Crystal structures of the dioxane hemisolvates ofN-(7-bromomethyl-1,8-naphthyridin-2-yl)acetamide and bis[N-(7-dibromomethyl-1,8-naphthyridin-2-yl)acetamide]

Abstract

Supporting information: this article has supporting information at journals.iucr.org/eCrystal structures of the dioxane hemisolvates of N-(7-bromomethyl-1,8-naphthyridin-2-yl)acetamide and bis [N-(7-dibromomethyl-1,8-naphthyridin-2-yl) The syntheses and crystal structures of N-(7-bromomethyl-1,8-naphthyridin-2-yl)acetamide dioxane hemisolvate, C 11 H 10 BrN 3 OÁ0.5C 4 H 8 O 2 , (I), and bis[N-(7-dibromomethyl-1,8-naphthyridin-2-yl)acetamide] dioxane hemisolvate, 2C 11 H 9 Br 2 N 3 OÁ0.5C 4 H 8 O 2 , (II), are described. The molecules adopt a conformation with the N-H hydrogen pointing towards the lone electron pair of the adjacent naphthyridine N atom. The crystals of (I) are stabilized by a three-dimensional supramolecular network comprising N-HÁ Á ÁN, C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, as well as C-BrÁ Á Á halogen bonds. The crystals of compound (II) are stabilized by a three-dimensional supramolecular network comprising N-HÁ Á ÁN, C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, as well as C-HÁ Á Á contacts and C-BrÁ Á Á halogen bonds. The structure of the substituent attached in the 7-position of the naphthyridine skeleton has a fundamental influence on the pattern of intermolecular noncovalent bonding. While the Br atom of (I) participates in weak C-BrÁ Á ÁO guest and C-BrÁ Á Á contacts, the Br atoms of compound (II) are involved in host-host interactions via C-BrÁ Á ÁO C, C-BrÁ Á ÁN and C-BrÁ Á Á bonding. Chemical contextIn recent decades, 1,8-naphthyridines have attracted increasing interest because of their biological and medicinal activities (Ferrarini et al., 1998;Roma et al., 2010;Badaweh et al., 2001;Litvinov, 2004), as ligands in the synthesis of metal complexes (Tang et al., 2015;Matveeva et al., 2013;Kolotuchin & Zimmerman, 1998) and as building blocks for various supramolecular systems (Kolotuchin & Zimmerman, 1998;Park et al., 2005;Liang et al., 2012). Compound (I) represents a useful precursor for the synthesis of artificial receptor molecules, for example, for carbohydrate receptors bearing naphthyridine units (Mazik & Cavga, 2007;Mazik & Sicking, 2001;Cuntze et al., 1995). Structural commentaryThe molecular structures of the title compounds, (I) and (II), are illustrated in Figs. 1 and 2, respectively. The asymmetric unit of compound (I) consists of one molecule of the naphthyridine derivative and one half of a 1,4-dioxane solvent molecule, with the whole molecule being generated by inversion symmetry. The naphthyridine ring of the host molecule is essentially planar [maximum deviations from the mean plane being 0.034 (3) Å for N1 and À0.034 (3) Å for C6]. The plane defined by the acetamido group is inclined at an angle of 18.9 (2) with respect to the mean plane of the 1,8-naphthyr- idine moiety. The torsion angle along the atomic sequence N2-C1-C9-Br1 is 83.6 (4) . The dioxane molecule is connected to the host molecule via C-HÁ Á ÁO hydrogen bonding (Table 1 and Fig. 1).The asymmetric unit of the inclusion compound (II) contains two crystallographically independent, but conformationally similar ...

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“…It should be noted at this point that among the numerous reports in the literature dealing with the nature of halogen bonds, triangular X 3 interactions are observed in an only small number of crystal structures of halogen compounds and their occurrence appear to be strongly influenced by the geometry of the molecule. Molecules with C 3 v symmetry such as trihalomesitylenes[35b], [35c] (X = Cl, Br, I) provide a perfect arrangement of halogen atoms for cooperative X ··· X interactions.…”

“…The isostructurality of the crystals of 1 and 2 implicates similarities regarding the molecular arrangement and the patterns of non‐covalent intermolecular bonding. In the crystal structure of 1 , the chlorine atoms Cl(1) and Cl(2) connect the molecules via type II Cl ··· Cl contacts [ d (Cl ··· Cl) 3.377(1) Å, θ 1 = 171.9(1)°, θ 2 = 123.5(1)°; see Figure and Table ] to infinite helical strands extending parallel to the crystallographic b ‐axis. Interstrand association is accomplished by C–H ··· Cl hydrogen bonds [ d (H ··· Cl) 2.85–2.96 Å] resulting in the formation of a three‐dimensional supramolecular architecture.…”

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“…Moreover, the close distance of 3.134(2) Å between Br(2) and N(6) of adjacent molecules and the well defined bond geometry [∠C–Br ··· N 172.9(3)°] indicate the presence of a relatively strong Br ··· N interaction ( n ‐type halogen bond,, , Figure a, Figure b). The pattern of directed noncovalent bonding between the complex molecules is completed by a C–Br ··· π contact (π‐type halogen bond,, Figure c) with a Br ··· C pyrazole distance of 3.368(3) Å which is less than the sum of van der Waals radii of the respective atoms (3.55 Å).…”

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“…The other part of the solvent molecules, however, is linked to the host molecules with the participation of the chlorine atoms Cl4 A and Cl6 A via Cl•••O interactions. [20][21][22] The bond distances [d(Cl•••O) 3.03, 3.04 Å] are significantly smaller than the sum of the van der Waals radii (3.37 Å) of the atoms involved in this interaction, indicating a high bond strength.…”