ISSN:
1432-1327
Keywords:
Key words Oxomolybdenum complexes
;
Molybdoenzymes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The complexes LMoVIO2X [L = hydrotris(3,5-dimethylpyrazol-1-yl)borate; X = Cl, Br, NCS, OPh, SPh, SCH2Ph] are converted to air-stable complexes LMoVO(OSiMe3)X by one-electron coupled electron-electrophile transfer (CEET) reactions involving cobaltocene and the electrophilic reagent Me3SiCl. These complexes may also be obtained from LMoVO(OH)X by reaction with Me3SiCl in the presence of base. LMoVO(OSiMe3)(SCH2Ph) crystallises in space group P21/n, with a = 8.526 (1) Å, b = 23.141 (3) Å, c = 16.499 (2) Å, β = 103.75 (12)° and Z = 4. The complex exhibits a distorted octahedral structure with a facially tridentate L ligand and mutually cis oxo [Mo=O = 1.675 (4) Å], silyloxo [Mo–O = 1.932 (4) Å] and thiolato [Mo–S = 2.398 (2) Å] ligands. The detailed redox properties of LMoVO(OR)X (R = SiMe3, alkyl, aryl) differ from those of LMoVO(OH)X. Centres [MoVO(OR)] are candidates for the stable "inhibited" forms of certain molybdenum enzymes formed under conditions which apparently disfavour the catalytically active [MoVO(OH)] centres. In the coordinating solvent pyridine (py), both LMoVIO2(SPh) and LMoVO(OSiMe3)(SPh) are reduced in one-electron steps to stable LMoIVO(py)(SPh). LMoIVO(py)(SR) complexes are also obtained from LMoVIO2(SR) (R = Ph, CH2Ph, CHMe2) via a two-electron oxygen atom transfer reaction with tertiary phosphines in pyridine. Consequently, the Mo(IV) product is accessible via a concerted two-electron step or via two one-electron steps.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050073
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