Synthesis and transition metal chemistry of a bridging diphosphinite, 1,4 bis(diphenylphosphinoxy)benzene

Diphosphinite ligand, [Ph2POC6H4OPPh2] (1), is obtained by reacting chloro diphenylphosphine, with 1,4-dihydroxy benzene in presence of triethylamine. Treatment of 1 with elemental sulfur or selenium resulted in the formation of bis(chalcogenide) derivatives, [Ph2(E)POC6H4OP(E)Ph2] (2, E = S; 3, E = Se) in almost quantitative yield. The binuclear complex [{(η6-p-cymene)RuCl2}2(Ph2POC6H4OPPh2)] (4) is produced in the reaction between [Ru(η6-p-cymene)Cl2]2 and diphosphinite 1. Similarly the reaction of 1 with [Rh(COD)Cl]2 afforded a binuclear complex [{(COD)RhCl}2(Ph2POC6H4OPPh2)] (5), whereas the macrocyclic complex [{(CO)RhCl}(Ph2POC6H4OPPh2)]2 (6) is isolated in the reaction of 1 with 0.5 equiv of [RhCl(CO)2]2. Compound 1 on treatment with [Pd(COD)Cl2] or [PdCl2(SMe2)2] in 1:1 molar ratio produced the chloro-bridged binuclear complex [{(PPh2O)Pd(μ-Cl)(PPh2OH)}2] (7) through P–O bond cleavage. Treatment of 1 with two equivalents of CuI in dichlormethane/acetonitrile (1:1) afforded a coordination polymer, [{Cu2(μ-I)2(Ph2POC6H4OPPh2)}∞] (8) in moderate yield. The binuclear complex, [{AuCl}2(μ-Ph2POC6H4OPPh2)] (9) is obtained in the reaction of compound 1 with two equiv of AuCl(SMe2), where the ligand exhibits bridged bidentate mode of coordination. The molecular structures of 1–4, and 6 are determined by X-ray diffraction studies.

Graphical abstractThe transition metal chemistry and reactivity of a bridging diphosphinite, 1,4 Bis(diphenylphosphinoxy)benzene is described.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The ligands are ideal for supramolecular structures and coordination polymers. ► They can readily form supramolecular structures with low-valent transition metals. ► May be useful in homogeneous catalysis. ► The bis(phosphinite) is a moderate π-acceptor ligand.