Structural comparison of oxobis(benzene-1,2-dithiolato)molybdenum-(V) and -(IV) complexes

Abstract

The [M0O(bdt)~]-/[MoO(bdt)~]2-(H2bdt = benzene-I ,2-dithiol) redox couple, in dimethylformamide solution, is a fully reversible process at €+ = -350 mV vs. standard calomel electrode and each of these anions has been characterised by X-ray crystallo raphy; the metal-ligand bond lengths of the former are slightly shorter than those of the latter, MoV-0 = 1.668(3) 1, MolV-0 = 1.699(6) A, mean MoV-S = 2.377(1) A, MolV-S = 2.388(2) A.

A mononuclear molybdenum(V) mono-oxo biphenyl-2,2′-dithiolate complex in which the metal resides within a cleft formed by the ligands and that exhibits N-H...S hydrogen bonding in the solid state

“…The Mo-oxo distance in 1 [1.684(8) ] is identical within error to other Mo V (O)S 4 complexes [39,40,41,42,43,44,45,46,47] and is typical for a terminal Mo=O [71]. Essentially the same metal-oxygen distances (1.6±1.8 ) have been found for the Mo(IV) and Mo(VI) oxo-containing enzyme sites by X-ray crystallography [18,21,22,23,24,25] and X-ray absorption spectroscopy [72,73,74 190.59 (13) The Mo ion in 1 sits 0.703 out of the S 4 basal plane, which is on the low end of those reported for other Mo V (O)S 4 structures (0.687±0.82 ) [39,41,42,43,44,45,46,47], as well as when compared to the crystallographically characterized Mo(IV) and Mo(VI) enzyme sites with two dithiolene groups (0.4±1.7 ) [20,21,23,24,26].…”

“…Although this band occurs near the lower end of the 920±1050 cm ±1 range seen for Mo=O complexes [67], it is typical for Mo V (O)S 4 complexes, which absorb from 910 to 950 cm ±1 [42,43,44,45,46,47,56,57,58,59,60,61]. Resonance Raman (RR) data for this region of the relevant enzymes' Mo(V) states have not been reported, presumably owing to the difficulty in generating a Mo(V) enzyme free of significant Mo(IV) and Mo(VI) impurities.…”

“…Nearly all of the handful of crystallographically characterized Mo V (O)S 4 complexes [39,40,41,42,43,44,45,46,47] have ligands that direct their steric bulk primarily away from the metal center. Here we report the synthesis and characterization of a unique Mo(V) complex, with dithiolate ligands that incorporate a biphenyl framework which also provides some steric protection that may inhibit the undesirable dimer formation.…”

Structures of tetraphenylphosphonium bis(ethane-1,2-dithiolato)oxorhenium(V) and tetraphenylphosphonium bis(benzene-1,2-dithiolato)oxorhenium(V)

“…The two Re complexes are isostructural with their Mo analogues Boyde et al, 1986), and can thus be used as diamagnetic hosts for single-crystal ESR studies of the paramagnetic Mo complexes.…”

Molybdenum and Tungsten Oxidoreductase Models

“…[6] The Garner group published the very first crystallographically characterised model for the DMSOR family with a rather simple dithiolene ligand (Figure 2a), [7] which is now known to be a quite good model of arsenite oxidase [8] but a less good model for the typical DMSOR active site. Their main focus, however, in cooperation with the organic chemistry group of Joule, was the development of a variety of ligand systems that mimicked different aspects of molybdopterin.…”