X-ray crystal structures of [(Cy₂NH₂)]₃[C₆H₃(CO₂)₃]·4H₂O and [i-Bu₂NH₂][(Me₃ SnO₂C)₂C₆H₃CO₂]

Introduction

The multifunctional ligand derived by deprotonation of benzene-1,3,5-tricarboxylic acid has been widely used for the manufacture of microporous materials (Yaghi et al., 1996; Cheng et al., 2004). Thus, some solvated and nonsolvated benzene-1,3,5-tricarboxylato metal derivatives have been reported, for example, [(µ₄-benzene-1,3,5-tricarboxylato)-bis(methanol)-tris(trimethyltin(IV))] and [(µ₃-benzene-1,3,5-tricarboxylato)-tris(methanol-trimethyltin(IV))] (Ma et al., 2005), [(µ₃-benzene-1,3,5-tricarboxylato)-tris(dimethylsulfoxide-trimethyltin(IV))] dimethylsulfoxide solvate (Dakternieks et al., 2002), [(µ₃-benzene-1,3,5-tricarboxylato)-tris(tribenzyltin(IV))] and [(µ₃-benzene-1,3,5-tricarboxylato)-tris(triphenyltin(IV))] ethanol solvate dihydrate (Ma et al., 2005), [(µ₃-benzene-1,3,5-tricarboxylato)-tris(triphenyltin(IV))] dichloromethane diethylether solvate (Ma et al., 2005) and catena [(µ₃-benzene-1,3,5-tricarboxylato)-bis(trimethyltin(IV))] monohydrate (Ma et al., 2005).

The chemistry of organotin (IV) derivatives is still the subject of many studies linked to various applications in the areas of medicine, industry, and agriculture (Ayrey and Poller, 1980; Owen, 1980; Blunden et al., 1984; Gielen, 1985; Crowe, 1994; Gielen et al., 1995). With this aim, several supramolecular organotin compounds have been synthesized and characterized (Chandrasekhar et al., 2003; Kapoor et al., 2005; Herntrich and Merzweiler, 2006). In our laboratory, some of them containing SnMe₃ and SnPh₃ residues have been recently published (Diop et al., 2011, 2012; Sow et al., 2012a,b). In this context, we have recently published a supramolecular trimethyltin(IV) triscarboxylate [Cy₂NH₂]₂[1-Me₃(H₂O)SnOCO-3,5-(OOC)₂C₆H₃]·EtOH (Ndoye et al., 2012). Thus, in a continuation of these works, we have initiated here the study of the interactions between both 1,3,5-(HOOC)₃C₆H₃ and Cy₂NH and between [i-Bu₂NH₂]₃[1,3,5-(OOC)₃C₆H₃] and SnMe₃Cl, which have yielded the title derivatives for which X-ray structures have been determined.

Results and discussion

The structure of 1 consists of a three-dimensional (3D) network involving intra- and intermolecular hydrogen bonds (Figure 1). Every tricarboxylate anion is surrounded by three dicyclohexyl ammonium cations involving N₁, N₂ and N₃. The N₁- and N₃-containing cations are involved in eight-membered ring formation, whereas that based on the N₂-containing cation forms a 12-membered ring. A fourth 12-membered ring involving two water molecules (containing O₈ and O₉) and two carboxylic acid groups (containing C₇ and C₈) and a fifth 14-membered ring involving three water molecules (containing O₇, O₈ and O₉) and two carboxylic acids (containing C₈ and C₉) complete the hydrogen bond network. Two cations (containing N₁ and N₂) are hydrogen-bonded to a carboxylic acid and a water molecule while the cation (containing N₃) hydrogen bonds to two carboxylic acid groups. The water molecules are also involved in a diverse network of hydrogen bonds, with only the water molecule (containing O₇) not forming the maximum of three such interactions. Thus, the water molecule (containing O₇) only hydrogen bonds to one other water molecule (containing O₈) and one carboxylic acid moiety (containing C₉), and not at all as H-bond receptor. The O₈ atom links to two water molecules and one carboxylic acid moiety, while the water molecule (containing O₉) H-bonds to two carboxylic acids (containing C₇ and C₈) and one water molecule (containing O₈). The water molecule (containing O₁₀) links with two carboxylic acid groups (containing C₈ and C₉) and one cation (containing N₂). The overall network is a reticular grid (Figure 2); the relevant geometric data relating to these hydrogen bonds are given in Table 1.

Figure 1

The asymmetric unit of compound 1.

Selected bond distances (Å): O(1)-C(7): 1.2482(18); O(2)-C(7): 1.2635(18); O(3)-C(8): 1.2647(18); O(4)-C(8): 1.2543(19); O(5)-C(9): 1.2307(19); O(6)-C(9): 1.273(2); angles (°): O(1)-C(7)-O(2): 123.98(14); O(4)-C(8)-O(3): 123.73(14); O(5)-C(9)-O(6): 124.54(14). Symmetry operations: (′) 1-x, 1/2+y, 3/2-z; (″) 3/2-x, 2-y, 1/2+z; (′″) -x, y-1/2, 3/2-z.

