Synthesis, structure, and hydride-deuteride exchange studies of CpMoH{sub 3}(PMe{sub 2}Ph){sub 2} and theoretical studied of the CpMoH{sub 3}(PMe{sub 3}){sub 2} model system
- Univ. of Maryland, College Park, MD (United States)
- Texas A&M Univ., College Station, TX (United States)
The synthesis and characterization of CpMoH{sub 3}(PMe{sub 2}Ph){sub 2}, 1, is described. Compound 1 is obtained from the reaction between CpMoCl{sub 3}, PMe{sub 2}Ph, and LiAlH{sub 4}, in 61% yield. Compounds 1 has also been obtained from the reaction of CpMo(o-C{sub 6}H{sub 4}PMe{sub 2}) (PMe{sub 2}Ph){sub 2} with H{sub 2}. Characterization of 1 by {sup 1}H- and {sup 31}P-NMR spectroscopies shows a high degree of fluxionality for the hydride atoms, even at low temperatures. A single-crystal X-ray structure indicates that the geometry is pseudo-octahedral, with a relative mer arrangement of three H ligands and the two PMe{sub 2}Ph ligands occupying relative trans positions. This is in contrast with the only other previously reported structure of a Mo(IV) trihydride, Cp{sup *}MoH{sub 3}(dppe), which adopts a pseudo trigonal prismatic structure. The Mo-P (average 2.41(8) A) and Mo0H distances (average 1.64(4) A) are similar to those found in Cp{sup *}MoH{sub 3}(dppe). The closest H-H distance is 1.79 A, consistent with a classical hydride. The results of ab initio calculations for the CpMoH{sub 3}(PMe{sub 3}){sub 2} model in different configurations agree with the experimental observations and suggest that a mechanism of hydride exchange consisting of a Bailar twist, which interconverts pseudo-octahedral mer, trans and fac geometries, is possible. The process of hydride-deuteride exchange of 1 in C{sub 6}D{sub 6} is also examined. 50 refs., 2 figs., 5 tabs.
- OSTI ID:
- 484665
- Journal Information:
- Organometallics, Vol. 16, Issue 6; Other Information: PBD: 18 Mar 1997
- Country of Publication:
- United States
- Language:
- English
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