Dedicated to Professor Marianne Baudler on the occasion ofher 75th birthday
The development of transition metal complexes with one cyclopentadienyl ligand and halogeno ligands is of great interest, since these compounds can be used as readily accessible precursors in the synthesis of numerous organometallic compounds containing metals in both low and high oxidation states."] Since the discovery of the pentamethylcyclopentadienyl-substituted metal chlorides [C~*MOCI,][~~ and [CP*WCI,]'~' (Cp* = $-C,Me,), many monocyclopentadienyl compounds of molybdenum and tungsten have been prepared in which the metal atoms are present in the formal oxidation states +HI and +v. The synthesis of compounds containing molybdenum in the rarely observed f i v oxidation state was only achieved very recentIy.14 -61 We report herein on the synthesis of the first fluorinated pentamethylcyclopentadienyltungsten complexes [Cp*WF,] 1, [($-C,Me,Et)WF,] 2, [Cp*WF,(thf)] 3, and [Cp*WF,] 4, as well as on the crystal structure of the tungsten(v1) fluoride. Within the context of our investigations on cyclopentadienyl-(fluoro) transition metal complexes, we have shown that by using trimethyltin fluoride['' as a metathetically acting fluorinating reagent it is possible to prepare organometallic fluorides of Group 4 of the type [Cp*MF3] (M = Ti, Zr, Hf) as well as main group element fluorides such as PF, and SOF, .[81 Herein we report that these fluorinating reagents can be used to synthesize completely new cyclopentadienyl fluorides of Group 6. The reaction of the tetrachloro complexes [ ($-C,Me,R)-WCl,] (R = Me.Et) with trimethyltin fluoride in the molar ratio 1 :4 leads to the fluorides [Cp*WF,] 1 and [(q'-C,Me,Et)WF,] 2 [Eq. (a)]. The trimethyltin chloride formed during the reaction W + 4 Me3SnF 4 Me3SnC1 .* F' / W LF"F (a)