Sulfoxide complexes structural data

Of particular note is the complex [Fe(CN)5(Me2SO)]3 (226), where the positive shift in i (S=0) upon sulfoxide coordination [Ai>(S=0) = +15 cm-1] is taken as indicative of coordination via sulfur. No structural data appear to be available for confirmation. 

With diphenyl sulfoxide, Ln(DPS0)g(C104)3 complexes containing ionic perchlorate and Ln(DPSO)8l3 for Ln = La-Y have been reported [221,222], The above on repetition yielded Ln(DPS0)7(C104)3 for Ln = Sm, Eu, Yb. This family of complexes lack structural data. 

Hexafluorophosphate derivatives, such as [M(Me2SO)n][PF6]3 (M = La, Lu, Y), have been synthesized (365), and infrared data show O-bonding of the sulfoxide with ionic hexafluorophosphate groups. Analytical data are incomplete for this series, as decomposition, postulated to be to lanthanide fluorides, occurs. The (CH2)4SO complexes [M( CH2 4SO)t.5][PF6]3 are reported (145), which are 3 1 electrolytes with uncoordinated anions, implying a possible semibridged structure, as previously mentioned. Complexes of other cyclic sulfoxides, including thioxane oxide (146) and trans-1,4-dithiane-1,4-dioxide (147) derivatives of hexafluorophosphate salts have also been prepared. 

In order to show that the origin of this difference is not a function of the particular substrate analogue used, similar NMR relaxation studies have been performed with dimethyl sulfoxide (DMSO)1401 since the crystal structure of the enzyme-NADH-DMSO ternary complex is well resolved.1366 From the relaxation data, the distance between the methyl protons of DMSO and Co11 was calculated to be 8.9 0.9 A, again too great for direct coordination of the sulfoxide group to the metal ion. Since the cobalt enzyme appears to be functionally similar to the native enzyme, the difference is unlikely to be a direct result of substitution. One possibility is that there may actually be a difference between the solution and crystalline structure of the enzyme ternary complex, particularly since it is well established that the crystalline enzyme is 1000 times less active than in solution.1402... 

A,A-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), will form complexes with the tin, breaking the polymeric structure of the dioxastannolane but maintaining a coordination number of greater than four at the metal. A m-R2Sn02L structure has been proposed on the basis of 119Sn chemical shifts (—137 to —189 ppm) and Mbssbauer data (A 2.11-2.82 mm/second). The donor ligand is readily lost under reduced pressure (224). 

Numerous oxo-molybdo-bis(dithiolene) and oxo-tungsto-bis(dithiolene) complexes have been synthesized and characterized as potential structural analogues of the active sites of the dimethyl sulfoxide reductase (DMSOR) and aldehyde oxidoreductase (AOR) families of mononuclear Mo and W enzymes [see Fig. 16 and Chapter 10 in this volume (50)]. The available IR and Raman data for the Mo and W complexes are summarized in Tables VII and VIII,... 

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