High-nuclearity close-packed palladium-nickel carbonyl phosphine clusters : hesteropalladium [Pd{sub 16}Ni{sub 4}(CO){sub 22}(PPh{sub 3}){sub 4]{sup 2-} and [Pd{sub 33}Ni{sub 9}(CO){sub 41}(PPh{sub 3}){sub 6}]{sup 4-} containing Pseudo-T{sub d} ccp Pd{sub 16}Ni{sub 4} and Pseudo-D{sub 3h} hcp Pd{sub 33}Ni{sub 9} cores.
[Pd{sub 16}Ni{sub 4}(CO){sub 22}(PPh{sub 3}){sub 4}]{sup 2-} (1) and [Pd{sub 33}Ni{sub 9}(CO){sub 41}(PPh{sub 3}){sub 6}]{sup 4-} (2) were obtained as the two major products from the reduction of PdCl{sub 2}(PPh{sub 3}){sub 2} with [Ni{sub 6}(CO){sub 12}]{sup 2-}. Their crystal structures as [PPh{sub 4}]{sup +} salts were unambiguously determined from CCD X-ray crystallographic analyses; the resulting stoichiometries were ascertained from elemental analyses. Infrared, multinuclear {sup 1}H, {sup 31}P{l_brace}{sup 1}H{r_brace} NMR, UVvis, CV, variable-temperature magnetic susceptibility, and ESI FT/ICR mass spectrometric measurements were performed. The Pd{sub 16}Ni{sub 4} core of 1 ideally conforms to a ccp {nu}{sub 3} tetrahedron of pseudo-T{sub d} ({sub {ovr 4}}3m) symmetry. Its geometry normal to each tetrahedral Pd7Ni3 face (i.e., along each of the four 3-fold axes) may be viewed as a four-layer stacking of 20 metal atoms in a ccp [a(Ni{sub 1}) b(Pd{sub 3}) c(Pd{sub 6}) a(Pd{sub 7}Ni{sub 3})] sequence. A comparative analysis of the different ligand connectivities about the analogous metal-core geometries in 1 and the previously reported [Os{sub 20}(CO){sub 40}]{sup 2-} has stereochemical implications pertaining to the different possible modes of carbon monoxide attachment to ccp metal(111) surfaces. The unique geometry of the Pd{sub 33}Ni{sub 9} core of 2, which has pseudo-D{sub 3h} ({sub {ovr 6}}2m) symmetry, consists of five equilateral triangular layers that are stacked in a hcp [a(Pd{sub 7}Ni{sub 3}) b(Pd{sub 6}) a(Pd{sub 7}Ni{sub 3}) b(Pd{sub 6}) a(Pd{sub 7}Ni{sub 3})] sequence. Variable-temperature magnetic susceptibility measurements indicated both 1 and 2 to be diamagnetic over the entire temperature range from 5.0 to 300 K. Neutral Pd{sub 12}(CO){sub 12}(PPh{sub 3}){sub 6} (3) and [Pd{sub 29}(CO){sub 28}(PPh{sub 3}){sub 7}]{sup 2-} (4) as the [PPh{sub 4}]{sup +} salt were obtained as minor decomposition products from protonation reactions of 1 and 2, respectively, with acetic acid. Compound 3 of pseudo-D{sub 3d} ({sub {ovr 3}}2/m) symmetry represents the second highly deformed hexacapped octahedral member of the previously established homopalladium family of clusters containing uncapped, monocapped, bicapped, and tetracapped Pd6 octahedra. The unprecedented centered 28-atom polyhedron for the Pd{sub 29} core of 4 of pseudo-C{sub 3v} (3m) symmetry may be described as a four-layer stacking of 29 metal atoms in a mixed hcp/ccp [a(Pd{sub 1}) b(Pd{sub 3}) a(Pd{sub 10}) c(Pd{sub 15})] sequence.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 943053
- Report Number(s):
- ANL/CHM/JA-37088; INOCAJ; TRN: US201002%%533
- Journal Information:
- Inorg. Chem., Vol. 40, Issue 11 ; May 21, 2001; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- ENGLISH
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