431887-64-8Relevant articles and documents
An yttrium-based system to evaluate Lewis base coordination to an lectropositive metal in a metallocene environment
Evans, William J.,Fujimoto, Cy H.,Johnston, Matthew A.,Ziller, Joseph W.
, p. 1825 - 1831 (2002)
The unsolvated bimetallic yttrium complex (C5Me5)2Y(μ-Cl)Y(C5Me5 )2Cl (1) provides a convenient platform upon which to compare the coordination chemistry of oxygen-donor ligands and monomers with Lewis acidic metal ions. Reaction of 1 with 2 equiv of oxygen-containing substrates formed the monomeric complexes (C5Me5)2YCl(L) (L = THF (2), benzophenone (3), methyl methacrylate (4), ε-caprolactone (5), hexamethylphosphoramide (6), ε-caprolactam (7), 1-methyl-2-pyrrolidinone (8), N,N′-dimethylpropyleneurea (9)). Each of these readily crystallize, which allows comparison of the Y-O interaction in the solid state. The X-ray data show that the numerical values of the measured Y-O lengths decrease in the order THF > benzophenone > methyl methacrylate > ε-caprolactone > hexamethyl-phosphoramide > ε-caprolactam > 1-methyl-2-pyrrolidinone > N,N′-dimethylpropyleneurea, although these bond lengths span only a short range and some are the same within experimental error. In the case of e-caprolactam, a bis adduct, (C5Me5)2YCl(ε-caprolactam)2 (10), can be isolated from the reaction of 1 and excess ε-caprolactam. 1H NMR spectroscopy indicates that (C5Me5)2YCl(L)L′ ligand displacement reactions in solution with 2-9 follow a trend consistent with the bond lengths except for (C5Me5)2YCl(ε-caprolactam) (7), in which L participates in hydrogen bonding to the chloride.
