Sulfur bridged complexes

Electron transfers may lead to modifications of the metal-sulfur core of binu-clear sulfur-bridged complexes. The CV of [M2S2(cp )2(/r-S)2] 11 (M = Mo or W, cp = -C5H5 Me ) [30] showed that the first reduction was a one-electron process. 

The reductions of the sulfur-bridged complexes 39 and 40 (L = CO) are reversible, giving monoanions stable on the time scale of cyclic voltammetry. In the presence of P(OMe)a, electrocatalytic carbonyl substitution occurs since E° for the substitution product is more negative than that of the carbonyl precursor. Thus, for example, 40 (L = CO) gave 88% yield of 40 [L = P(OMe)3] when only 0.05 of charge was passed (55). 

Fe3(CO)[2 reacts with o-aminobenzenethiol in boiling cyclohexane to form the nitrogen- and sulfur-bridged complex (XII), through loss of hydrogen from both the sulfur and nitrogen atoms (338). 

The crystal structure of the sulfur-bridged complex [Fe(jy -C5H4S)2]Rh( y -C5Me5)-(PMe3) is illustrated in Fig. 7-41 [135]. 

The sulfur bridged complexes described here are stable to aerobic oxidation, in contrast to di-/t-oxo complexes. ... 

From [FeCp(CO)2] and CH3SSCH3 a sulfur-bridged complex (XXX)... 

The reaction of mercaptans with cobalt carbonyl has long been known to give sulfur-bridged complexes of the type [CoSR(CO)3]2, with R = C2H5, CjHs 233). The compound [Co(SC2H5)(CO)3]2 reacts further with o-phenanthroline to give monomeric [Co(SC2Hs)(CO)2(o-phen)] 233). 

In the same year, Evans and coworkers reported the electrochemical reduction of protons to H2 catalyzed by the sulfur-bridged dinuclear iron complex 25 as a hydrogenase mimic in which acetic acid was used as a proton source [201]. The proposed mechanism for this reaction is shown in Scheme 60. The reduction of 25 readily affords 25 via a one electron reduction product 25. Protonation... 

Picolylphenylketone S-benzyldithiocarbazate, 48, yielded paramagnetic [ Ni(48-H)A 2] (A = Cl, Br) and diamagnetic [Ni(48-H)I] [207]. All three compounds are non-electrolytes and the iodo complex is planar while the other two complexes involve sulfur bridging atoms and five-coordinate nickel(II) centers. All three complexes can be converted to monomeric, octahedral complexes by addition of pyridine, 2-picoline or quinoline. 

Figure 49 Cyclic sulfur-bridged octanuclear complexes [M2 Pd[Co(aet)3]2 2] ...

Rhenium(III) complexes with sulfur dioxide ligands have been obtained by oxidation of dimeric sulfido-bridged complexes either by air or by NO(PFe). The oxidation of the bridging sulfur atoms is facilitated by the high electron density at these ligands. 

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