Synthesis and structure of [(η5-C5Me5)WCl2(μ-H)]2. A dinuclear tungsten hydride with a double bond formed from the reaction of BH3THF with (η5-C5Me5)WCl4

The reaction of limited quantities of BH3THF with Cp*WCl4, Cp*=η5-C5Me5, leads to the formation of [Cp*WCl2(μ-H)]2 and BH2Cl in good yield. Structural characterization by spectroscopic and crystallographic techniques reveals the presence of two Cp*WCl2 fragments in a transoid arrangement connected by a formal WW double bond (dWW=2.5150(5) Å) bridged by two hydrogen atoms. Reaction of [Cp*WCl2(μ-H)]2 with additional BH3THF leads ultimately to Cp*2W2B5H9, thereby providing information on the role of [Cp*WCl2(μ-H)]2 as an intermediate in the formation of Cp*2W2B5H9 from the reaction of Cp*WCl4 with an excess of BH3THF.