Five-membered heterocycles. Part II. Crystal structures and HOMA index calculations for selected 1,3,4-thiadiazole derivatives

Aromaticity in heterocycles: new HOMA index parametrization

“…Mrozek and co-workers [24][25][26][27], in their study, on the HOMA of five-membered heterocyles using bond length from X-ray, also found that in the rHOMA index isoxazoles and oxazoles are not aromatic compounds and furans are classified as anti-aromatic compounds. From the results described in Table 5, it is possible to state that for six-membered heterocycles, there is a variation of aromaticity with the variation in number and position of nitrogen.…”

3-Methyl-5-methylsulfanyl-1,3,4-thiadiazole-2(3H)-thione

“…We ended up with two structures built around a 1,3,4-thiadiazole-2(3H)-thione ring, viz, 2,5-dimercapto-thiadiazole (Bats, 1976; (II)) and 2-thioxo-5-(ethylthio)-3H-1,3,4-thiadiazole. (Mrozek et al, 2000;(III)) which differ from the title compound just in the substitutents on the ring (Fig. 5).…”

“…For the reactivity of thiadiazole, see: Espinosa et al (2010). For significance of weak SÁ Á ÁS interactions and for the role of weak interactions in the absence of stronger ones, see: Allen (2002); Bats (1976); Bondi (1964); Desiraju & Steiner (1999); Mrozek et al (2000); Iwaoka & Isozumi (2012). 167 parameters H-atom parameters constrained Á max = 0.25 e Å À3 Á min = À0.27 e Å À3 Table 1 Selected interatomic distances (Å ).…”

N-(5-Methylsulfanyl-1,3,4-thiadiazol-2-yl)acetamide

“…For the applications of 1,3,4-thiodiazole and its derivatives in antimicrobial drugs and in the construction of metal-organic frameworks, see: Gardinier et al (2007); Mrozek et al (2000); Xue et al (2008). For the synthesis, see: Clerici & Pocar (2001).…”

“…Guo-Ying Zhang S1. Comment 1,3,4-Thiodiazole is important for biological systems, and its derivatives have attracted widespread interest due to their further expanded application in antimicrobial drugs and in the construction of some interesting metal-organic frameworks (Gardinier et al, 2007;Mrozek et al, 2000;Xue et al, 2008). Recently, we synthesized a new thiodiazole-ligand, namely 2-acetamido-5-methylmercapto-1,3,4-thiodiazole, (I).…”