The compoundsN′-benzylidene-N-methylpyrazine-2-carbohydrazide, C13H12N4O, (IIa),N′-(2-methoxybenzylidene)-N-methylpyrazine-2-carbohydrazide, C14H14N4O2, (IIb),N′-(4-cyanobenzylidene)-N-methylpyrazine-2-carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc),N-methyl-N′-(2-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IId), andN-methyl-N′-(4-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55–78°. These methylated pyrazine-2-carbohydrazides have supramolecular structures which are formed by weak C—H...O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π–π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0–6°.
化合物N′-亚苄基-N-甲基吡嗪-2-甲酰肼,C13H12N4O,(IIa),N′-(2-甲氧基亚苄基)-N-甲基吡嗪-2-甲酰肼、C14H14N4O2,(IIb),N′-(4-氰基亚苄基)-N-甲基吡嗪-2-甲酰肼二水合物,C14H11N5O-2H2O,(IIc)、N-甲基-N′-(2-硝基亚苄基)吡嗪-2-甲酰肼,C13H11N5O3,(IId) 和 N-甲基-N′-(4-硝基亚苄基)吡嗪-2-甲酰肼,C13H11N5O3,(IIe) 吡嗪环和苯环之间的二面角在 55-78° 之间。这些甲基化吡嗪-2-甲酰肼具有由弱 C-H...O/N 氢键形成的超分子结构,只有水合的 (IIc) 除外。所有五种化合物都存在 π-π 堆叠相互作用。将其中三种结构与它们的非甲基化对应物进行比较,发现吡嗪环和苯环之间的二面角范围为 0-6°。