Crystal Structure Analysis of 4-Oxo, 4-hydroxy- and 4-alkyl-7-bromopyrazolo[5,1-c][1,2,4]triazines

The crystal structures of 8-R(1)-7-bromo-3-tert-butyl-1-R(2)-pyrazolo[5,1-c][1,2,4]triazin-4(1H)-ones 1a–c, 2a,c (R(1) = CN, CO(2)Et, NO(2), R(2) = H, 1:1 and 3:1 solvates with DMSO; R(1) = CN, CO(2)Et, R(2) = CH(2)Boc), 8-R(1)-7-bromo-3-tert-butyl-1-R(2)-1,4-dihydropyrazolo[5,1-c][1,2,4]triazin-4-ols 3a,b (R(1) = CN, R(2) = n-Bu; R(1) = Br, R(2) = CH(2)Boc), 1,4-dihydro- and aromatic 7-R(3)-3-tert-butyl-4-R(4)-8-methylpyrazolo[5,1-c][1,2,4]triazines 5a,b, 6 (R(3) = H, R(4) = n-Pr; R(3) = Br, R(4) = n-Bu) were investigated by X-ray diffraction analysis. The structural preferences and different packing modes based on the intermolecular interactions were analyzed by the Hirshfeld surface and energy framework analysis. GRAPHICAL ABSTRACT: The crystal structures of ten 3-tert-butyl-4-oxo, 4-hydroxy- and 4-alkyl-7-bromopyrazolo[5,1-c][1,2,4]triazines including non-solvated, 1:1 and 3:1 solvates with DMSO were investigated by single crystal X-ray diffraction, Hirshfeld surface and energy framework analyses. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10870-022-00973-x.