Hydrogen-bonding patterns in 3-alkyl-3-hydroxyindolin-2-ones.

The molecules of racemic 3-benzoylmethyl-3-hydroxyindolin-2-one, C(16)H(13)NO(3), (I), are linked by a combination of N-H...O and O-H...O hydrogen bonds into a chain of centrosymmetric edge-fused R(2)(2)(10) and R(4)(4)(12) rings. Five monosubstituted analogues of (I), namely racemic 3-hydroxy-3-[(4-methylbenzoyl)methyl]indolin-2-one, C(17)H(15)NO(3), (II), racemic 3-[(4-fluorobenzoyl)methyl]-3-hydroxyindolin-2-one, C(16)H(12)FNO(3), (III), racemic 3-[(4-chlorobenzoyl)methyl]-3-hydroxyindolin-2-one, C(16)H(12)ClNO(3), (IV), racemic 3-[(4-bromobenzoyl)methyl]-3-hydroxyindolin-2-one, C(16)H(12)BrNO(3), (V), and racemic 3-hydroxy-3-[(4-nitrobenzoyl)methyl]indolin-2-one, C(16)H(12)N(2)O(5), (VI), are isomorphous in space group P-1. In each of compounds (II)-(VI), a combination of N-H...O and O-H...O hydrogen bonds generates a chain of centrosymmetric edge-fused R(2)(2)(8) and R(2)(2)(10) rings, and these chains are linked into sheets by an aromatic pi-pi stacking interaction. No two of the structures of (II)-(VI) exhibit the same combination of weak hydrogen bonds of C-H...O and C-H...pi(arene) types. The molecules of racemic 3-hydroxy-3-(2-thienylcarbonylmethyl)indolin-2-one, C(14)H(11)NO(3)S, (VII), form hydrogen-bonded chains very similar to those in (II)-(VI), but here the sheet formation depends upon a weak pi-pi stacking interaction between thienyl rings. Comparisons are drawn between the crystal structures of compounds (I)-(VII) and those of some recently reported analogues having no aromatic group in the side chain.