A binuclear alkenyl-bridged zirconium complex catalyzes the chemoselective hydrogenation of 1,3-cyclooctadiene to cyclooctene

Article abstract of DOI:10.1016/0022-328X(90)80100-E

The oligomeric hydrido zirconium complex 2Zr(H)(CH2PPh2)>n (1) reacts with (η⁴-butadiene)zirconocene to yield the (μ-1-η¹ : 1,2-η²-butenyl), (μ-phosphinomethylene) doubly bridged binuclear zirconocene complex 2Zr(μ-CH=CHC2H5)(μ-CH2PPh2)ZrCp₂> 2.Complex 1 reacts with butadiene to give 2 and Ph2PCH3.At 80 deg C complex 2 catalyzes the chemoselective hydrogenation of 1,3-cyclooctadiene to cyclooctene.Formation of a binuclear μ-alkenyl zirconium(IV)/zirconium(II) intermediate, similar to 2, is proposed to explain the effective protection of the remaining C=C double bond in the catalytic cycle.