Metrical characterization of tridentate tetrahydroborate ligation to a transition-metal ion. Structure and bonding in Hf(BH/sub 4/)/sub 4/ by single-crystal neutron diffraction
- Argonne National Lab., IL
This paper reports the molecular structure of the transition-metal tetrahydroborate complex Hf(BH/sub 4/)/sub 4/ by single-crystal neutron diffraction at 110 K. The compound crystallizes in the cubic space group P43m (T/sub d//sup 1/, No. 215) with a unit cell of dimensions a = 5.827 (4) angstrom. Full-matrix least-squares refinement gave a final value of R(F/sub 0//sup 2/) = 0.103 for 71 unique reflections with F/sub 0//sup 2/ > sigma(F/sub 0//sup 2/). The molecular structure consists of monomeric Hf(BH/sub 4/)/sub 4/ units having rigorously T/sub d/ symmetry and tridentate tetrahydroborate coordination. Important bond distances are Hf-B = 2.281 (8) angstrom, Hf-H(bridging) = 2.130 (9) angstrom, B-H(bridging) = 1.235 (10) angstrom, and B-H(terminal) = 1.150 (19) angstrom. Important bond angles are Hf-H(bridging)-B = 80.6 (6)/sup 0/, H(bridging)-B-H(bridging) = 105.8 (6)/sup 0/, and H(bridging)-B-H(terminal) = 112.9 (10)/sup 0/. It is seen that the internal BH/sub 4//sup -/ metrical parameters do not differ significantly from those in Hf(CH/sub 3/C/sub 5/H/sub 4/)/sub 2/(BH/sub 4/)/sub 2/, in which the tetrahydroborate ligands are coordinated in an unsymmetrical bidentate fashion. However, Hf-B is 0.17 (1) angstrom longer and Hf-H(bridging, average) 0.035 (9) angstrom shorter in the latter molecule.
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 5438666
- Journal Information:
- Inorg. Chem.; (United States), Vol. 22:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BORATES
STRUCTURAL CHEMICAL ANALYSIS
BOND ANGLE
BOND LENGTHS
CHEMICAL BONDS
LIGANDS
LOW TEMPERATURE
MONOMERS
NEUTRON DIFFRACTION
BORON COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
DIMENSIONS
LENGTH
OXYGEN COMPOUNDS
SCATTERING
400201* - Chemical & Physicochemical Properties