Hydroboration of some organometallic systems.

This thesis contains a review of the literature concerning the hydroboration of multiple bonded organic molecules and the synthetic utility of the organoboranes so formed in these reactions.Although the reactions of diborane with unsaturated organic molecules are well known, there is little information referring to such reactions with organometallic complexes containing unsaturated ligands. Details are presented herein of complexes which have been synthesized to enable investigation of their reactions with diborane and the results of such subsequent reactions. Hydroboration of systems which have been studied include those which contain either sigma or pi-interactions between the organic moiety and a metal. 2,4-Pentanedione and related compounds undergo hydroboration and for the former case, reduction of the two carbonyl groups occurs essentially simultaneously giving after hydrolysis a dimeric borate ester of a meso-diol. In contrast the ester produced from the reaction of boric acid and the diol formed from the reduction of the dione with sodium borohydride is a mixture of racemic and meso-forms. In metal 2,4-pentanedionates, where the multiple bonds are delocalised, identifiable products from hydroboration were not obtained. For other systems having localised or delocalised groups pi-bonded to a metal, for example (n-C[5]-H[5])[2]fe or (PhC=CPh)Pt(Ph[3]P)[2], hydroboration could not be obtained.In substituted ferrocene derivatives having multiple bonded groups attached to the organic ring system, for example acetylferrocene and vinylferrocene, only hydroboration of the side chain occurred with the mode of addition being essentially the same as if the metal had not been present. Although indene, (C[9]H[7]), underwent hydroboration of the 5-membered ring producing 2-indanol on oxidation, when the indene moiety was pi-bonded to iron, the 6-membered ring underwent hydroboration.