Vibrational spectra carboxylate complexes

Based on a study of the reaction of diethylstannyl dicaprylate with some carboxylic acids (oleic, caprylic, caproic add, etc.) it was suggested that oleic acid tends to displace caprylic acid from the inner sphere of a carboxylate-type complex forming a sufficiently stable complex with tin. The spectrum of the initial diethylstannyl dicaprylate revealed a band at 1600 cm-1 which is intermediate between 1570 and 1720 cm-1. The latter bands are associated with vibrations of bonds... 

Vibrational spectroscopy is the method of choice for the characterizing functional groups in complex organic molecules. Infrared transmission spectroscopy has been used on dried humics pressed into KBr pellets to determine the relative carboxylate content of humic materials (14-16). However, interferences arise from the presence of water bands and possible alterations of the samples under the high pressures used to form the pellets. Diffuse-reflectance techniques can avoid some of the difficulties associated with the KBr pressed-pellet method (9,17-18). To obtain a spectrum analogous to an absorption spectrum, the data are transformed from reflectance units to Kebulka-Munk (K-M) units. However, K-M units are related to... 

The situation is different for the deposit trinuclear Ru hexaacetate complex without M-M bonds. The IR spectrum of this complex contains no characteristic absorption bands of carboxyl groups. In the range of the carrier s stretching vibrations, we observe the same changes as described above for immobilized binuclear Ru tetraacetate. Thus, in contrast to binuclear complexes with the M-M bond, we may suppose that heterogenization of the trinuclear acetate complex without Ru-Ru bonds is accompanied by decomposition the initial complex turns into a mononuclear one, and the acetate groups are substituted by the carrier s amino groups. 

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