Heterometal cuboidal clusters MFe[sub 4]S[sub 6](PEt[sub 3])[sub 4]Cl (M = V, Mo): synthesis, structural analysis by crystallography and EXAFS, and relevance to the core structure of the iron-molybdenum cofactor of nitrogenase

Journal Article · Wed Jun 30 00:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00066a024· OSTI ID:5813923

Nordlander, E; Lee, S C; Cen, W; Holm, R H ^[1]; Wu, Z Y; Natoli, C R ^[2]; Di Cicco, A ^[3]; Filipponi, A ^[4]; Hedman, B; Hodgson, K O ^[5]

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1. Harvard Univ., Cambridge, MA (United States)
2. INFN, Frascati (Italy)
3. Universita degli Studi di Camerino (Italy)
4. Universita degli Studi dell'Aquila, Coppito-L'Aquila (Italy)
5. Stanford Univ., CA (United States)

The cluster self-assembly system MCl[sub 3](THF)[sub 3]/2FeCl[sub 2](PEt[sub 3])[sub 2]4-7(Me[sub 3]Si)[sub 2]S affords, after separation of cluster coproducts, the isomorphous compounds MFe[sub 2]S[sub 6](PEt[sub 3])[sub 4]Cl (M = V, Mo) in modest yields. These species were identified by spectroscopic methods and X-ray diffraction. The compounds crystallize in trigonal space group R3; the cluster molecules are isostructural and essentially isometric. They consist of a cuboidal Fe[sub 4]S[sub 3] fragment that is bridged by three [mu][sub 2]-S atoms to a M-PEt[sub 3] unit whose M-P bond is coincident with an imposed C[sub 3] axis. Coordination is completed at the three symmetry-related Fe sites by PEt[sub 3] ligands and at the Fe site on the C[sub 3] axis by chloride. The trigonal pyramidal coordination units FeS[sub 3]P and MoS[sub 3]P are infrequently observed and unprecedented, respectively, and the cuboidal fragment has been observed previously only in several Fe-S-nitrosyl clusters. The cluster structure presents atoms at a series of distances from the M or Fe atoms and has been utilized in a detailed test of distance determinations in a new approach to the analysis of EXAFS data using theoretical phases and amplitudes (the GNXAS approach). The Mo and Fe EXAFS of the cluster MoFe[sub 4]S[sub 6](PEt[sub 3])[sub 4]Cl have been analyzed in detail and first coordination shell distances determined with high accuracy. The contribution of multiple scattering pathways in the EXAFS of the cluster has been evaluated. The relevance of the results to the FeMo-cofactor structure as recently deduced from protein crystallography is considered. 57 refs., 10 figs., 5 tabs.

• OSTI ID: 5813923
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 115:13; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON COMPLEXES
SYNTHESIS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
MOLYBDENUM COMPLEXES
VANADIUM COMPLEXES
CRYSTALLOGRAPHY
EXPERIMENTAL DATA
LIGANDS
MASS SPECTROSCOPY
NITROGENASE
NUCLEAR MAGNETIC RESONANCE
TOPOLOGY
COHERENT SCATTERING
COMPLEXES
DATA
DIFFRACTION
ENZYMES
INFORMATION
MAGNETIC RESONANCE
MATHEMATICS
NITRO-GROUP DEHYDROGENASES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROTEINS
RESONANCE
SCATTERING
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
550200* - Biochemistry
400201 - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures