, at 7.70 eV (Mo) and 7.05, 7.45 eV (W), can be assigned on experimental criteria to the M-M ..pi..-bonding orbitals. The spin-orbit splitting of the W-W ..pi.. peak shows features attributable to mixing of sigma, ..pi.., and delta components by the spin-orbit coupling operator. These peaks are followed by ionizations assignable to M-P bonding electrons at 8.41 eV (Mo) and 8.36 eV (W). The calculations predict this order correctly for the W compound but reverse the Mo-Mo ..pi.. and Mo-P ionization energies. The W-W bonding appears to be weaker than the Mo-Mo bonding, and in general the results of this study are consistent with the greater reactivity (i.e., lower chemical stability) of the W-W quadruple bond as compared to the Mo-Mo quadruple bond. 15 figures, 5 tables.

• OSTI ID: 5041516
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 104:3; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400104 -- Spectral Procedures-- (-1987)
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
ANGULAR DISTRIBUTION
BOND ANGLE
BOND LENGTHS
CHLORIDES
CHLORINE COMPOUNDS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DATA
DIMENSIONS
DISTRIBUTION
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
EXPERIMENTAL DATA
FLUIDS
GASES
HALIDES
HALOGEN COMPOUNDS
HELIUM
HIGH TEMPERATURE
HYDRIDES
HYDROGEN COMPOUNDS
INERT ATMOSPHERE
INFORMATION
IONIZATION POTENTIAL
LENGTH
LIE GROUPS
MATHEMATICAL MODELS
MATHEMATICS
MOLECULAR STRUCTURE
MOLYBDENUM COMPOUNDS
NONMETALS
NUMERICAL ANALYSIS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOSPHORUS HYDRIDES
PHOTOELECTRON SPECTROSCOPY
RARE GASES
SELF-CONSISTENT FIELD
SIMULATION
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SW GROUPS
SYMMETRY GROUPS
TEMPERATURE DEPENDENCE
THEORETICAL DATA
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS