Dimethyl­ammonium 3-carb­oxy­benzoate

Tausif Siddiqui; Vandavasi Koteswara Rao; Matthias Zeller; Sherri R Lovelace-Cameron

doi:10.1107/S160053681202096X

. 2012 May 19;68(Pt 6):o1778. doi: 10.1107/S160053681202096X

Dimethylammonium 3-carboxybenzoate

Tausif Siddiqui ^a, Vandavasi Koteswara Rao ^a, Matthias Zeller ^a, Sherri R Lovelace-Cameron ^a,^*

PMCID: PMC3379357 PMID: 22719555

Abstract

The asymmetric unit of the title organic salt, C₂H₈N⁺·C₈H₅O₄ ⁻, consists of two dimethylammonium cations and two 3-carboxybenzoate anions. The 3-carboxybenzoate anions are linked via strong intermolecular and nearly symmetrical O—H⋯O hydrogen bonds forming infinite chains parallel to [111]. Neighbouring chains are further connected by the dimethylammonium cations via N—H⋯O bonds, resulting in a double-chain-like structure. The dihedral angles of all carboxylate groups with respect to the phenylene rings are in the range 7.9 (1)–20.48 (9)°.

Related literature

For supramolecular structures comprising 3-carboxybenzoates, see: Guo et al. (2010 ▶); Liu et al. (2007 ▶); Weyna et al. (2009 ▶). For similar chain-like structures, see: Ballabh et al. (2005 ▶). For hydrolysis of formamides, see: Cottineau et al. (2011 ▶); Hine et al. (1981 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶). For hydrogen bonding, see: Gilli & Gilli (2009 ▶). graphic file with name e-68-o1778-scheme1.jpg

Experimental

Crystal data

C₂H₈N⁺·C₈H₅O₄ ⁻
M _r = 211.21
Triclinic,
a = 8.439 (5) Å
b = 10.133 (8) Å
c = 12.304 (9) Å
α = 91.858 (14)°
β = 94.599 (17)°
γ = 90.009 (14)°
V = 1048.2 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.32 × 0.21 × 0.09 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2011 ▶) T _min = 0.684, T _max = 0.746
13304 measured reflections
6417 independent reflections
4906 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.125
S = 1.06
6417 reflections
283 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: APEX2 (Bruker, 2011 ▶); cell refinement: SAINT (Bruker, 2011 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXLE (Hübschle et al., 2011 ▶) and SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681202096X/su2413sup1.cif

e-68-o1778-sup1.cif^{(21.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681202096X/su2413Isup2.hkl

e-68-o1778-Isup2.hkl^{(314KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681202096X/su2413Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O8	0.92	2.00	2.869 (2)	157
N1—H1B⋯O2ⁱ	0.92	1.84	2.744 (2)	166
N2—H2A⋯O4ⁱⁱ	0.92	1.93	2.822 (2)	164
N2—H2B⋯O6	0.92	1.88	2.784 (2)	166
O7—H3A⋯O3	1.18 (3)	1.26 (3)	2.4177 (19)	166 (3)
O7—H3A⋯O4	1.18 (3)	2.56 (3)	3.329 (2)	121.1 (18)
O5—H5A⋯O1ⁱⁱⁱ	1.18 (2)	1.27 (2)	2.4483 (19)	171 (2)
O5—H5A⋯O2ⁱⁱⁱ	1.18 (2)	2.66 (2)	3.462 (2)	124.2 (15)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We thank the Department of Energy (DOE) and the National Energy Technology Laboratory (NETL), USA, for financial support. The X-ray diffractometer was funded by National Science Foundation grant 0087210, Ohio Board of Regents grant CAP-491, and by Youngstown State University.

supplementary crystallographic information

Comment

The title compound, dimethylammonium 3-carboxybenzoate, was obtained as part of our investigations into the solvothermal synthesis of metal organic frameworks of magnesium with aromatic dicarboxylates. Reaction of magnesium nitrate with isophthalic acid and piperazine at 373 K did not yield an extended metal organic framework, but partial decomposition of the DMF solvent let to formation of the title dimethylammonium organic salt, which was isolated as a minor side product in the form of colourless plate-like crystals. Under the rather harsh solvothermal conditions used for the synthesis of many coordination compounds and metal organic frameworks formamides become unstable towards hydrolysis or Lewis acid catalyzed decarbonylation (Hine et al., 1981; Cottineau et al., 2011). This is also evidenced by the high number of dimethyl ammonium salts reported in the Cambridge Structural Database (CSD; Allen et al., 2002; 597 entries up to Feb. 2012), counting only structures that also contain at least one metal ion. With dimethyl amine itself being a gas and being used not extensively as a reagent, it can be safely assumed that most of these structures originated from in situ hydrolysis of a dimethyl amide such as DMF. Twenty eight of these entries in the CSD with dimethyl ammonium ions also contain formate ions, the other product of DMF hydrolysis. The title compound, the dimethylammonium salt of isophtalic acid, is one such example that incorporates ammonium cations formed in situ through decomposition of a formamide.

The asymmetric unit of the title compound is composed of two hydrogen-3-carboxybenzoate anions and two dimethyl ammonium cations (Fig. 1), which are connected with each other through an intricate network of N—H···O and O—H···O hydrogen bonds (Figs. 2–4). Details of the hydrogen bonding are given in Table 1. Individual 3-carboxybenzoate anions are monoprotonated, and are connected with each other through very strong and nearly symmetric O—H···O hydrogen bonds to form infinite chains parallel to the space diagonal of the unit cell (Fig. 2). Molecules in the chains are arranged in an ABAB···fashion, with crystallographically different monoanions alternating with each other. The O—H···O hydrogen bonds are characterized by nearly equidistant D—H and A—H distances (Table 1), as is typical for very strong hydrogen bonds with very electronegative donor and acceptor atoms (Gilli & Gilli, 2009). The keto oxygen atoms of the carboxylate units, which are not involved in the O—H···O hydrogen bonds, act as acceptors for N—H···O hydrogen bonds that originate from both of the dimethylammonium cations, which double bridge the carboxylic acid and carboxylate groups of the anions into a bis(dimethylammonium)—bis(COO^-···H⁺···^-OOC) cluster (Fig. 3). In such a manner parallel infinite 3-carboxybenzoate chains are connected into an inversion symmetric double chain like structure (Fig. 4).

Supramolecular structures comprising 3-carboxybenzoates have been reported previously (Guo et al., 2010; Liu et al., 2007; Weyna et al., 2009). Similar one-dimensional chain-like structures have been reported by (Ballabh et al., 2005).

Experimental

The compound was synthesized under solvothermal conditions. In a typical synthesis, Mg(NO₃)₂.6H₂O (0.064 g, 0.25 mmol) was dissolved in a 1:1 mixture of DMF (5.0 ml) and EtOH (5.0 ml). Then, alumina (Sorbent Technologies, Atlanta, GA) (0.051 g, 0.5 mmol), isophthalic acid (0.166 g, 1.0 mmol) and piperazine (0.043 g, 0.5 mmol) were added to the reaction mixture which was stirred for one hour before transferring the mixture into a glass vial. The final mixture was heated to 373 K for 48 h. The vial was then slowly cooled to room temperature. Slow cooling of the reaction mixture yielded colourless plate-like crystals of the title compound as a minor product.