MOLECULAR PRECURSORS OF BISMUTH OXIDES - BETA-DIKETONATES AND ALKOXIDES - MOLECULAR-STRUCTURE OF [BI2(MU-2,ETA-1-OC2H4OME)4(ETA-1-OC2H4OME)2]INFINITY AND OF BI(OSIPH3)3(THF)3

Various routes to bismuth(III) alkoxides and beta-diketonate derivatives have been investigated. Metathesis reactions of the halides and the appropriate sodium derivative offered [Bi(O(t)Bu)3]infinity (1), [Bi(OC2H4OMe)6]infinity (2), [Bi(OSiPh3)3]m and Bi(dpm)3 (dpmH = dipivaloylmethane) in good yields. The alkoxides display different physical properties; 1 has good volatility, while 2 is highly soluble. Complex 2 and Bi(OSiPh3)3(THF)3 (3) have been characterized by X-ray diffraction. Compound 2 shows a one-dimensional extended ''skew'' chain structure based on dimeric asymmetric Bi(mu-2,eta-1-OC2H4 OMe)4(OC2H4OMe)2 units. The alkoxo functionality leads to a distorted pyramidal tetragonal surrounding, but the ether functionality of the bridging groups provides further oxygen donors, and thus coordination numbers of seven and even eight are reached. Bi(OSiPh3)3(THF)3 is monomeric with a capped octahedron geometry around the metal. The thermal stability of the volatile precursors 1 and Bi(dpm)3 is in a favour of the alkoxide, while the high solubility of 2 is attractive for sol-gel purposes.