Complexes of [Ph2P(O)NP(E)Ph2]–(E = S or Se): disparate ring conformations within a new palladacycle
Abstract
A new mixed oxygen–selenium ligand Ph2P(O)NHP(Se)Ph2, its potassium salt K[Ph2P(O)NP(Se)Ph2] and the bis(chelate) palladium(II) complex cis-[Pd{Ph2P(O)NP(Se)Ph2-O,Se}2] have been prepared. In cis-[Pd{Ph2P(O)NP(Se)Ph2-O,Se}2] the two cis six-membered Pd–O–P–N–P–Se rings adopt different conformations: one is a pseudo-boat whilst the other is chair-like (X-ray evidence). Reaction of 2 equivalents of K[Ph2P(O)NP(Se)Ph2] with [PtCl2(cod)](cod = cycloocta-1,5-diene) in MeOH, or more conveniently using the methoxo-bridged platinum(II) dimer [{Pt(µ-OMe)(C8H12OMe)}2](C8H12OMe = 8-methoxycyclooct-4-en1-yl), afforded [Pt(C8H12OMe){Ph2P(O)NP(Se)Ph2-O,Se}] as one isomer only. The mixed oxygen–sulfur salt K[Ph2P(O)NP(S)Ph2] was used to prepare similar compounds, all of which have been characterised by a combination of multinuclear NMR (31P-{1H}, 195Pt-{1H} and 1H), IR spectroscopy and microanalysis. The molecular structures of Ph2P(O)NHP(S)Ph2, cis-[Pd{Ph2P(O)NP(Se)Ph2-O,Se}2] and [Pt(C8H12OMe){Ph2P(O)NP(S)Ph2-O,S}] have been determined by single-crystal X-ray diffraction.