edited bv L. GILBERT
GEORGE
Denison University Granville, Ohio 43023
Spectroscopy Illustrated SVEM~TTED BY:
Erwin Boschmann Indiana University-Purdue University at Indianapolis. IN 46202 CHECKED BY:
George Wollaston Clarion State College Clarion. PA 16214
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The theory and importance of spectroscopy have been discussed widely (see, for instance, ref. ( 4 ) ) . One of the important areas of suectroscouv, . . infrared spectroscopy, . . records t h e frt.quer~cyo t v i l n ~ r i o t ~ hundeil at..ms, thus permitring thcstudy ~f the I I ~ L I W (11 bundin): I ~ Q I W Q P I ~ rhese at~mlr.'l'her
Sultoxids Absorptions of some DMSO Compounds Compound DMSO CuC12.2DMS0 SnClc2DMSO PdCIo.2DMSO
S=D
band, cm-' 1050 923 920,905 1120
Copper (11)chloride (1.34 g, 0.010 moles) is dissolved in 10 mi of ethanol. The solution is stirred and treated with 2.0 ml (0.026 moles) of DMSO. The immediate exothermic reaction yields a light green precipitate. The mixture is stirred for several more minutes, filtered, washed with cold ethanol. and finallv reervstallized from hot ethanol. organic solvents. SnCId.2DMS0
Ten milliliters (0.085 mule) of SnC4 (or 30.0 g of SnClc5H20) are dissolved in 25 ml distilled water. The clear colorless solution is stirred and treated with 3.0 ml(0.042 mole) of DMSO. A white orecioitate forms immediatelv as the result of an exothermicreaction. he mix-
research ( I ) . Caution-Avoid contact of DMSO w i t h skin o r t h e prolonged breathing of its vapors! Use of plastic or rubber gloves is recommended
ethanol
CuC12 + ~ ( C H ~ Z S O
TestedDemonstrations is a monthly feature designed to present lecture demonstrationsand experiments in a format convenient for classroom use. Readers interested in either submitting or checking demonstrations should contact the mlumn editor. An outline of format requirements was given an p. 166 Of the March 1976 issue of THIS JOURNAL.
CuC12. 2(CHs)zSO
Volume 60 Number 5
May 1983
413
saluhility of the product in water, the ~ i e l d(based on DMSO) is a function of the number of washings hut can be expected to he from 2.0-5.0 g (23-58%).SnClc2DMS0 is a white powder-like,air-stable solid, soluble in acetone,somewhat soluble in water, but only slightly soluhle in most other common solvents. It is stable toward hydrolysis, does not melt ar decompose below 300°, even after 24 hr, and can he sublimed cleanly at 180'.
and the observed absorption shift to lower frequencies. Most known metal-DMSO compounds bond through oxygen. PdClr2DMS0 is an exception: its sulfoxide absorption appears a t a value higher than that for pure DMSO. This implied strengthening of the original S=O bond is explained (2) by metal bond formation through sulfur (CHs)2-0-PdC12
t
S
A total of 0.632 g (0.003 mole) of finely powdered PdClz are sprinkled into 5 ml of DMSO with stirring. The solution immediately attams a dark coloration and gradually yields the orange product. The mixture is allowed to stir for 3 4 hr to complete the reaction. Any unreacted PdClz is easily separated from the product by decanting the supernatant complex-DMSO mixture. This mixture is then filtered, and the product purified by removing the excess DMSO under vacuum or through repeated washings with ether. The yield is about 0.8 g (80%).PdCI2.2DMSO is an air-stable orange solid which decomposes at 160'. It is slightly soluble in common polar solvents, very slightly soluble m ether, and insoluble in common nonpolar solvents.
Spectral Interpretations
The infrared spectra of the compounds may be recorded as Nujol mulls or KBr pellets using any mid-region spectronhotometer. The firmre dis~lavsthe spectrum for pure DMSO. ~ S = Oabsorption banda
