Substitution Reactions of (C5Ph5)Cr(CO)3:  Structural, Electrochemical, and Spectroscopic Characterization of (C5Ph5)Cr(CO)2L (L = PMe3, PMe2Ph, P(OMe)3)

• Published in: Organometallics Vol. 15; no. 22; pp. 4791 - 4797
• Main Authors: Hammack, D. John, Dillard, Mills M, Castellani, Michael P, Rheingold, Arnold L, Rieger, Anne L, Rieger, Philip H
• Format: Journal Article
• Language: English
• Published: American Chemical Society 29.10.1996
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om960374u

The radical complex (C5Ph5)Cr(CO)3 reacts with small, neutral, monodentate Lewis bases (PMe3, PMe2Ph, P(OMe)3) in THF at −78 °C (PMe2Ph reacts at ambient temperature) to yield the monomeric substitution products (C5Ph5)Cr(CO)2L·THF as thermally stable solids. Electrochemical and spectroscopic data are provided. An X-ray crystal structure of the hemisolvate (C5Ph5)Cr(CO)2PMe3·0.5THF was obtained. Frozen-solution ESR spectra of (C5Ph5)Cr(CO)2L in toluene are comparable to those of other low-spin d5 “piano-stool” complexes. Rotation of the Cr(CO)2L moiety relative to the C5Ph5 ring is rapid on the ESR time scale in low-temperature liquid solutions and leads to axial powderlike spectra. Analysis of this effect leads to significant insights into the electronic structure.