Spectroscopy and structure of quadruply bonded complexes under extreme pressure (Re sub 2 X sub 8 sup 2 minus , Mo sub 2 Cl sub 4 (PMe sub 3 ) sub 4 )
- Los Alamos National Lab., NM (USA) Univ. of Pittsburgh, PA (USA)
Application of pressure (up to 150 kbar, where 1 kbar = 986.9 atm = 0.1 GPa) to solutions of Re{sub 2}X{sub 8}{sup 2{minus}} (X = F, Cl, Br) and Mo{sub 2}Cl{sub 4}(PMe{sub 3}){sub 4} results in smooth, continuous changes in experimental observables related to metal-metal bond length and, for the Re complexes, torsional angle (X-Re-Re-X dihedral angle). Resonance Raman studies show that increasing pressure engenders an increase in the frequency of the metal-metal stretching mode for all of the species studied, and this change is empirically correlated with a decrease in metal-metal bond length. Large red shifts in the energy of the {sup 1}({delta} {yields} {delta}*) transitions with increased pressure for Re{sub 2}Br{sub 8}{sup 2{minus}} and Re{sub 2}Cl{sub 8}{sup 2{minus}}, in contrast to the relative insensitivity of Re{sub 2}F{sub 8}{sup 2{minus}} absorption and Mo{sub 2}Cl{sub 4}(PMe{sub 3}){sub 4} fluorescence transitions, imply a tendency for the former complexes to distort torsionally from an eclipsed configuration toward a staggered configuration due to pressure-induced steric repulsion of the chloride and bromide ligands. Integrated absorption intensities further show that, at higher pressures, even Re{sub 2}F{sub 8}{sup 2{minus}} undergoes some torsional distortion, whereas the steric repulsion of adjacent phosphines located at a 90{degree} dihedral angle on opposite Mo atoms prevents Mo{sub 2}Cl{sub 4}(PMe{sub 3}){sub 4} from distorting along the torsional coordinate. 28 refs., 7 figs., 1 tab.
- OSTI ID:
- 6358584
- Journal Information:
- Inorganic Chemistry; (USA), Vol. 29:18; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKANES
CHEMICAL PREPARATION
BROMINE COMPOUNDS
CHLORINE COMPOUNDS
FLUORINE COMPOUNDS
MOLYBDENUM COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
RHENIUM COMPLEXES
EXPERIMENTAL DATA
HIGH PRESSURE
RAMAN SPECTRA
COMPLEXES
DATA
HALOGEN COMPOUNDS
HYDROCARBONS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
REFRACTORY METAL COMPOUNDS
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties