Neutron and x-ray diffraction studies of tris(methyldiphenylphosphine)(tetrahydroborato(1-))copper, Cu(P(C/sub 6/H/sub 5/)/sub 2/CH/sub 3/)/sub 3/(BH/sub 4/). The first accurate characterization of an unsupported metal-hydrogen-boron bridge bond
- Brookhaven National Lab., Upton, NY
A single-crystal neutron diffraction study of tris(methyldiphenylphosphine)(tetrahydroborato(1-))copper, Cu-(PPh/sub 2/Me)/sub 3/(BH/sub 4/), has been carried out at low temperature (15 +- 0.5 K) in order to examine the nature of the unidentate attachment of the tetrahydroborate group to the Cu atom. The compound crystallizes in the space group Pna2/sub 1/, Z = 4. Cell constants at 15 K are a = 19.980 (2) A, b = 10.175 (1) A, and c = 17.282 (2) A. The structure was refined on the basis of measured intensities of 4765 reflections, and final discrepancy factors for all reflections are R(F/sup 2/) = 0.043 and R(wF/sup 2/) = 0.047. One H atom of the tetrahydroborate group participates in bonding to the Cu atom with Cu-H = 1.697 (5) A, Cu-B = 2.518 (3) A, and Cu-H-B = 121.7 (4)/sup 0/. There is no evidence for other Cu-H bonding interactions (the second shortest CuH distance is 2.722 (7) A). The H-Cu-P angles (86.2 (2)/sup 0/, 108.5 (2)/sup 0/, 115.3 (2)/sup 0/) are more widely distributed than the B-Cu-P angles (101.4 (6)/sup 0/, 101.7 (7)/sup 0/, 108.8 (7)/sup 0/), and the bridging H atom is significantly displaced off the pseudothreefold axis defined by the CuP/sub 3/ group. This bent, off-center positioning of the bridging H atom is reminiscent of similar observations found in M-H-M bridges and may provide some information about the nature of M-H-B overlap. The tetrahydroborate group is somewhat distorted from tetrahedral symmetry; three of the four B-H distances agree well with one another (1.179 +- 0.005 A), but the fourth (1.330 (6) A) is significantly longer. In addition to the neutron diffraction analysis, structures were determined from room-temperature x-ray data obtained from two other crystals. In general, for nonhydrogen structural parameters there is good agreement among all of the determinations including the original work of Atwood et al.
- OSTI ID:
- 5816034
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:17; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
BORON COMPOUNDS
BORON HYDRIDES
CHEMICAL BONDS
COHERENT SCATTERING
COMPLEXES
COPPER COMPLEXES
CRYSTALS
DATA
DIFFRACTION
DISTANCE
EXPERIMENTAL DATA
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
INTERATOMIC DISTANCES
MONOCRYSTALS
NEUTRON DIFFRACTION
NUMERICAL DATA
PHOSPHINES
PHOSPHORUS COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPLEXES
X-RAY DIFFRACTION