Synthesis and crystal structure of a zirconium(III) diacetylide tweezer complex:: [(η5-C5HMe4)2Zr(η1-CCSiMe3)2]K+

The zirconocene diacetylide (eta(5)-C5HMe4)(2)Zr(eta(1)-C drop CSiMe3)(2) (1) is reduced by potassium in toluene to give the paramagnetic tweezer complex [(eta(5)-C5HMe4)(2)Zr(eta(1)-C drop CSiMe3)(2)]K--(+) (2). The presence of Zr(III) follows from the ESR spectrum of 2 (g = 1.9914, a(Zr) = 1.86 mT). The X-ray crystal structures show that the bite angle of tweezer arms of 102.7 degrees in 1 is diminished to 92.8 degrees in complex 2. The potassium cation is embedded between the acetylide arms, 1.13 Angstrom away from the bite angle plane, at the Zr-K distance of 3.818(1)Angstrom. (C) 1998 Elsevier Science S.A.