Synthesis and x-ray structures of some homonuclear μ-alkylidenetungsten complexes

Abstract

The complexes W 2{μ-CHCHC(CH 3) 2](CO) 10} and W 2{μ-CHCHC(CH 3)(CH 2) 3CH 3][(CO) 10} have been synthesized, and an X-ray diffraction study has revealed the presence of five CO groups on each metal center. The analogy between W 2{μ-CHCHC(CH 3) 2][(CO) 9]} anda complex of W(CO) 4 and a tungstabutadiene (CO) 5WCHCHC(CCH 3) 2 prompted the synthesis of the first heteroatom-substitued μ-alkylidene complexes of tungsten, starting from conjugated Fischer-typ carbene complexes (CO) 5WC(OR)CHCHR. The X-ray structure of the complex W 2{μ-C(OEt)CHCH(CH 3)][(CO) 9]} has also been determined. In the case of the simplest conjugated compelx (CO) 5WC(OR)CHCH 2, an interesting rearrangement initiated by addition of W(CO) 5 to the terminal CC double bond giving a dinuclear complex W(CO) 5[η 2-CH 2CHC(OMe)W(CO) 5] in which the two metal centers are not directly linked, has been observed.