Crystal structures of two anhydrous and one hydrated 7-(arylamino)-5-methyl-2-(trifluoromethyl)-[1,2,4]-triazolo-[1,5-a]pyrimidine derivatives

Abstract

Abstract While in both 7-(arylamino)-5-methyl-2-(trifluoromethyl)-[1,2,4]-triazolo-[1,5-a]pyrimidines,1 [1a: aryl=3,5dichlorophenyl; 1b: aryl=2,4-dichlorophenyl), the strongest intermolecular interactions are N–H···N hydrogen bonds, different acceptor atoms are involved leading to different arrangement of molecules. In the case of 1a, N2A–H2A···N4B and N2B–H2B···N3A hydrogen bonds generate tetrameric units, composed of two molecules of each of the independent molecules, Mol A and Mol B. In the case of 1b, N2A–H2A···N4B and N2B–H2B···N4A hydrogen bonds generate C12 chains of alternate molecules A and B. As well as the strong N–H···N hydrogen bonds, there are also weaker π···π, C–X···π (X=Cl, F and H) and C–H···F interactions in 1a, and π···π, C–X···π (X=H and Cl) and C–H···X (X=F and N) interactions in 1b. In {[7-(4-chlorophenylamino)-5-methyl-2-(trifluoromethyl)-[1,2,4]-triazolo-[1,5-a]pyrimidine].(H2 O)}, [1c(H 2 O)], chains, C2 2(16) of alternate molecules of 1c and water are generated from combinations of OW–HW···N and N–H···OW intermolecular hydrogen bonds: also present are π(pyrimidine)···π(chlorophenyl), C–Cl··· π(triazole) and C–F··· π(pyrimidine) interactions. Comparisons with reported [1,2,4]-triazolo-[1,5-a]pyrimidine structures clearly show variations in the N–H···N hydrogen bonding patterns and the significant influence of the type and position of substituents on the supramolecular assemblies generated.