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Neutron diffraction studies of tetrahedral cluster transition metal hydride complexes: HFeCO/sub 3/(CO)/sub 9/(P(OCH/sub 3/)/sub 3/)/sub 3/ and H/sub 3/Ni/sub 4/(C/sub 5/H/sub 5/)/sub 4/

Conference ·
OSTI ID:7321308

Structures of the tetrahedral cluster transition metal hydride complexes HFeCo/sub 3/(CO)/sub 9/(P(OCH/sub 3/)/sub 3/)/sub 3/ and H/sub 3/Ni/sub 4/(C/sub 5/H/sub 5/)/sub 4/ have been investigated by low-temperature neutron diffraction techniques. Both complexes have approximate C/sub 3//sub v/ symmetry. In HFeCo/sub 3/(CO)/sub 9/(P(OMe)/sub 3/)/sub 3/ the hydride ligand is found outside the FeCo/sub 3/ cluster, 0.978(3) A from the Co/sub 3/ face, and essentially on the molecular three-fold axis, triply bridging the cobalt atoms. Mean distances in the cluster are Co-Co 2.489(7), Co-Fe 2.559(2), Co-H 1.734(4) A. In H/sub 3/Ni/sub 4/(Cp)/sub 4/ the three hydride ligands are face-bridging, and their mean displacement from the faces of the cluster is 0.90(3) A. The H/sub 3/Ni/sub 4/ core may be envisaged as a distorted cube, with one vertex unoccupied. Mean distances are Ni-Ni 2.469(6), Ni-H 1.691(8), H...H 2.316(6) A. The observed geometries of the two clusters considered here suggest a plausible model for chemisorption of hydrogen on (111) faces of cubic and (001) faces of hexagonal close-packed metals, in which hydrogen atoms are located approximately 1 A above the centers of triangles of metal atoms.

Research Organization:
Brookhaven National Lab., Upton, NY (USA); University of Southern California, Los Angeles (USA). Dept. of Chemistry
DOE Contract Number:
EY-76-C-02-0016
OSTI ID:
7321308
Report Number(s):
BNL-22982; CONF-770510-5
Country of Publication:
United States
Language:
English