DMSO molecules

The oxidation of 3-substituted indole to oxindoles can also be done with a mixture of DMSO and cone, hydrochloric acid[6-9]. This reaction probably involves a mechanism similar to the halogenation with a protonated DMSO molecule serving as the electrophile[10]. 

There is some reason36 to believe that this noticeable change in the reactivity of AN in DMSO solution, is caused by the dipole-dipole interaction of the nitrile group of AN with the sulfinyl group of the DMSO molecule, resulting in an appreciable... 

H). As shown, a disordered structural model was obtained for the guest. The model comprises two mirror-related guest molecules. The oxygen atom and the proximal methyl C-atom are practically overlapping the same atomic positions in both orientations. However, the sulphur atomic positions do not average in the X-ray data and show a nearly 50/50 occupancy. As indicated by the comparison of the respective bond distances and intra-associate contact distances of the DMSO molecule (Table 17), the effect of disorder is serious (e.g. the S=0 distances appear abnormally short in the 20 DMSO instance). This precludes the possibility of assessing interaction between the O atom of the carboxyl and a methyl of dimethyl sulfoxide. 

Formulating an acceptable chemical mechanism for each pathway is an interesting challenge. In aid of that, in the reaction with L = Me2SO, intermediate 17 was isolated and fully characterized. It has a structure in which one dmso molecule is coordinated to a rhenium atom of 6 trans to its oxo group. 

Iodides of soft metal ions such as mercury (II) are essentially un-ionized in dimethylsulfoxide 54). This feature is due both to the strength of the Hg-I bond and the weakness of the Hg-DMSO bond which appears to occur through the sulfur atom of the DMSO molecule, as is known for the palladium (II) complex 5S). 

It has been mentioned that the donicity rule does not hold for typical soft-soft interactions. In particular, DMSO behaves differently towards soft metal ions and coordination is achieved through the soft end of the DMSO molecule. Whereas iodides of hard metal ions are completely ionized in DMSO, the iodides of soft metal ions tend to remain non-ionized in DMSO-solutions. Hgl2 is scarcely ionized in DMSO and shows a high tendency to react with iodide ions S4>86>87),... 

Fig. 2.3 Arrhenius ( ) and Eyring ( ) plots of data for the exchange of a single dmso molecule with Ga(dmso) + in CD3NO2. Nmr line-broadening was used for the higher temperatures and stopped-flow nmr experiments for the lower temperatures. For the Arrhenius plot, the slope and intercept (at T = 0) are -9.2 x 10 and +31,4 respectively, leading to = 76 kJ mol" and logA = 13.6. For the Eyring plot, the slope and intercept are —8.77 x 10 and +24.4 respeetively, leading to A// = 73 kJ mol" and AS = 5 J K" mol" .

Fig. 10 Crystal packing of tpcb bta (34 33) cocrystal material disordered water and DMSO molecules have been omitted from supramolecular cavity [57]...

An analysis of the Wannier functions in CPMD simulations of one dimethyl sulfoxide (DMSO) molecule dissolved in water was carried out by us in 2004 in order to gain more insight into the unusual properties of the DMSO-water mixture (72). In this special case, we have utilized MLWCs to calculate molecular dipole moments of the DMSO molecule in gas phase and aqueous solution. Comparing those two a large increase of the local dipole... 

Nucleophiles, other than alcohols, can react with the TFAA-activated DMSO molecule—F3CC02-S(+)Me2—, indoles being particularly prone to do so. 

The primary product (29) of the reaction of DMSO and oxalyl chloride decomposes very quickly to 30 even at — 140°C.163 However, the activated DMSO molecule 30 remains stable bellow —20°C, but decomposes above this temperature to chloromethyl methyl sulfide (31), via the reactive species H2C=S(+)-Me. 

During a Swern oxidation, after the formation of the activated DMSO molecule 30, the alcohol is added at low temperature. The alcohol reacts very quickly with activated DMSO, resulting in the formation of an alkoxydi-methylsulfonium chloride (32). 

For experimental convenience, it may be advisable to carry out the reaction at a maximum temperature. As the activated DMSO molecule— compound 30—decomposes above -20°C, it is not possible to use a temperature much higher than this one. On the other hand, the stability of the activated alcohol species 32, being very diverse depending on the concrete... 

The coordination properties of this phosphine-alane were further investigated by Fontaine et al. toward the rhodium(III) precursor [RhCp Me2(DMSO)] (Cp =pentamethylcyclopentadienyl, DMSO = dimethylsulfoxide).78 According to the spectroscopic data, the DMSO molecule is retained in the corresponding complex 96, most probably by interaction of its oxygen atom with the pendant alane moiety (Scheme 55). Trimethylaluminium was added to 96 to trap DMSO and generate complex 97 related to 96. But the competition between the external and... 

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