1-Benzyl-3,3-dichloro-1H-indol-2(3H)-one

The title compound, C₁₅H₁₁Cl₂NO, was synthesized from N-­benzyl­isatin. The compound crystallizes as stacks of mol­ecules running down the c axis. Mol­ecules within each of these stacks inter­act with each other through π–π and C—H...π inter­actions, and inter­act with neighbouring stacks through C—H...O inter­actions.

2-{[(4-Methyl­phen­yl)sulfon­yl]amino}­phenyl 4-methyl­benzene­sulfonate

The title compound, C₂₀H₁₉NO₅S₂, crystallizes as an almost 2:1 mixture of two mol­ecular orientations (described as Orient-A and Orient-B). The consequences of these two orientations is the formation of three types of N—H...O hydrogen-bonded dimers in which the (Orient-A + Orient-A) dimers are likely to be the most stable, while the mixed (Orient-A + Orient-B) dimers are more frequent. Extra inter­actions in the form of C—H...O and C—H...π inter­actions act to further stabilize these dimers and probably allow the less energetically favourable (Orient-A + Orient-B) and (Orient-B + Orient-B) hydrogen-bonded dimers to exist by preventing their conversion to (Orient-A + Orient-A)-only hydrogen-bonded dimers during the crystal-growth process.

Hydrogen-bonding patterns in enamino­nes: (2Z)-1-(4-bromo­phen­yl)-2-(pyrrolidin-2-yl­idene)ethanone and its piperidin-2-yl­idene and azepan-2-yl­idene analogues

The title compounds, namely (2Z)-1-(4-bromo­phenyl)-2-(pyrrolidin-2-yl­idene)ethanone, C₁₂H₁₂BrNO, (I), (2Z)-1-(4-bromo­phenyl)-2-(piperidin-2-yl­idene)ethanone, C₁₃H₁₄BrNO, (II), and (2Z)-2-(azepan-2-yl­idene)-1-(4-bromo­phenyl)­ethan­one, C₁₄H₁₆BrNO, (III), are characterized by bifurcated intra- and inter­molecular hydrogen bonding between the secondary amine and carbonyl groups. The former establishes a six-membered hydrogen-bonded ring, while the latter leads to the formation of centrosymmetric dimers. Weak C—H...Br inter­actions link the individual mol­ecules into chains that run along the [011], [101] and [101] directions in (I)–(III), respectively. Additional weak Br...O, C—H...π and C—H...O inter­actions further stabilize the crystal structures.