Solvation of AlCl3 in deuterated acetonitrile studied by means of vibrational spectroscopy.
Large blue shifts of the nu2 C=N stretch, nu4 Cz.sbnd;C stretch, and nu8 CCN deformation bands of CD3CN are observed in the infrared and Raman spectra of CD3CN solution of AlCl3, resulting from the donor-acceptor interactions of CD3CN with the Lewis acid. The Raman spectrum in the nu2 region shows further details; two new bands emerge on the blue side of the nu2 band of free CD3CN, and the ratio in intensity of the two bands also changes with concentration. Parallel to the nu2 region, similar new bands are observed on the blue sides of the nu4 and nu8 bands of free CD3CN. The solvation number of AlCl3, determined from the Raman intensities of the C=N stretch bands for free and coordinated CD3CN, increases from 1.54 to about 1.7 with decreasing concentration, indicating that various complexes with different numbers of coordinated acetonitrile coexist in the solution. The strong hydrogen bonds formed between the CD3 group and the chlorine atoms of the solute result in a large band appearing on the low frequency side of the nu1 CD3 symmetric stretch of free CD3CN.
Seo
Jun-Sik
JS
Department of Chemistry, University of Incheon, 177 Dohwa-dong, Nam-ku, Incheon 402-749, South Korea.
Kim
Kang-Woo
KW
Cho
Han-Gook
HG
D000097:Acetonitriles; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003903:Deuterium; D006860:Hydrogen Bonding; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
D000097:Acetonitriles; D017607:Aluminum Compounds; D002712:Chlorides; D012997:Solvents; D000077410:Aluminum Chloride; D003903:Deuterium; C032159:acetonitrile