New E-unidentate [Ph 2P(O)NP(E)Ph 2] − (E=S or Se) complexes of palladium(II) and platinum(II)

Abstract

Metathesis of the monochloro metal(II) complexes [MCl(dien)]Cl (M=Pd or Pt; dien=diethylenetriamine) with K[Ph 2P(O)NP(E)Ph 2] (E=S or Se) or K[Ph 2P(O)NPPh 2] (prepared in situ from Ph 2P(O)NHPPh 2/KOBu t) in methanol gave the cationic, mononuclear compounds [M{Ph 2P(O)NP(E)Ph 2- E}(dien)] + or [M{Ph 2P(O)NPPh 2- P}(dien)] +, isolated as their hexafluorophosphate salts. Ligand substitution reactions of the dichlorometal(II) precursors [MCl 2(N∼N)] (M=Pd or Pt; N∼N=ethane-1,2-diamine, 1,2-diaminocyclohexane) with K[Ph 2P(O)NP(E)Ph 2] or K[Ph 2P(O)NPPh 2] gave the neutral bis substituted compounds [M{Ph 2P(O)NP(E)Ph 2- E} 2(N∼N)] or [M{Ph 2P(O)NPPh 2- P} 2(N∼N)] in high yields (63–89%). Reaction of the unsymmetrical palladium(II) compound [PdCl 2(ampy)] (ampy=2-aminomethylpyridine) with K[Ph 2P(O)NP(E)Ph 2] gave [Pd{Ph 2P(O)NP(E)Ph 2- E} 2(ampy)], analogous to the recently described compound [Pd{Ph 2P(O)NP(E)Ph 2- E} 2(en)], in which both [Ph 2P(O)NP(E)Ph 2] − ligands are exclusively E-monodentate bound. In contrast, transmetallation of K[Ph 2P(O)NP(E)Ph 2] with [PdCl 2(tmeda)] (tmeda= N,N,N′,N′-tetramethylethylenediamine) gave only the O,E-chelate monocationic complexes [Pd{Ph 2P(O)NP(E)Ph 2- O,E}(tmeda)]PF 6 and not [Pd{Ph 2P(O)NP(E)Ph 2- E} 2(tmeda)]. Under similar reaction conditions the symmetrical anions [Ph 2P(E)NP(E)Ph 2] − (E=S or Se) gave, without exception, the known bis homoleptic complexes [M{Ph 2P(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 ( 1H, 31P{ 1H}, 195Pt{ 1H}), 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 π-delocalisation within the E–P–N–P–O and P–N–P–O backbones of the E-ligating or O,E-chelating ligand.