CRYSTAL-STRUCTURE OF [W(ETA-C6F6)2] SYNTHESIZED TOGETHER WITH OTHER SANDWICH COMPLEXES OF TUNGSTEN AND MOLYBDENUM-CONTAINING ETA(6)-C6F6 OR ETA(6)-C6H3F3-1,3,5 LIGANDS, FROM ATOMS OF THE METALS

Reaction of molybdenum or tungsten atoms with hexafluorobenzene or 1,3,5-trifluorobenzene or with mixtures of these ligands and benzene or 1,3,5-trimethylbenzene gave the new compounds [M(C6F6)2], [M(C6H3F3-1,3,5)2], [M(C6F6)(C6H6)], [M(C6F6)(C6H3F3-1,3,5)] and [M(C6F6)(C6H3Me3-1,3,5)] (M = Mo or W) in yields ranging from < 1 to 5% as stable crystalline solids. A single-crystal X-ray study of [W(C6F6)2] showed it to have the same symmetry as [Cr(C6H6)2] and the same W-C bond lengths as in [W(C6H5Me)2]. The F-19 and H-1 NMR spectra of the mixed-ligand products show inter-ring coupling with large coupling constants which make some of the spectra exceptionally easy to interpret.