A NEW APPROACH FOR THE SYNTHESIS OF NEUTRAL AND ANIONIC ZIRCONOCENE ALDEHYDE COMPLEXES

To expand the availability of transition-metal aldehyde complexes for study, a new method for their synthesis has been developed. Our first application of this method has been to the synthesis of zirconocene eta2-aldehyde complexes. Proceeding through alpha-stannylalkoxide intermediates (M-OCHR-SnMe3), this route provides ready access to both neutral and anionic complexes under mild conditions. The first X-ray structure of an anionic aldehyde complex is reported. The neutral complexes dimerize producing meso and racemic diastereomers. Monomeric zirconaoxiranes are shown to be excluded from the reaction coordinate during insertion and isomerization reactions of these neutral complexes. (R,S)-[CP2Zr(eta2-OCHCH2CHMe2)]2 crystallizes in the monoclinic space group P2(1)/c with a = 9.7293(19) angstrom, b = 18.733(4) angstrom, c = 8.0984(13) angstrom, beta = 109.838(13)-degrees, and Z = 2. The refinement was carried out with 2496 observed room temperature reflections to give R(F) = 2.78% and R(w)(F) = 3.00%. {Cp2Zr(Me)(eta2-OCHCH2-CHMe2)Li}2(C4H8O) crystallizes in the orthorhombic space group C2cb with a = 11.923(4) angstrom, b = 20.307(4) angstrom, c = 14.768(4) angstrom, and Z = 4. The refinement was carried out with 1439 observed room temperature reflections to give R(F) = 3.56% and R(w)(F) = 3.51%.