Ligand dimethylsulfoxide

The coordination number of Ni rarely exceeds 6 and its principal stereochemistries are octahedral and square planar (4-coordinalc) with rather fewer examples of trigonal bipyramidal (5), square pyramidal (5), and tetrahedral (4). Octahedral complexes of Ni arc obtained (often from aqueous solution by replacement of coordinated water) especially with neutral N-donor ligands such as NH3, en, bipy and phen, but also with NCS, N02 and the 0-donor dimethylsulfoxide. dmso (Me2SO). 

Cyano-de-diazoniations of the Sandmeyer type have been used for the synthesis of aromatic nitriles for many decades (example Clarke and Reed, 1964), as cyanide ions are comparable to bromide and iodide in many respects. A homolytic cyano-de-diazo-niation that does not use metal ions as reductant or ligand transfer reagent was described by Petrillo et al. (1987). They showed that substituted diazosulfides (XC6H4 — N2 — SC6H5), either isolated or generated in situ from arenediazonium tetrafluoroborates and sodium benzenethiolate, react with tetrabutylammonium cyanide in dimethylsulfoxide under photon stimulation, leading to nitriles (XC6H4CN). The method worked well with eleven benzenediazonium ions substituted in the 3- or 4-position, and was also used for the synthesis of phthalo-, isophthalo-, and tere-... 

Table 4 shows the NMR coalescence temperatures for this process for a number of ligands. In addition to this data it was shown that the exchange rates for the ligands acetonitrile, dimethylsulfoxide, anddiphenyl-... 

In the case of the DMSO reductase family, as pointed out above, the metal centre is bound to two molecules of the cofactor. DMSO reductase itself catalyses the reduction of dimethylsulfoxide to dimethylsulfide with incorporation of the oxygen atom of DMSO into water. The active site of the oxidized enzyme is an L2MoVI0(0-Ser) centre, which, upon reduction, loses the M=0 ligand to give a L2MoIV(0-Ser) centre. In the catalytic... 

These researchers found that the nucleophilicity of the complex depended on the electronic nature of the porphyrin. While a [(TPFPP)Fe (02)] (TPFPP equals the dianion of me5 o-tetrakis(pentafluorophenyl)porphyrin) complex did not epoxidize alkenes, adding dimethylsulfoxide (DMSO) as an axial ligand restored the complexes nucleophilicity and ability to epoxidize alkenes. The authors ascribed this restored capability to push the side-on peroxo into a more open, end-on, nucleophilic conformation. Watanabe and co-workers... 

Dimethylformamide Dimethylglyoxime mono-anion 2,9-Dimethyl-1,10-phenanthroline Dimethylsulfoxide (upper case for solvent, lower-for ligand)... 

In the majority of cases, the ligand itself is used as a solvent in the synthesis of dimethylsulfoxide complexes. 

Occasionally, the poor solubility of the reagent in aqueous solution is a problem. It usually proves possible to circumvent this difficulty by adding the ligand to the solution of receptor in a small amount of an organic solvent that is miscible with water such as ethanol, dioxane, dimethylsulfoxide or... 

Borabenzene anions can serve as n ligands to a thallium(I) center, as demonstrated by the work of Herberich et al. (183). Reaction of alkali metal borinates with thallium(I) chloride yields the pale yellow, sublimable complexes LVIa,b [Eq. (16)] (see Fig. 11), which are only sparingly soluble in nonpolar aprotic solvents but easily soluble in pyridine and dimethylsulfoxide (183). 

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