Molybdenum binding site models for the molybdenum cofactor. Synthesis, spectroscopic characterization, and EHMO analysis of (NBu[sup n][sub 4])Na[Mo(O[sub 2]CC(S)Ph[sub 2])[sub 3]]
- Universitat de Valencia (Spain)
The reaction of the cis-dioxo Mo(VI) complex [MoO[sub 2](O[sub 2]CC(S)Ph[sub 2])[sub 2]][sup 2[minus]] (1), having two coordinated thiobenzilate ligands, with an excess of thiobenzilic acid yields the monomeric monooxo Mo(V) complex [MoO(O[sub 2]CC(S)Ph[sub 2])[sub 2]][sup [minus]] (2), which is stable under these acidic conditions. However, partial neutralization of the thiobenzilic acid results in the reduction of 2, which, once formed, slowly yields the non-oxo tris-chelate Mo(IV) species [Mo(O[sub 2]CC(S)Ph[sub 2])[sub 3]][sup 2[minus]] (3). The generation of such a monomeric Mo(V) intermediate mimics the redox behavior of molybdenum hydroxylase enzymes. The pH dependence of the above Mo(V)-Mo(IV) conversion reaction as well as its relationship to the molybdenum center in nitrate reductase is discussed. The Mo site in 3 was revealed to be trigonal prismatic by a previous X-ray structure study. This structure constitutes the first example of a trigonal-prismatic geometry in a Mo(IV) complex whose ligands have no extensive intraligand [pi]-conjugation. The electronic structure as well as the spectroscopic and electrochemical properties are analyzed in terms of extended Hueckel molecular orbital calculations which are consistent with previous molecular orbital calculations for tris(dithiolene) complexes. Compared to the case of the dithiolene complexes, a stabilization of the prismatic structure is observed in the present thiobenzilate complex (3) as a result of improved [sigma]- and [pi]-bonding interactions between the Mo(IV) center and the sulfurs of the thiobenzilate ligands. The role of the solid packing interactions is also considered. 33 refs., 5 figs.
- OSTI ID:
- 6234788
- Journal Information:
- Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 32:10; ISSN 0020-1669; ISSN INOCAJ
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
BONDING
CALCULATION METHODS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPLEXES
ELECTRONIC STRUCTURE
ENZYMES
FABRICATION
JOINING
MATHEMATICAL MODELS
MOLECULAR ORBITAL METHOD
MOLECULAR STRUCTURE
MOLYBDENUM COMPLEXES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PH VALUE
PROTEINS
REDUCTION
STABILIZATION
SYNTHESIS
TRANSITION ELEMENT COMPLEXES