Synthesis and Characterisation of W VI Complexes of Phosphane Oxide Ligands, [WO 2 X 2 (OPR 3 ) 2 ] (X = F, Cl or Br; R = Me or Ph), and of the [MoO 2 F 2 (OPR 3 ) 2 ]

Phosphane oxide complexes of dioxidotungsten VI , [WO 2 X 2 (OPR 3 ) 2 ] (X = Cl or Br, M = Ph or Me) have been prepared under anhydrous conditions from the reaction of WX 6 with (Me 3 Si) 2 O in CH 2 Cl 2 , followed by addition of OPR 3 . Some diphosphane dioxide analogues have been made similarly, viz, [WO 2 X 2 (L–L)] {L–L = Ph 2 P(O)(CH 2 ) n P(O)Ph 2 ( n = 1 or 2), o ‐C 6 H 4 [P(O)Ph 2 ] 2 }. The complexes have been characterised by elemental analysis, IR and NMR ( 1 H and 31 P{ 1 H}) spectroscopy, and the structures of [WO 2 Br 2 (OPPh 3 ) 2 ] and [WO 2 Cl 2 (OPMe 3 ) 2 ] determined, revealing distorted six‐coordinate tungsten centres with cis ‐WO 2 and trans ‐WX 2 units. The difluorido‐dioxido complexes [MO 2 F 2 (OPR 3 ) 2 ] (M = Mo or W) and [WO 2 F 2 (L′–L′)] (L′–L′ = 2,2′‐bipyridyl, 1,10‐phenanthroline) have been prepared by fluorination of the corresponding chlorido complexes with Me 3 SnF in CH 2 Cl 2 . These are characterised similarly and by 19 F{ 1 H} NMR spectroscopy. Attempts to make [MO 2 I 2 (OPR 3 ) 2 ] were unsuccessful. No adduct formation occurs between CrO 2 Cl 2 and OPPh 3 under rigorously anhydrous conditions. Crystal structures of [Me 3 SnCl(OPPh 3 )] and two forms of [WO 2 Cl 2 (1,10‐phen)] are also reported and discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)