Critical evaluation of the location and refinement of a bridging hydrogen atom in a transition-metal hydride, Mo/sub 2/(eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/(CO)/sub 4/(. mu. -H)(. mu. -P(CH/sub 3/)/sub 2/) by x-ray diffraction
A comparison of the structural parameters obtained by x-ray and neutron diffraction for the transition-metal hydride complex Mo/sub 2/(eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/(CO)/sub 4/(..mu..-H)(..mu..-P(CH/sub 3/)/sub 2/) was performed to examine the discrepancies between the ''x-ray-determined'' and ''neutron-determined'' values for the structural parameters associated with the bridging hydride ligand. Within the experimental limitations of the x-ray analysis, the x-ray-determined hydrogen position reflects the covalent character of the bent Mo--H--Mo bond with the estimated region of maximum overlap displaced ca. 0.2 A from the hydrogen nucleus along the Mo--H--Mo bisector toward the centroid of the Mo--H--Mo triangle. The consequences of this displacement are (1) an apparent shortening of 0.1 A in the average x-ray-determined Mo--H distance of 1.79 (15) A compared to the average neutron-determined Mo--H distance of 1.86 (1) A and (2) a large increase in the Mo--H--Mo bond angle from the neutron-determined value of 122.9 (2)/sup 0/ to the x-ray-determined value of 133 (3)/sup 0/. For closed-type, bent metal--hydrogen--metal bonds, one should then expect to find shorter average M--H bond distances and larger M--H--M bond angles by x-ray diffraction than by neutron diffraction.
- Research Organization:
- West Virginia Univ., Morgantown
- OSTI ID:
- 6795180
- Journal Information:
- Inorg. Chem.; (United States), Vol. 17:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDRIDES
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPLEXES
BOND ANGLE
BOND LENGTHS
COMPARATIVE EVALUATIONS
INTERATOMIC DISTANCES
NEUTRON DIFFRACTION
STEREOCHEMISTRY
X-RAY DIFFRACTION
COHERENT SCATTERING
COMPLEXES
DIFFRACTION
DISTANCE
HYDROGEN COMPOUNDS
SCATTERING
400201* - Chemical & Physicochemical Properties