Infrared Spectra of Metal Chelate Compounds. IX. A Normal Coordinate Analysis of Dithiocarbamato Complexes

Abstract

The infrared spectra of dithiocarbamato and N-alkyldithiocarbamato complexes with various metals have been obtained in the range between 4000 and 280 cm-I • The spectra of their deuterated forms have also been obtained to confirm the band assignments. A normal-coordinate analysis has been carried out for the 1:1 (metal/ligand) model of the dithiocarbamato Pt ll complex. The results indicate that the Pt-S stretching bands are at 375 and 288 cm-I and the corresponding Pt-S stretching force constant is 2.1 X1()5 dyn/cm. The effects of changing the metal and of alkyl substitution on the electronic structure of these compounds have been inferred from the infrared spectra. . TABLE III. Force constants (10· dyn/cm).

Normal coordinate analysis of the copper center of azurin and the assignment of its resonance Raman spectrum.

“…The structural model for beginning this analysis was based upon early crystallographic and spectroscopic results that indicated a Cu-N2SS' ligand set of approximate tetrahedral geometry. The bond lengths chosen for this analysis were those taken from EXAFS data analyses for two Cu (29,(30)(31)(32)(33) and 369 cm-') and the higher frequency component of the two broad bands (261 cm-') which had been proposed (20) …”

Normal coordinate analysis of dialkyldithiocarbamate and its selenium analogue

“…The bands at 1438, 820, 622, and 375 crn-' in Pt(%2CWH2)2 for C h P d stretching, C====S stretching, C-S stretching, and M-S stretching, respectively, are observed at 1560,665, 612, and 357 cm-' in W-methyldithiocarbamate complex (5). It is argued that since the electron donating tendency of the aIkyl group is expected to increase the E==W bond order and '"ecrease the C-S and Pt-S bond orders", the direction of the band shifts in W-alkyldithiocarbamate is in accordance with the predictions (5).…”

“…The force constants are of the same The calculation has been made for 1 : 1 complex order as that used by Nakamoto et ul. (5). The observed and calculated frequencies of nickel as shown in Fig.…”

“…A few papers (1)(2)(3)(4)(5)(6)(7)(8)(9) have appeared since the publication of the infrared spectral studies of dithiocarbamate complexes of metals by Chatt et al (lo), where dithiocarbamate acts as a uninegative bidentate ligand. The chief interest has been the C==N stretching frequency which occurs around 1480-1550 cm-l, which helps in estimating the contribution of each of the three canonical forms to the total structure.…”

“…Very few investigators (5-9) mention one or two bands other than C=N. Nakamoto et al ( 5 ) , however, studied the infrared spectra of metal complexes of S,CNH,-and S,CNHR-(R being an alkyl group) and assigned their spectra on the basis of a normal coordinate treatment made for Pt(S,CNH,),, 1 : 1 complex. In spite of this, it has been found difficult to assign metal-sulfur and other frequencies in dialkyldithiocarbamate complexes (7,8).…”