The infrared spectra of N,N-dimethylformamide (DMF) and N,N-dimethylthioformamide (DMTF) have been investigated in the range 4000–250 cm−1. Assignment of the frequencies of DMF has been made on the basis of normal coordinate analysis for DMF, DMF-15N, and DMF-d7 using Urey-Bradly, modified Urey-Bradley, and symmetrized valence force fields. Calculations have been extended to N,N-dimethylthioformamide and N,N-dimethylselenoformamide, using the Urey-Bradley and symmetrized valence force fields. The assignments for DMF from the modified Urey-Bradley field are found to be more satisfactory. The frequency shifts on isotopic substitution and on complexation have been explained. The results of the calculations are discussed in comparison with other related molecules.
The infrared spectrum of N,N-dimethyldithiocarbamate complex of nickel(I1) has been recorded in the range 2000-250 cm-'. Normal coordinate analyses have been made for nickel din~ethyldithio-carbamate and nickel dimethyldiselenocarban~ate colnplexes and their infrared spectra indexed. The frcquency shifts observed on alkyl substitution have been discussed. The M-Se stretching frequency occurs about 100 cm-' lower in the diselenocarba~nate con~plex as compared to M-S frcquency of the dithiocarbamate.
A simple method for the preparation of the yellow diamagnetic complex, (NH4)3[VO2·(C2O4)2]·2H2O, is described. Around 200°C, the complex suffers decomposition, giving a bluish-grey paramagnetic compound (NH4)2·[(VO)2(C2O4)3]. The infrared spectrum of the yellow complex shows a covalent bonding between vanadium and the oxalate groups.
The absorption in the ultraviolet region is due to the electron transfer within the VO2 group. An octahedral structure, with the two linearly-arranged oxide oxygens at unequal lengths from vanadium(V), is suggested for the complex anion.
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