Hydrogen-bonded chains of ring in 3-tert-butyl-1-phenyl-7-(-4-trifluoro-methylbenzyl)-4,5,6,7-tetrahydro-1H-Pyrazolo[3,4-b]pyridine-5-spiro-1 '-cyclohexane-2 ',6 '-dione and 3-tert-butyl-7-(4-methoxybenzyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]-pyridine-5-spiro-1 '-cyclohexane-2 ',6 '-dione

In each of 3-tert-butyl-1-phenyl-7-(4-trifluoromethylbenzyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C29H30F3N3O2, (I), and 3-tert-butyl-7-(4-methoxybenzyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo-[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C29H33N3O3, (II), the reduced pyridine ring adopts a half-chair conformation. The molecules of compound (I) are linked by two C-H center dot center dot center dot O hydrogen bonds to form a C(5)C(5)[R-2(1)(8)] chain of rings, while in compound (II), two C-H center dot center dot center dot O hydrogen bonds link the molecules into a C(6)C(7)[R-2(2)(11)] chain of rings, which is further reinforced by a C-H center dot center dot center dot pi hydrogen bond. The significance of this study lies in its observation of significant differences in hydrogen-bonded structures consequent upon very minor changes in remote substituents.