Synthesis and characterisation of the first E-unidentate [Ph2P(O)NP(E)Ph2]– metal complexes [Au{Ph2P(O)NP(E)Ph2-E}{Ph2P(O)NHPPh2}] and [Pd{Ph2P(O)NP(E)Ph2-E}2(H2NCH2CH2NH2)] (E = S or Se)

Chloride metathesis of [AuCl(HL)] [HL = Ph2P(O)NHPPh2] or [PdCl2(en)] (en = ethane-1,2-diamine) in CH3OH with either 1 (or 2) equivalents of [Ph2P(O)NP(E)Ph2]– (E = S or Se) gave the neutral compounds [Au{Ph2P(O)NP(E)Ph2-E}(HL)] or [Pd{Ph2P(O)NP(E)Ph2-E}2(en)] respectively; the anionic ligands in these complexes adopt a new bonding mode and furthermore are involved in intramolecular N–H· · ·OP hydrogen bonding with HL or en.