[CP2V(MU-ETA(2) ETA(4)-BUTADIYNE)MCP2'] (M = TI, ZR, CP' = C5H5, C5H4SIME3) - HETERODIMETALLIC COMPLEXES FROM A BIS(ALKYNYL)METALLOCENE ANDVANADOCENE - UNEXPECTED STRUCTURE OF [CP2V(MU-ETA(2)/ETA(4)-BUTADIYNE)ZR(C5H4SIME3)(2)] CONTAINING 2 PLANAR-TETRACOORDINATE CARBON-ATOMS/

The reaction of [Cp2Ti(C=CPh)(2)] [Cp2Zr(C=CPh)(2)], or [(C5H4SiMe3)(2 )Zr(C=CPh)(2)] with vanadocene in toluene at room temperature gives [C p2V(mu-eta(2):eta(4)-butadiyne)MCp2'] 1 (M = Ti, Cp' = C5H5), 2 (M = Z r, Cp' = C5H5), or 3 (M=Zr, Cp'-C5H4SiMe3), respectively. These compou nds, which have been characterized by elemental analysis, mass spectro metry, IR and Raman spectroscopy, exhibit similar magnetic susceptibil ities. According to an X-ray diffraction analysis of 3, the [Cp2V] and Cp-2'Zr metallocene moieties are bonded to a butadiene (or butadiyne) framework through the two internal carbon atoms for [Cp2V], and thoug h the two internal and the two external carbon atoms for [Cp-2'Zr]. Th e two internal carbon atoms of the butadiene skeleton are planar and t etracoordinated.