New chelating pyridyl-indenyl and quinolyl-indenyl ligands leading to C1 symmetrical complexes of zirconium via amine elimination. X-ray structure of [3-(2-pyridylmethyl) (indenyl) ]tris(dimethylamido) Zr(IV)

Article abstract of DOI:10.1016/S0022-328X(97)00385-9

Two new chelating (1-) ligands, based on an indenyl group and either a pendant pyridylmethyl arm or a pendant quinolylmethyl arm were synthesized. The two ligands react cleanly with tetrakis(dimethylamido)zirconium by amine elimination reactions leading to complexes of C₁ symmetry. The crystal structure of the pyridyl-indenyl zirconium complex 3 was determined. Compound C₂₁H₃₀N₄Zr (3) crystallizes in the orthorhombic space group Pbca with a = 9.588(1), b = 14.858(12), c = 29.932(7) A, V = 4264.1 (A³), Z = 8. The structure refinement converged to R1 = 0.049 for 2363 F₀ > 4σ(F₀) and wR2 = 0.167 for all 3197 unique data, S = 1.04. The structure shows that the indenyl is bound in a η⁵ fashion blocking the top of the zirconium atom, and the pyridine is coordinated in an exceptionally long 2.536(5) A N-Zr bond, blocking the back of the zirconium atom.