Degree and Influence of MoS··S Interactions in Oxo−Molybdenum(VI,V,IV) Complexes

Abstract

This paper draws a contrast between the molecular and electronic structures of the oxo−thio−Mo(VI) complex LMoVIOS(S2PPr2-S) and the dithio−oxo−Mo(IV) complex LMoIVO(pyS2-N,S) [pyS2 = pyridyl-2-dithio; L = hydrotris(3,5-dimethylpyrazol-1-yl)borate] and reports the generation of Mo(V) species by the reduction or oxidation of these (formally) Mo(VI) and Mo(IV) complexesa spectacular demonstration of the redox versatility of Mo−S centers.

Redox Interplay of Oxo−Thio−Tungsten Centers with Sulfur-Donor Co-Ligands

“…The ν(WdE) modes are typical of other oxo-thio-W(VI) complexes (vide supra); [10][11][12]25 in contrast, the ν(ModO) band of Tp*MoO(pyS 2 ) is observed at 960 cm -1 . 7 The 1 H NMR spectrum confirmed molecular C 1 symmetry with pyrazolyl methyl resonances in the range δ 2.3-3.0, characteristic of related Tp*WOSX complexes. The spectrum was devoid of the shielded resonance at ca.…”

“…The potential for M/S redox interplay in these systems is underscored by often unpredictable outcomes, including multisite redox changes and facile ligand transformations, in "simple" reactions involving metal thio-(late) complexes; 2-5 induced internal redox reactions are among the most striking and well-defined reactions of this type. 6 In previous work, 7 we compared the molecular and electronic structures of the complexes Tp*Mo VI OS(S 2 PPr i 2 -S) 8 and Tp*Mo IV O(pyS 2 -N,S) (Tp* ) hydrotris(3,5-dimethylpyrazol-1-yl)borate, pyS 2 ) pyridine-2-dithio). The spectroscopic and structural properties of these complexes, particularly the observed Mo-S(1) and S(1)-S(2) distances ( Figure 1), were consistent with oxo-thio-Mo(VI) and (dithio)oxo-Mo(IV) formulations, respectively.…”

Facets of early transition metal–sulfur chemistry: Metal–sulfur ligand redox, induced internal electron transfer, and the reactions of metal–sulfur complexes with alkynes

“…The bis(sulfido)-W(VI) complexes react with alkynes to produce dithiolene ligand complexes (Section 4. (pyS 2 = pyridyl-2-dithio) [46]. The Mo(IV) formulation is supported by the spectroscopic and structural properties of the complex.…”

“…Once again, internal redox leading to the reduction of W(VI) and oxidation of sulfide ligands to disulfide is prevented by the more negative reduction potential of W(VI) vs Mo(VI). Investigations of the redox behavior of Tp * MoOS-(S 2 PR 2 ) and Tp * MoO(pyS 2 ) revealed that the complexes were both oxidized and reduced to Mo(V) metal-based d 1 radicals, as shown in Chart 1 [39,46]. Similarly, the W(VI) complexes, Tp * WOS(S 2 PR 2 ) and Tp * WOS(pyS), were cleanly reduced to oxosulfido-W(V) species and oxidized to oxo(disulfido)-W(V) complexes via internal redox; these redox changes are summarized in Chart 2.…”

Scorpionate Complexes as Models for Molybdenum Enzymes

“…In reactions that underscore the often counter‐intuitive redox interplay of Mo/W and S,, these and related pyridinethiol‐based complexes yield EPR‐active M V complexes upon reduction and oxidation. Details of these reactions can be found elsewhere , , . Ligand based redox reactions are a feature of Mo/S chemistry, and some are postulated to be involved in the catalytic cycle of certain Mo enzymes , …”