Co-ordination chemistry of molybdenum. Part II. Oxomolybdenum(IV) and -(V) complexes of diphosphine, diarsine, and arsine-phosphine ligands

Abstract

Reaction of [MoCl₃O(thf)₂](thf = tetrahydrofuran) with bidentate ligands [L–L = Ph₂PCH₂CH₂PPh₂(dppe); Ph₂AsCH₂CH₂AsPh₂(dpae); cis-Ph₂PCHCHPPh₂(dppen); cis-Ph₂AsCHCHAsPh₂(dpaen) : Ph₂AsCH₂CH₂PPh₂(dadpn); cis-Ph₂AsCHCHPPh₂(dadpen); C₆H₄(PPh₂-o)₂(pdpp); and C₆H₄(AsPh₂-o)(PPh₂-o)(pdadp)] has led to the isolation of [MoCl₃O(L–L)] complexes. Refluxing these complexes in methanol leads to partial reduction to form [Mo^IVClO(L–L)₂][Mo^VCl₄O], but reflux in methanol in the presence of L–L and Na[BPh₄] results in complete reduction to [MoClO(L–L)₂][BPh₄]. These complexes have been characterised by the use of i.r., electronic-absorption, and e.p.r. spectroscopy. E.p.r. spectra suggest that the [MoCl₃O(L–L)](L–L = dppe or dppen) species have a fac structure in dichloromethane. Considerable hyperfine structure, and g values ca. 1.97, have been observed for the e.p.r.-active species.