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

In this study, the addition of boranes to ( E )-(η 5 -C 5 H 5 ) 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 )-(η 5 -C 5 H 5 ) 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 -(η 5 -C 5 H 5 ) 2 Zr(CH(Bpin)CH 2 Ph)Cl (pin = 1, 2-O 2 C 2 Me 4 ) (2) . Crystals of 2 were orthorhombic with a = 18.545(3) Å, b = 15.713(3) Å, c = 16.157(3) Å in the space group Pccn . An x-ray diffraction study has also been conducted on the trinuclear zirconium oxide species (η 5 -C 5 H 5 ) 2 ZrO 2 [ZrCl(η 5 -C 5 H 5 ) 2 ] 2 (4) . Crystals of 4 were orthorhombic with a = 13.6000(8) Å, b = 14.2252(8) Å, c = 17.6500(10) Å in the space group P2(1)2(1)2(1) .