CHEMISTRY OF LOW-VALENT ZIRCONIUM COMPLEXES WITH TERTIARY PHOSPHINES - REVERSIBLE CO BINDING BY BIS(ETA-BUTADIENE)[1,2-BIS(DIMETHYLPHOSPHINO)ETHANE]ZIRCONIUM

Treatment of ZrCl4 with l, 2-bis(dimethylphosphino)ethane (dmpe) affords ZrCl4(dmpe)2. Reduction of ZrCl4(dmpe)2 with Na/Hg in the presence of butadiene yields the dmpe-bridged dimer [Zr(η-C4H6)2(dmpe)]2(dmpe), which is in equilibrium with coordinatively unsaturated Zr(η-C4H6)2(dmpe) and free dmpe. Treatment of [Zr(η-C4H6)2(dmpe)]2(dmpe) with CO at low temperatures gives thermally unstable Zr(η-C4H6)2(dmpe)(CO), which decomposes under vacuum to Zr(η-C4H6)2(dmpe). This complex forms adducts with a variety of small Lewis bases. Equilibrium constants for adduct formation have been measured by NMR techniques; trends in AH for adduct formation suggest that Zr(η-C4H6)2(dmpe) prefers small, (σ-donating ligands. [Zr(η-C4H6)2(dmpe)]2(dmpe) is a hydrogenation catalyst. © 1979, American Chemical Society. All rights reserved.