TY - JOUR
T1 - Non-bonded interactions in 2,2,4,4-tetramethyl-1,3-cyclobutanedithione and 2,2,4,4-tetramethyl-3-thio-1,3-cyclobutanedione
AU - Basu, P. K.
AU - Singh, U. Chandra
AU - Tantry, K. N.
AU - Ramamurthy, V.
AU - Rao, C. N.R.
N1 - Funding Information:
The authors thank the Department of Science and Technology of India) and the National Institutes of Health (Grant 01-136-N) of this research, and Dr. J. C. Green of the University of Oxford with the photoelectron spectra.
PY - 1981/5
Y1 - 1981/5
N2 - Electronic absorption and emission spectra as well as He(I) photoelectron spectra of 2,2,4,4-tetramethyl-1,3-cyclobutanedithione and 2,2,4,4-tetramethyl-1-3-thio-1,3-cyclobutanedione have been interpreted on the basis of molecular orbital calculations. The results show that the non-bonded orbital of the dithione is split owing to through-bond interaction, the magnitude of splitting being 0.4 eV. The π* orbital of the dithione appears to be split by about 0.2 eV. Electronic absorption spectra show evidence for the existence of four n-π* transitions, arising out of the splitting of the orbitals referred to above, just as in the case of 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Electronic and photoelectron spectra of the thio-dione show evidence for weak interaction between the CS and C&.zdbnd;O groups, probably via π* orbitals. Infrared spectra of both the dithione and the thio-dione are consistent with the planar cyclobutane ring; the ring-puckering frequency responsible for non-bonded interactions is around 67 cm-1 in both the dithione and the thio-dione, the value not being very different from that in the dione. The 1,3-transannular distance is also similar in the three molecules.
AB - Electronic absorption and emission spectra as well as He(I) photoelectron spectra of 2,2,4,4-tetramethyl-1,3-cyclobutanedithione and 2,2,4,4-tetramethyl-1-3-thio-1,3-cyclobutanedione have been interpreted on the basis of molecular orbital calculations. The results show that the non-bonded orbital of the dithione is split owing to through-bond interaction, the magnitude of splitting being 0.4 eV. The π* orbital of the dithione appears to be split by about 0.2 eV. Electronic absorption spectra show evidence for the existence of four n-π* transitions, arising out of the splitting of the orbitals referred to above, just as in the case of 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Electronic and photoelectron spectra of the thio-dione show evidence for weak interaction between the CS and C&.zdbnd;O groups, probably via π* orbitals. Infrared spectra of both the dithione and the thio-dione are consistent with the planar cyclobutane ring; the ring-puckering frequency responsible for non-bonded interactions is around 67 cm-1 in both the dithione and the thio-dione, the value not being very different from that in the dione. The 1,3-transannular distance is also similar in the three molecules.
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U2 - 10.1016/0166-1280(81)85001-4
DO - 10.1016/0166-1280(81)85001-4
M3 - Article
AN - SCOPUS:49149138185
VL - 76
SP - 237
EP - 250
JO - Computational and Theoretical Chemistry
JF - Computational and Theoretical Chemistry
SN - 2210-271X
IS - 3
ER -