A carbon-13 NMR study of some pentacarbonylrhenium complexes

Abstract

Carbon-13 NMR data are reported for derivatives XRe(CO) 5 (X = CH 3, CH 3CO, C 6H 5, C 6H 5CO, Br, Cl 3Si, Me 3Si, Me 3Ge, Me 3Sn, Me 3Pb). Spectra of good quality were obtained at ambient temperature except for X = Me 3Pb. In the XRe(CO) 5 series, the carbonyl carbon trans to X is more shielded (resonance at higher field) than carbonyl carbons cis to X. However, in the cationic complex [CH 3CHRe(CO) 5][PF 6], the carbonyl carbon trans to CH 3CN is less shielded than those in cis positions. Although there is a linear relation between the 13C chemical shift and the stretching force constant for cis carbonyls in the XRe(CO) 5 series, there is no apparent correlation of force constants with other features of the 13C NMR spectra.