European journal of inorganic chemistry issue:1 pages:107-115
Ab initio MO and DFT calculations have been performed on phosphinidene complexes of the type Cr(CO)(5)-PR, with R = H-r CH3, SiH3, NH2, PH2, OH, and SH. The formation of the Cr-P bond essentially arises from a ligand-to-metal charge transfer. While a significant pi backdonation is also observed for the Cr(CO)S-PH, Cr(CO)(5)-PCH3, and Cr(CO)(5)-PSiH3 complexes, this is less the case for Cr(CO)(5)-POH, Cr(CO)(5)-PSHr and Cr(CO)(5)-PNH2, and the backbonding almost disappears for Cr(CO)(5)-PPH2. In both the lowest lying singlet and triplet states. all complexes exhibit a staggered conformation. CASSCF/CASPT2 calculations performed with the ANO basis sets indicate a closed-shell singlet ground state along the whole series. The binding energy between Cr(CO)(5) and PR ranges from 216 kJ/mol for Cr(CO)(5)-PNH2 to 127 kJ/mol for Cr(CO)(5)-PSiH3 (B3LYP values). In general, the B3LYP-DFT scheme yields reasonable qualitative and quantitative results when compared with CASPT2(12/12).