Late transition-metal complexes of [Ph2P(O)NP(E)Ph-2](-) (E = S or Se) with a P,N-hybrid ligand: synthesis and structure

The unsymmetrical ligands [Ph2P(O)NP(E)Ph-2](-) (E = S or Se) adopt a range of ligation modes (O,E-chelate, E-monodentate and as a non-co-ordinating anion) upon reaction with selected late transition-metal tertiary phosphine complexes. Hence treatment of cis-[PtCl2(PPh3)(2)] with K[Ph2P(O)NP(E)Ph-2] in methanol gave the expected six-membered O,E-chelate complexes [Pt(PPh3)(2){Ph2P(O)NP(E)Ph-2-O,E}](+) isolated as their hexafluorophosphate salts. When [Pt(Ph2PC6H4NH2-P,N)(2)] Cl-2 was allowed to react under analogous conditions the monocationic mixed complexes [Pt(Ph2PC6H4NH-P,N)(Ph2PC6H4NH2-P,N)][Ph2P(O)NP(E)Ph-2] were obtained in excellent yields (> 90%). Reaction of [Pd(Ph2PC6H4NH2-P,N)(2)]Cl-2 with K[Ph2P(O)NP(S)Ph-2] (1 : 2 molar ratio) gave a mixture of three products identified by P-31-{H-1) NMR as [Pd(Ph2PC6H4NH-P,N) (Ph2PC6H4NH2-P,N)]Ph2P(O)NP(S)Ph-2], [Pd(Ph2PC6H4NH-P,N){Ph2P(O)NP(S)Ph-2-O,S}] (P trans to O) and Ph2PC6H4NH2. Alternatively the neutral compound [Pd(Ph2PC6H4NH-P,N){Ph2P(O)NP(S)Ph-2-O,S}] was synthesised in moderate yield from [PdCl2(Ph2PC6H4NH2-P,N)] and two equivalents of K[Ph2P(O)NP(S)Ph-2]. Chloride metathesis of [Pt(X)Cl(Ph2PC6H4NH2-P,N)] (X = CH3 or Cl) with K[Ph2P(O)NP(E)Ph-2] gave a series of platinum(II) complexes [Pt(X){Ph2P(O)NP(E)Ph-2-E}(Ph2PC6H4NH2-P,N)] (P trans to E) in which the anion adopts an E-monodentate co-ordination mode. The gold(I) complexes [AuCl(PPh3)] and [AuCl(Ph2PC6H4NH2)] undergo smooth substitution reactions with K[Ph2P(O)NP(E)Ph-2] to give [Au(Ph2P(O)NP(E)Ph-2-E)(PPh3)] and [Au{Ph2P(O)NP(E)Ph-2-E}(Ph2PC6H4NH2)] respectively. All new compounds have been characterised by a combination of multinuclear NMR [H-1, P-31-{H-1} and Pt-195-{H-1}], IR spectroscopy and elemental analyses. The molecular structures of four examples have been determined by single-crystal X-ray crystallography and furthermore reveal intra- and inter-molecular PE ... H-N hydrogen bonding arrangements. There is also evidence for pi-delocalisation within the E-P-N-P-O backbone.