New E-unidentate [Ph₂P(O)NP(E)Ph₂]- (E = S or Se) complexes of palladium(II) and platinum(II)

Metathesis of the monochloro metal(II) complexes [MCl(dien)] Cl (M=Pd or Pt; dien=diethylenetriamine) with K[Ph2P(O)-NP(E)Ph-2] (E=S or Se) or K[Ph2P(O) NPPh2] (prepared in situ from Ph2P(O)NHPPh2/KOBut) in methanol gave the cationic, mononuclear compounds [M(Ph2P(O)NP(E)Ph-2-E)(dien)](+) or [M(Ph2P(O)NPPh2-P)(dien)](+), isolated as their hexafluorophosphate salts. Ligand substitution reactions of the dichlorometal(II) precursors [MCl2(N similar to N)] (M = Pd or Pt; N similar to N = ethane-1,2-diamine, 1,2-diaminocyclohexane) with K[Ph2P(O)NP(E)Ph-2] or K[Ph2P(O)NPPh2] gave the neutral his substituted compounds [M{Ph2P(O)NP(E)Ph-2-E}(2)(N similar to N)] or [M{Ph2P(O)NPPh2-P}(2)(N similar to N)] in high yields (63-89%). Reaction of the unsymmetrical palladium(II) compound [PdCl2(ampy)] (ampy = 2-aminomethylpyridine) with K[Ph2P(O)NP(E)Ph-2] gave [Pd{Ph2P(O)NP(E)Ph-2-E}(2)(ampy)], analogous to the recently described compound [Pd{Ph2P(O)NP(E)Ph-2-E}(2)(en)], in which both [Ph2P(O)NP(E)Ph-2](-) ligands are exclusively E-monodentate bound. In contrast, transmetallation of K[Ph2P(O)NP(E)Ph-2] with [PdCl2(tmeda)] (tmeda =N,N,N',N'-tetramethylethylenediamine) gave only the O,E-chelate monocationic complexes [Pd{Ph2P(O)NP(E)Ph-2-O,E}(tmeda)]PF6 and not [Pd{Ph2P(O)NP(E)Ph-2-E}(2)(tmeda)]. Under similar reaction conditions the symmetrical anions [Ph2P(E)NP(E)Ph-2](-) (E=S or Se) gave, without exception, the known bis homoleptic complexes [M{Ph2P(E)NP(E)Ph-2-E,E'}(2)] (M=Pd or Pt) with displacement of all chloride and amine ligands. All new compounds have been characterised by a combination of multinuclear NMR (H-1, P-31{H-1}, Pt-195{H-1}), IR spectroscopy and elemental analyses. Furthermore, the X-ray crystal structures of five compounds have been determined and reveal a range of intermolecular and intramolecular hydrogen bonding contacts. There is also evidence for pi-delocalisation within the E-P-N-P-O and P-N-P-O backbones of the E-ligating or O,E-chelating ligand. (C) 2000 Elsevier Science Ltd All rights reserved.