Further crystallographic evidence of NH� � �? (system) and CO� � �? (system) interactions: The structures of bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhC?NNH?C(O)}2CH2] (Ar = Ph, 2-C5H4N, 2-C4H3S)

Supramolecular frameworks assembled via intermolecular lone pair-aromatic interaction between carbonyl and pyridyl groups

“…The lp/p interaction involving the carbonyl group is a subject of current interest. 14 Such contact between the carbonyl and arene ring moieties has been established directly through single- 15 as well as in protein crystals reported by Christianson et al 16 The C]O/p(arene) interaction generally takes the geometrical arrangements shown in Scheme 1, with the mean O/p(ring centroid) distance d lying within the range of 2.8$3.3 A ånd the mean C]O/p(ring centroid) angle a varying between 134 and 176 . 2, [15][16][17] Related interactions between carbonyl and p/acidic amides, such as the N-alkyl substituted derivatives of isocyanurate, barbituric acid and uracil, are also well characterized.…”

“…14 Such contact between the carbonyl and arene ring moieties has been established directly through single- 15 as well as in protein crystals reported by Christianson et al 16 The C]O/p(arene) interaction generally takes the geometrical arrangements shown in Scheme 1, with the mean O/p(ring centroid) distance d lying within the range of 2.8$3.3 A ånd the mean C]O/p(ring centroid) angle a varying between 134 and 176 . 2, [15][16][17] Related interactions between carbonyl and p/acidic amides, such as the N-alkyl substituted derivatives of isocyanurate, barbituric acid and uracil, are also well characterized. 17 Notably, although a thorough CSD search indicated that C]O/p interaction between carbonyl and aromatic nitrogen heterocycles is of wide occurrence, its role in the construction of supramolecular frameworks is seldom discussed.…”

“…These values lie within the range of 2.8$3.3 A ˚for O/p(arene centroid) distances in organic crystals. 2, [15][16][17] Along the a direction, adjacent Cu(L) 2 2+ units are packed in a head-to-tail fashion through a pair of parallel C]O/p interactions to form an infinite chain (Fig. S1 in the ESI).…”

“…‡ Among organic crystals, the C]O/p(arene) interaction is generally found to stabilize the whole self-assembled supramolecular framework together with hydrogen bonding. [15][16][17] It is noteworthy that no other non-covalent interaction exists in complex 1 except for C]O/p(pyridyl).…”

Supramolecular Assemblies Generated from Both Lone-Pair···π and C−H···π Binding Interactions

“…Each molecule of 1 interacts with four neighboring molecules by means of two Cl···π associations (the distance Cl17···centroid A is 3.396(1) Å; Figure ) and two weak C−H···phenyl supramolecular bonds (the distance H36A···centroid B is 2.935(2) Å; Figure and Table ). The C−H···π contact distance is typical for this type of interaction, , and the Cl(l.p.)···π separation is in the range of the calculated values , and also in the range of the few experimental examples so far reported. ,, However, the angle θ (which corresponds to the angle between the Cl, the ring centroid, and the aromatic plane; see Table ) is 71.86°, which is 28° below the ideal value of 90°, , and thus indicative of weak Cl···π interactions.

1 ORTEP drawing and atom numbering of compound 1 .

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