Synthesis and X-ray and Neutron Structures of Zr{(μ-H)₂BC₈H₁₄}₄

The complex Zr(9-BBN)4 [9-BBN = (μ-H)2BC8H14] has been synthesized via the reaction of K(9-BBN) with ZrCl4 in diethyl ether. The structure of the title compound has been determined by X-ray and neutron single-crystal diffraction techniques. Each 9-BBN ligand is coordinated to the Zr atom via two B−H−Zr bridges, and these metal−ligand bonding interactions are further augmented by three prominent C−H···Zr agostic interactions. Average molecular parameters derived from the neutron analysis: Zr−H = 2.051(8) Å, B−H = 1.286(7) Å, Zr···B = 2.409(6) Å, Zr−H−B = 87.7(4)°, H−Zr−H = 58.9(3)°. The Zr···H distances corresponding to the three C−H···Zr agostic interactions are 2.424(7), 2.663(8), and 2.551(7) Å. The fourth potential C−H···Zr interaction has a Zr···H distance [3.146(7) Å] that is too long to be considered in the agostic range. Single-crystal X-ray diffraction data were collected on an Enraf-Nonius Kappa CCD diffraction system, and neutron diffraction data were collected on the quasi-Laue diffractometer VIVALDI at the Institut Laue-Langevin; the final agreement factor for the neutron analysis is 6.52% for 2557 reflections with I > 2σ(I).