STERIC CONTRIBUTIONS TO THE SOLUTION DYNAMICS INVOLVING PHOSPHORUS LIGAND DISSOCIATION IN SUBSTITUTED DERIVATIVES OF MOLYBDENUM HEXACARBONYL

Kinetic and mechanistic studies of cis-Mo(CO)4L2 derivatives (L=phosphine or phosphite) are presented for the substitution reaction of one of the ligands (L) by carbon monoxide. These processes were observed to proceed by a dissociative mechanism with the rate of substitution being greatly enhanced as the size of the phosphorus ligand increases within a series of phosphine or phosphite derivatives. The cis-Mo(CO)4L2 species were found to react stereospecifically with 13CO to afford cis-Mo(CO)4(13CO)L derivatives. In addition, the [Mo(CO)4L] intermediate produced by phosphine loss from a stereospecifically 13CO-labeled cis-Mo(CO)4L2 derivative was observed to be nonfluxional during its solution lifetime. Rate studies of phosphine dissociation in trans-Mo(CO)4(PPh3)2 are reported which demonstrate this process to be less facile when compared with the analogous process in cis-Mo(CO)4(PPh3)2. Observations on the cis trans isomerization reaction of Mo(CO)4(PPh3)2 resulting from dissociative phosphine loss are also discussed. 1979, American Chemical Society. All rights reserved.

STERIC CONTRIBUTIONS TO THE SOLUTION DYNAMICS INVOLVING PHOSPHORUS LIGAND DISSOCIATION IN SUBSTITUTED DERIVATIVES OF MOLYBDENUM HEXACARBONYL Academic Article