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.