Addition of boranes to (E)-(η5-C5H5)2Zr(CH=CHPh)Cl

In this study, the addition of boranes to (E)-(eta(5)-C5H5)(2)Zr(CH=CHPh)Cl (3) has been examined in order to investigate the regioselectivity of these 'hydroboration' reactions. We have found that these additions proceed with remarkable selectivity to give exclusive formation of a saturated organic molecule where one carbon atom has both the boron and the zirconium fragments. These reactions do not proceed via a conventional hydroboration reaction, but instead go through an initial transmetalation step to generate (E)-(eta(5)-C5H5)(2)Zr(H)Cl (1) and the corresponding alkenyl boron intermediate, whereupon subsequent hydrozirconation of this latter species gives the geminal products. An x-ray diffraction study has been conducted on gem-(eta(5)-C5H5)(2)Zr(CH(Bpin)CH2Ph)Cl (pin = 1, 2-O2C2Me4) (2). Crystals of 2 were orthorhombic with a = 18.545(3) , b = 15.713(3) , c = 16.157(3) in the space group Pccn. An x-ray diffraction study has also been conducted on the trinuclear zirconium oxide species (eta(5)-C5H5)(2)ZrO2[ZrCl(eta(5)-C5H5)(2)](2) (4). Crystals of 4 were orthorhombic with a = 13.6000(8) , b = 14.2252(8) , c = 17.6500(10) in the space group P2(1)2(1)2(1).