Quantum Chemical Conformational Analysis and X-Ray Structure of 4-Methyl-3-thiosemicarbazide

Chambers, C. C.; Archibong, E. F.; Mazhari, S. M.; Jabalameli, A.; Zubkowski, J. D.; Sullivan, R. H.; Valente, E.; Cramer, C. J.; Truhlar, D. G.
J. Mol. Struct. (Theochem) 1996, 388, 161.

We present X-ray crystallographic results and gas-phase electronic structure calculations of the geometry of 4-methyl-3-thiosemicarbazide. Using Hartree- Fock theory with a 6-31G* basis set, we calculated relative energies for eight different conformations. For the lowest-energy conformations of each of the four possible combinations of rotamers about the two C-N bonds, we also included electron correlation by Møller-Plesset second-order (MP2) perturbation theory with the same basis set. From these calculations, we selected the lowest-energy structure and calculated structural parameters at the MP2 level of theory with the larger correlation-consistent cc-pVDZ basis set. The geometry of the minimum- energy gas-phase structure is in good agreement with the structure observed experimentally in the crystal.

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