Pyrrolyl complexes of the early transition metals. 3. Preparation and crystal structure of (η5-C5H5)2Zr(η1-NC4H2Me2)2 and Zr(η1-NC4H2Me2)4

Abstract

The title compounds were synthesized by the reactions of NaNC4H2Me2 with the appropriate complex metal chloride in THF. The crystal structures have been determined from X-ray data measured by counter methods. (η5-C5H5)2Zr(η1-NC4H2Me2)2 crystallizes in the orthorhombic space group Pbca with cell dimensions a = 15.797(6), b = 14.327(5), c = 16.417(6) Å, and ρcalcd = 1.46 g cm−3 for Z = 8. Full-matrix least-squares refinement led to a final R factor of 0.041 based on 536 observed reflections. Zr(η1-NC4H2Me2)4 belongs to the monoclinic space group P21/n with a = 14.065(5), b = 10.717(4), c = 15.733(6) Å, β = 90.61(4)°, and ρcalcd = 1.31 g cm−3 for Z = 4. A final R value of 0.029 resulted from the refinement on the basis of 2649 observed reflections. The dicyclopentadienyl derivative exhibits two features of importance. The Zr—N—centroid angles are 159 and 168°, and the Zr—N bond lengths are 2.24(2) Å. In the homoleptic complex the corresponding values are 164–169° and 2.069(3)–2.090(3) Å. In both cases the bonding parameters are indicative of a substantial amount of π overlap between the zirconium atom and the pyrrolyl nitrogen atom.