CO…HC interactions as packing motifs in the crystals: Part 4. Intermolecular interactions in the structures of N-[(4-arylpiperazin-1-yl)-alkyl]2-azaspiro[4.4]nonane and [4.5]decane-1,3-dione derivatives

In continuation of the studies on weak H-bond formation in N-substituted-spiro-succinimides, the crystal structures of three derivatives from the series of N-methyl-arylpiperazine-spiro-succinimides were examined. Previously and newly studied species differ in the lengths of the distance between imide and aromatic rings. In the described structures methyl-piperazine is located as an aliphatic linker in the place of one atomic group (CH2). It was established that the distance elongation destroyed supramolecular synthons formed in previously studied N-benzyl-spiro-succinimides. The molecules of N-methyl-arylpiperazine-spiro-succinimides are joined predominantly in dimmers via two types of weak H-bonds: CO…HC(sp3) and CO…HC(arom). In the bonds with Csp3 piperazine carbon atoms are mainly involved.