Conversion of di-aryl-chalcones into 4,5-di-hydro-pyrazole-1-carbo-thio-amides: mol-ecular and supra-molecular...

Chalcones of type 4-XC₆H₄C(O)CH=CHC₆H₄(OCH₂CCH)-4, where X = Cl, Br or MeO, have been converted to the corresponding 4,5-di-hydro-pyrazole-1-carbo-thio-amides using a cyclo-condensation reaction with thio-semicarbazide. The chalcones 1-(4-chloro-phen-yl)-3-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C₁₈H₁₃ClO₂, (I), and 1-(4-bromo-phen-yl)-3-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C₁₈H₁₃BrO₂, (II), are isomorphous, and their mol-ecules are linked into sheets by two independent C-H⋯π(arene) inter-actions, both involving the same aryl ring with one C-H donor approaching each face. In each of the products (RS)-3-(4-chloro-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C₁₉H₁₆ClN₃OS, (IV), (RS)-3-(4-bromo-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C₁₉H₁₆BrN₃OS, (V), and (RS)-3-(4-meth-oxy-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C₂₀H₁₉N₃O₂S, (VI), the reduced pyrazole ring adopts an envelope conformation with the C atom bearing the 4-prop-2-yn-yloxy)phenyl substituent, which occupies the axial site, displaced from the plane of the four ring atoms. Compounds (IV) and (V) are isomorphous and their mol-ecules are linked into chains of edge-fused rings by a combination of N-H⋯S and C-H⋯S hydrogen bonds. The mol-ecules of (VI) are linked into sheets by a combination of N-H⋯S, N-H⋯N and C-H⋯π(arene) hydrogen bonds. Comparisons are made with the structures of some related compounds.