SUBSTITUTION-REACTIONS OF(C(5)PH(5))CR(CO)(3) - STRUCTURAL, ELECTROCHEMICAL, AND SPECTROSCOPIC CHARACTERIZATION OF (C(5)PH(5))CR(CO)(2)L (L=PME(3), PME(2)PH, P(OME)(3))

The radical complex (C(5)Ph(5))Cr(CO)(3) reacts with small, neutral, m onodentate Lewis bases (PMe(3), PMe(2)Ph, P(OMe)(3)) in THF at -78 deg rees C (PMe(2)Ph reacts at ambient temperature) to yield the monomeric substitution products (C(5)Ph(5))Cr(CO)(2)L . THF as thermally stable solids. Electrochemical and spectroscopic data are provided. An X-ray crystal structure of the hemisolvate (C(5)Ph(5))Cr(CO)(2)PMe(3) . 0.5 THF was obtained. Frozen-solution ESR spectra of (C(5)Ph(5))Cr(CO)(2)L in toluene are comparable to those of other low-spin d(5) ''piano-sto ol'' complexes. Rotation of the Cr(CO)(2)L moiety relative to the C(5) Ph(5) ring is rapid on the ESR time scale in low-temperature liquid so lutions and leads to axial powderlike spectra. Analysis of this effect leads to significant insights into the electronic structure.