Asymmetric Alkylidene and Oxo Complexes of Tungsten(VI)

Joseph A. Heppert, Steven D. Dietz, Nancy W. Eilerts, Robert W. Henning, Martha D. Morton, Fusao Takusagawa, Frank A. Kaul

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Reactions between (t-BuO)3W(CR) derivatives and 1,1′-bi-2-naphthols (H2R2BINO, R = Me, Br, Ph) generate mononuclear C1-symmetric (R2BINO)(t-BuO)2W(CHR) complexes. An analogous reaction with 2 equiv of H2Me2BINO generates (Me2BINO)2W(CHPh), while a reaction between H2Me2BINO and (t-BuO)4W(O) produces (Me2BINO)(t-BuO)2W(O). This oxo complex was characterized by X-ray crystallography, which shows it to be a highly-distorted trigonal bipyramidal complex in which the Me2BINO ligand adopts a λ chelate stereochemistry. Although the complexes show little stereoselectivity in Wittig-like alkylidene transfer to benzaldehyde, the ring opening metathesis polymerization of norbornene proceeds with modest stereoselectivity. The fraction of cis-polynorbornene increases in concert with the steric demands of the substituents on the R2BINO ligand. Crystal data for (Me2BINO)(t-BuO)2W(O) at 113 K: a = 11.426(3) Å, b = 14.733(3) Å, c = 16.716(4) Å, β = 105.87(2)°, Z = 4, Dcalc. = 1.616, space group P21/n (No. 14), R(F) = 0.053, Rw(F) = 0.106 for 3451 reflections (Fo > 0).

Original languageEnglish
Pages (from-to)2565-2572
Number of pages8
Issue number7
StatePublished - 1993


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