... Scheme 2 Synthesis of 1,3,4-thiadiazines 5 and 7 and 1,3,4-selenadiazines 6 and 8 ... Geometry optimizations were carried out employing the TPSS [18] functional with the def2-TZVP [19] basis set ... 21] version employing the B3LYP [22] functional with the 6-31++G(d,p)-Basis set. ...
[Campbell, Nicole L.; Gillis, Cyril J.; Klapstein, Dieter; Nau, Werner M.; Balfour, Walter J.; Fougere, Scott G. Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy, 1995 , vol. 51, # 5 p. 787 - 798]
