C-Metalated Diazoalkane Complexes of Platinum Based on PCP- and PCN-Type Ligands

A series of the first C-metalated diazoalkane complexes of Pt, based on pincer-type PCN and PCP ligands (PCP = C 6 H 3 [CH 2 P(iPr) 2 ] 2; PCN = C 6 H 3 [CH 2 P(tBu) 2 ](CH 2 ) 2 N(CH 3 ) 2 ), with the general formula (PCX)Pt[C(N 2 )R] ( 2, X = N, R = Ph; 3, X = N, R = SiMe 3; 5, X = P, R = Ph) were prepared via direct nucleophilic attack of RCN 2 - Li + at the metal center. These remarkably stable complexes were characterized by 1 H, 31 P{ 1 H}, and 13 C NMR and IR spectroscopy. Complex 2 was also characterized by single-crystal X-ray crystallography. Reactions of the C-metalated diazoalkane Pt complexes with Cu(I) (reported to catalyze decomposition of diazoalkanes) were strongly influenced by the nature of the pincer ligand. Bimolecular coupling to generate diphenylacetylene and (PCP)Pt−OTf ( 6 ) was observed in the case of the rigid PCP-based complex 5, while the hemilabile PCN-based complex 2 was converted to an ylide-bridged dimeric structure, the formation of which was promoted by the decoordination of the ligand amine arm. In addition, formation of the stable metal-substituted azine-type binuclear complex 10, generated by reaction of 2 with Rh 2 (OAc) 4, is described.