Preparation of trichloro- and tribromocyclopentadienyltungsten(IV)

International audience; The thermal decarbonylation of (Ring)WX3(CO)2 in refluxing toluene has led to the preparation of the CO-free compounds [(Ring)WX3]2 [Ring=η5-C5H5 (Cp) and X=Cl (1a) or Br (1b); Ring=η5-C5H4Me (Cp′), X=Cl (2a) or Br (2b); Ring=η5-C5Me5 (Cp*), X=Cl (3)]. The NMR properties of these molecules are consistent with diamagnetism and thereby indicate a different structure from that of the paramagnetic molybdenum analogues. Compounds 1a and 2a react with dppe to afford mononuclear 18-electron adducts, (Ring)WCl3(dppe) (Ring=Cp (4) or Cp′ (5)). The X-ray structure of 5 shows a pseudo-fac-octahedral geometry with the dppe ligand occupying two equatorial (e.g. cis relative to Cp…