ENANTIOSELECTIVE CATALYSIS .78. OPTICALLY-ACTIVE PHOSPHIDO-BRIDGED IRON COMPLEX [(ETA-5-C5H5)2FE2(MU-H)(MU-PMEN2)(CO)2] - SYNTHESIS, ISOMERIZATION, CATALYSIS

The hydrido-phosphido-bridged complex [(eta(5)-C5H5)2Fe2(mu-H)(mu-PMen2)(CO)2] (3) is prepared from [(eta(5)-C5H5)Fe(CO)2]2 (1) and dimenthyphosphine HPMen2 in boiling toluene. The reaction proceeds via the intermediate [(eta(5)-C5H5)2Fe2(HPMen2)(CO)3] (2). 2 forms a pair of cis-trans isomers, whereas 3 consists of three isomers, the meso-isomer cis-3 and the two diastereomers trans-3a and trans-3b. In hot toluene, 2 gives 1 and 3. In solution, 3 undergoes a photochemical cis-trans isomerization reaction. 3 is an enantioselective catalyst in the photochemical hydrosilylation of acetophenone with diphenylsilane to give 1-phenylethanol in up to 33% ee.