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 KOBu^t 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 KOBu^t(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 KOBu^t 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.