Amine-functinalised aminophosphines: synthesis, reversible co-ordination to platinum and use in heteronuclear dimer formation

摘要

Amine functionalised aminophosphines Ph_2PN(R)CH_2CH_2NMe_2 (R = H L~1 or Me L~2) were prepared from the reaction of PPh_2Cl with NHRCH_2CH_2NMe_2 in the presence of the base n-butyllithium (L~1) or triethylamine (L~2). Reaction of two equivalents of L~(1,2) with [PtCl_2(cod)] gave the complexes cis-[PtCl_2L_2] (L = L~1 1 or L~2 2), which were shown to be fluxional with one of the amine groups reversibly co-ordinating to displace a chloride. Removal of a chloride in 1 by metathesis gave cis-[PtCl(L_1-P)(L~1 = P,N)]PF_6 3 which was not fluxional on the NMR timescale. Reaction of one equivalent of L~2 with [PtCl_2(cod)] gave the complex cis-[PtCl(L_2-P,N)] 4 in which L~2 is acting as a bidentate ligand. The reaction of L~2 with [{Pt(dmba)(#mu#-Cl)}_2] (Hdmba = N,N-dimethylbenzylamine) gave [Pt(dmba)Cl(L~2)] 5, which exists as a mixture of the two geometric isomers. Reaction of 5 with TlPF_6 gave [Pt(dmba)(L~2-P,N)]PF_6 6 as a single isomer in which the phosphorus atom is co-ordinated trans to the N,N-dimethylbenzylamine nitrogen atom. Complex 2 reacts with CoCl_2 (centre dot) 6H_2O and ZnCl_2 to give cis-[(L_2-P,N)ClPt(#mu#-L~2)MCl_3] (M = Co 7 or Zn 8). The zwitterionic structure of 7 was confirmed by a single-crystal X-ray analysis, which showed no metal-metal interaction between the platinum and cobalt centres.