New platinum(II) complexes of Ph2PNHP(O)Ph2 and [Ph2PNP(O)Ph2]–
Abstract
Refluxing a suspension of cis-[PtCl2(HL)2][HL = Ph2PNHP(O)Ph2-P] in methanol for ca. 11 h led to Ph2P–N bond cleavage of one of the HL ligands and formation of cis-[PtCl2(HL)(Ph2POMe)]1. Prolonged refluxing of 1 in methanol (5 d) gave predominantly unchanged 1 in addition to some cis-[PtCl2(Ph2POMe)2]2 and cis-[PtCl(L)(Ph2POMe)]3[L = Ph2PNP(O)Ph2-P,O]. Reaction of 1 with KOBut afforded solely 3 in good yield. Bridge cleavage of [{PtCl(µ-Cl)(PMe2Ph)}2] with 2 equivalents of HL gave trans-[PtCl2(HL)(PMe2Ph)]4a which is smoothly isomerised to cis-[PtCl2(HL)(PMe2Ph)]4b upon addition of trace amounts of HL. Complexes 4a and 4b reacted with KOBut(ca. 1.4 equivalents) in methanol to yield trans- and cis-[PtCl(L)(PMe2Ph)]5a and 5b respectively. Choride abstraction of either 4a or 4b with Ag[BF4] in dichloromethane yielded the P,O-chelate cationic complexes trans-(6a) or cis-[PtCl(HL)(PMe2Ph)][BF4]6b respectively. Further reaction of 5b with KOBut in methanol gave the hydroxide-bridged platinum(II) dimer [{Pt(µ-OH)L(PMe2Ph)}2]7 in which the P-donor atom in L is co-ordinated to the platinum(II) centre and the O-donor atom is involved in an intramolecular hydrogen bond to the hydroxide ligand (X-ray evidence). All the compounds 1–7 have been characterised by a combination of 31P-{1H} and 195Pt-{1H} NMR, IR spectroscopy and microanalysis. Furthemore the solid-state structures of cis-[PtCl2(HL)(PMe2Ph)], the geometric isomers trans- and cis-[PtCl(L)(PMe2Ph)] and [{Pt(µ-OH)L(PMe2Ph)}2] have been determined by single-crystal X-ray diffraction.