Sulfur bridged dimer

Oxidation of the Mo 2 fragment is also induced by reacting Mo2(02CCH3)4 with [NR,] [J CN H.,)2] as is discussed in Section III.D.2. Oxidative addition across one of the dithiocarbamate C-S linkages leads to an oxidation state of 4+ for the molybdenum atoms in the resultant sulfur-bridged dimer (216, 217). 

The dimers [Ni(TFD)(L)J2 (L = R2Dtc" or RXant ) can be reduced chemically by o-phenylene diamine to give yellow solutions of the dianions. The crystal structure of the [Ni(TFD)(Et2Dtc)] 2 complex was determined (320). It consists of well-separated centrosymmetric sulfur-bridged dimers (Table XXII). The nickel ion has a square pyramidal coordination and lies 0.36 A out of the equatorial plane in the direction of the apical bridge sulfur. The structure resembles that of the dimeric Cu(R2Dtc)2 complexes. 

The complexes [ Ni( -SR)Cp 2] (57), [ Ni(/i-PPh2)Cp 2] (58), and [ Ni(CO)2(/x-PPh2) 2] (59) are reduced to persistent anion radicals, and the carbonyl also forms a dianion (53). The sulfur-bridged dimers 57 (R = alkyl or aryl) are also easily oxidized (E° 0.0 V) and the monocations, although not isolable, were characterized by ESR spectroscopy (53, 61). Second, reversible oxidation waves at about 0.8 V were also observed for 57 (67). 

The sulfur-bridged dimer [( -SCH3)Fe(CO)2L]2 does, however, undergo insertion of SO2 into the Fe-Fe bond for L = PMe3 and P(CH3)2Ph. 

The sulfur-bridged dimer Cl3W(/i-THT)3WCl3 undergoes C-S bond cleavage upon attack... 

Reactions of stannylenes Sn[N(SiMe3)2][(NCy)2CR] (R=Me, t-Bu) stabi-hzed by bulky trialkyl amidinates with elemental sulfur proceeded efficiently to afford the corresponding tetrathiastannolane Sn[N(SiMe3)2][(NCy)2CR]S4 [23]. This is in sharp contrast to the reaction of M[N(SiMe3)2]2 (M=Ge, Sn) with elemental sulfur giving the bridged dimer [M N(SiMe3)2 2S]2 [24, 25] (Scheme 2). 

Molybdenum(V) chemistry is dominated by oxo complexes many of these exist as dimers, but monomeric species can be isolated from strongly addic solutions or under nonaqueous conditions. Non-oxo compounds are also known, both as monomers and as dimers or polymers with halide or sulfur bridges. ESR spectroscopy has been used extensively to investigate the properties of monomeric Mov systems, and has shown the participation of this oxidation state in the reactions of the oxomolybdoenzymes (see Section 36.6.7). 

The triazinethiones form sulfur-bridged oligomers by reaction with chlOro-l,3,5-triazines, and are oxidized to yield the dimeric species (53) (66JHC137).,... 

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