Synthesis and NMR investigation of Pt(CN)2(diphosphine) and [Pt(CN)(triphosphine)]Cl complexes

Pt(CN)2(Ph2P(CH2)nPPh2) (n=2,3,4) and Pt(CN)2(P1P2) (P1P2=1-diphenylphosphino-2,1′-[(1-diphenylphosphino)-1,3-propanediyl]-ferrocene, 1-diphenylphosphino-2,1′-[(1-dicyclohexylphosphino)-1,3-propanediyl]-ferrocene) were synthesised by reacting potassium cyanide and the corresponding PtCl2(diphosphine) complexes. PtCl(CN)(diphosphine) complexes were identified as minor products when KCN/PtCl2(diphosphine) molar ratio was kept below 2. The use of KCN in excess resulted in the formation of K2Pt(CN)4. [Pt(CN)({Ph2P(CH2)2}2PPh)]+ complex cation and Pt(CN)2)({Ph2P(CH2)2}2PPh) five-coordinate covalent complex of fluxional behaviour were obtained at KCN/Pt ratio of 1 and 2, respectively. The platinum–cyano complexes were characterised by NMR spectroscopy. The direct PtCN bond was proved by 1J(195Pt,31P), 2J(31P,13C) coupling constants by using sodium cyanide-13C for ligand exchange reactions.