Co-ordination chemistry of a P,O-donor ligand: Synthesis of new complexes of Ru, Rh and Ir containing Ph(2)PNHP(O)Ph(2) or [Ph(2)PNP(O)Ph(2)](-)

Methylation of the monoxide Ph(2)PNHP(O)Ph(2) (HL) with MeI in tetrahydrofuran afforded [{Ph(2)P(Me)NP(O)Ph(2)}H-2]I which contains a symmetrical hydrogen bond, whereas benzylation with PhCH(2)Br gave [Ph(2)P(CH(2)Ph)NP(OH)Ph(2)]Br. The compound HL can be complexed, as a monodentate P-bound ligand, to various metal centres (Ru-II, Ru-IV, Rh-III and Ir-III). These compounds are excellent precursors for the construction of new five-membered metallacycles containing either M-P-N(H)-P-O or M-P-N-P-O rings. Treatment of [Ir{Ph(2)PNHP(O)Ph(2)-P,0}(cod)][BF4] (cod = cycloocta-1,5-diene) with an excess of MeI gave the oxidative addition compound [Ir{Ph(2)PNHP(O)Ph(2)-P,0}(cod)][BF4] in which a cis configuration of the iodide and methyl ligands is tentatively assigned. Deprotonation of it with NEt(3) gave the known neutral iridium(III) complex [IrI(Me){Ph(2)PNP(O)Ph(2)-P,0}(cod)]. All compounds were characterised by a combination of P-31-{H-1} and H-1 NMR spectroscopy, IR spectroscopy and microanalysis. The solid-state structures of [{Ph(2)P(Me)NP(O)Ph(2)}H-2]I, [Ph(2)P(CH(2)Ph)NP(OH)Ph(2)]Br, [Rh{Ph(2)PNHP(O)Ph(2)PNHP(O)Ph(2)-P,0}(cod)]-[BF4]. 0.33CHCl(3) and [RuCl{Ph(2)PNP(O)Ph(2)-P,0}(eta(6)-p-MeC(6)H(4)Pr(i))] have been elucidated by X-ray crystallography. The two complexes contain the P,O-chelating ligand Ph(2)PNHP(O)Ph(2) and [Ph(2)PNP(O)Ph(2)](-) respectively. With the exception of the rhodium complex the P-N-P-O fragments all show pi-electron delocalisation.