Oxidation of an o -tolyl phosphine complex of platinum : C-H activation and transcyclometallation

The oxidation of the tri(o-tolyl)phospine complex of the doubly cyloplatinated 2,6-di(4-fluorophenyl)pyridine ligand with the electrophilic oxidant iodobenzenedichloride was studied. Three products were formed in the ratio 15:15:70, and all were identified. The simple cis-dichloro platinum(IV) complex 2 (15%) remained in solution and could be purified and fully characterised. The triply cyclometallated 3 (15%), formed via the activation of a methyl group on a tolyl ring, precipitated from the reaction mixture and could not be redissolved or characterised further. Transcyclometallated 4 (70%), where one of the original cyclometallated aryl rings has exchanged for a cyclometallated phosphine ring, crystallised from the reaction mixture and was characterised crystallographically. Redissolution of 4 gave a new agostic species with the phosphine moving to a less sterically demanding position