Figure 2

3D structure of compound 1.

In 2, each of the two tin atoms is five-coordinated by two carboxylate oxygen atoms derived from the triscarboxylate ligand, which are in apical positions, and to three methyl groups occupying the equatorial positions of a trigonal bipyramid (Figure 3). There are two types of carboxylate groups in the structure: one which is bidentate involving C₇ and two monodentate carboxylates based on C₈ and C₉. There are two types of tin centers with a trigonal bipyramidal environment in the molecule, although they have similar geometries but different O-Sn-O angles – O₁-Sn₁-O_5′ [170.82°(6)] and O₃-Sn₂-O_2″ [172.26°(6)] angles show that the O-Sn-O frameworks deviate from linearity. The almost planar SnMe₃ skeletons [ΣC-Sn₁-C angles: 359.82, 358.98°] are bridged by the carboxylate O atoms, leading to a layered structure. Thus, the layered structure is composed of tetranuclear rings in which the noncoordinated carboxylate O atoms (O₄ and O₆) are involved in hydrogen bonds with NH₂ groups of i-Bu₂NH₂⁺ cations, which lie within these macrocycles [H_1A…O₆, 1.784 Å; H_1B…O₄, 1.862 Å], offset from their centers to allow bonding to the two carboylate groups at one corner (Figure 4). The Sn-O bond lengths between the bridging ligand and the tin centers [2.2322(15), 2.2975(15), 2.4046(16), and 2.1670(16) Å, respectively, for Sn₁-O₁, Sn₁-O_5′, Sn₂-O₂, and Sn₂-O_3″] are in the range of reported Sn-O distances (Diassé-Sarr et al., 2004; Alvarez Boo et al., 2006). The structure of [(Me₃SnO₂C)₂C₆H₃CO₂] [i-Bu₂NH₂] (2) can be compared with the related species (Me₃SnO₂C)₂C₆H₃CO₂H·H₂O (Ma et al., 2005). Although the framework formed by the [1,3-(Me₃SnO₂C)₂-6-(OOC)C₆H₃]^- anion is similar in both cases, the remaining countercations [i-Bu₂NH₂]⁺ or [H₃O]⁺ impart quite different lattice structures. Thus, while [i-Bu₂NH₂]⁺ hydrogen bonds to two carboxylate groups within the same plane, generating layers independent of each other, the [H₃O]⁺ species forms hydrogen bonds between layers, generating a 3D structure.

Figure 3

The asymmetric unit of compound 2; only the major component of the disordered cation is shown for clarity.

Selected bond distances (Å): Sn(1)-O(1): 2.2322(15); Sn(1)-O(5′): 2.2975(15), Sn(2)-O(3) 2.1670(16), Sn(2)-O(2″) 2.4046(16), O(1)-C(7): 1.273(3); O(2)-C(7): 1.242(3); O(3)-C(9): 1.280(3): O(4)-C(9): 1.242(3); O(5)-C(8): 1.266(3); O(6)-C(8): 1.249(3); angles (°): C(11)-Sn(1)-C(12) 125.20(14), C(11)-Sn(1)-C(10) 115.75(18), C(12)-Sn(1)-C(10), 118.87(19), C(11)-Sn(1)-O(1) 96.64(9), C(12)-Sn(1)-O(1): 90.70(9), C(10)-Sn(1)-O(1) 86.52(10), C(11)-Sn(1)-O(5′) 91.25(8), C(12)-Sn(1)-O(5′) 88.58(9), C(10)-Sn(1)-O(5′) 85.82(10), O(1)-Sn(1)-O(5′) 170.82(6), C(14)-Sn(2)-C(15) 117.14(15), C(14)-Sn(2)-C(13) 116.75(15), C(15)-Sn(2)-C(13) 125.09(12), C(14)-Sn(2)-O(3) 87.13(9), C(15)-Sn(2)-O(3) 97.65(9), C(13)-Sn(2)-O(3) 94.68(9), C(14)-Sn(2)-O(2″) 85.13(9), C(15)-Sn(2)-O(2″) 86.16(9), C(13)-Sn(2)-O(2″) 88.56(9), O(3)-Sn(2)-O(2″) 172.26(6). Symmetry operations: (′) x-1, y, z; (″) -x+1/2, y-1/2, (′″) 1+x, y, z.

Figure 4

Lattice structure of compound 2.

The isobutyl groups on nitrogen have been omitted for clarity.

Experimental

All chemicals were purchased from Aldrich (Germany) and used without any further purification. The following abbreviations are used: vs (very strong), s (strong), m (medium), sh (shoulder), br (broad).