Molecular conformation and supramolecular aggregation in two fused pyrazoles: -stacked R (6) dimers in 2,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, and sheets of alternating R (12) and R (48) rings in 3-tert-butyl-4′,4′-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1′-cyclohexane-2′,6′-dione
In 2,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, C13H15N3O, (I), the heterobicyclic system is planar and exhibits peripheral ten -electron delocalization. In 3-tert-butyl-4′,4′-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H- pyrazolo[3,4-b]pyridine-5-spiro-1′-cyclohexane-2′,6′-dione, C23H25N3O2, (II), the pyrazole ring exhibits marked bond fixation, while the reduced pyridine ring adopts a half-chair conformation. Molecules of (I) are linked into centrosymmetric (6) dimers by a single C—H…N hydrogen bond [H…N = 2.50 Å, C…N = 3.3397 (17) Å and C—H…N = 148°], and these dimers are linked into chains by a single – stacking interaction. In (II), the combined action of one N—H…O hydrogen bond [H…O = 2.40 Å, N…O = 3.2248 (15) Å and N—H…O = 157°] and one C—H…O hydrogen bond [H…O = 2.48 Å, C…O = 3.407 (2) Å and C—H…O = 164°] links the molecules into sheets built from alternating centrosymmetric (12) and (48) rings; there is a weak C—H…N interaction [H…N = 2.60 Å, C…N = 3.5149 (18) Å and C—H…N = 154°] between molecules in adjacent sheets.
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Document Type: Research Article
Publication date: 2004-04-01