Crystal structure of trans-bis­(di­ethano­lamine-κ³ O,N,O′)manganese(II) bis­(3-amino­benzoate)

The title salt, [Mn(C₄H₁₁NO₂)₂](C₇H₆NO₂)₂, contains a centrosymmetric cation with the Mn²⁺ ion coordinated octa­hedrally by two tridentate di­ethano­lamine (DEA) ligands. The cations are connected to the anions through O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network structure.

Abstract

Reaction of m-amino­benzoic acid (MABA), di­ethano­lamine (DEA) and MnCl₂·4H₂O led to the formation of the title salt, [Mn(C₄H₁₁NO₂)₂](C₇H₆NO₂)₂. In the complex cation, the Mn²⁺ ion is located on an inversion centre and is coordinated by two symmetry-related tridentate DEA mol­ecules, leading to the formation of a slightly distorted MnN₂O₄ octa­hedron. The MABA⁻ counter-anions are connected to the complex ion by a pair of rather strong O—H⋯O hydrogen bonds, yielding a 1:2 supra­molecular aggregate. Much weaker N—H⋯O hydrogen bonds connect neighbouring aggregates into a three-dimensional network structure.

Chemical context  

In contrast to the two other isomers of amino­benzoic acid, viz. p-amino­benzoic acid (or vitamin B₁₀) and o-amino­benzoic acid (or antranylic acid), m-amino­benzoic acid (3-amino­benzoic acid or MABA) is not biologically active. Nevertheless, we are studying this substance within the context of mixed-ligand coordination complex formation including benzoic acid isomers and ethano­lamines (Ashurov et al., 2015 ▸). As a result of the presence of two spatially separated electron-donor functional groups in the MABA mol­ecule, the reported metal complexes of this ligand are mostly coordination polymers. Polymerization may take place involving both COOH and NH₂ functional groups (Wang et al., 2004 ▸; Flemig et al., 2008 ▸; Tan et al., 2006 ▸; Wei et al., 2006 ▸; Shen & Lush, 2010 ▸; Wang et al., 2006 ▸;), or only one of them: COOH (Kozioł et al., 1992 ▸; Murugavel & Banerjee, 2003 ▸; Flemig et al., 2008 ▸; Tsaryuk et al., 2014 ▸) or, more infrequently, NH₂ (Wang et al., 2004 ▸).

In discrete monoligand complexes, the MABA mol­ecules coordinate to metal ions only bidentately through the oxygen atoms of the carb­oxy­lic group (Ozhafarov et al., 1981 ▸) while in mixed-ligand complexes, the carb­oxy­lic group can feature mono- (Sundberg et al., 1998 ▸;) or bidentate (Palanisami et al., 2013 ▸) coordination modes. Coordination through the nitro­gen atom is observed only in an Ag complex with participation of the co-ligand p-toluene­sulfonate (Smith et al., 1998 ▸).

The disposition of MABA mol­ecules as non-coordinating counter-ions (in their benzoate form) is characteristic for mixed-ligand Mn (Fang & Nie, 2011 ▸) or Cd complexes (Gao et al., 2011 ▸) with 4,4-bi­pyridine as co-ligand whereas the simultaneous presence of coordinating and non-coordinating MABA species was reported for an Mn complex with 1,10-phenanthroline as an additional ligand (Zhang, 2006 ▸).

Di­ethano­lamine (DEA) ligands can coordinate to metal ions in a mono- (Petrović et al., 2006 ▸), bi- (Yilmaz et al., 2000 ▸) or tridenentate (Buvaylo et al., 2009 ▸) mode if two ligand mol­ecules are situated around the central atom. However, a combination of these modes, for example, in a bi- and tridentate fashion, is also possible (Bertrand et al., 1979 ▸).

A search in the Cambridge Structural Database (CSD; Groom & Allen, 2014 ▸) revealed that crystal structures have been reported for complexes of MABA and DEA with many metal ions, including zinc, copper, nickel, manganese, cadmium, cobalt, etc. However, no mixed-ligand metal complex including MABA and DEA is documented in the CSD. In order to prepare such compounds, we carried out a synthesis in a solution containing an Mn salt, MABA and DEA. Instead of the desired complex, the title salt, [Mn(C₄H₁₁NO₂)₂](C₇H₆NO₂)₂, consisting of discrete [Mn(DEA)₂]²⁺ cations and MABA⁻ anions was obtained.

Structural commentary  

The asymmetric unit consists of one DEA ligand, one MABA⁻ anion and one Mn²⁺-ion, the latter being located on an inversion centre (Fig. 1 ▸). Coordination of the DEA ligand to the metal ion takes place in a tridentate O,N,O′ mode. The Mn—ligand bond lengths cover a range from 2.065 (2) to 2.096 (2) Å with an angular range of 81.79 (10) to 98.21 (10)°, leading to a slightly distorted MnN₂O₄ octa­hedron. Since the DEA ligands are in their neutral form, a charged component in the outer sphere is required for charge compensation. Hence, two MABA⁻ anions in the benzoate form are present per complex ion. The carboxyl­ate group of the anionic mol­ecule is tilted by 14.4 (4)° relative to the aromatic ring.

Figure 1.

The structures of the mol­ecular moieties in the title salt. Displacement ellipsoids are drawn at the 50% probability level and the asymmetric unit is identified by the numbering of its atoms.

Supra­molecular features  

The MABA⁻ anion is connected to the complex ion by a pair of rather strong O—H⋯O hydrogen bonds involving the DEA hy­droxy groups [2.562 (3) and 2.611 (3) Å; Table 1 ▸], which give rise to the formation of a supra­molecular motif with graph-set notation (8). The resulting supra­molecular cationic:anionic 1:2 units are associated to other such units by relatively weak N—H⋯O hydrogen bonds [2.965 (4) and 3.008 (4) Å; Table 1 ▸] involving the secondary amine function of the DEA ligand and one of the H atoms of the MABA⁻ amino group; notably, the second H atom (H1B) of the amino group remains without an acceptor. These four hydrogen bonds associate the different moieties into a three-dimensional network (Fig. 2 ▸).

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O2i	0.96 (3)	2.19 (3)	2.965 (4)	137 (3)
N1—H1A⋯O1ii	0.97 (2)	2.05 (2)	3.008 (4)	170 (5)
O4—H4⋯O2iii	0.99 (5)	1.63 (5)	2.611 (3)	169 (4)
O3—H3⋯O1	0.92 (6)	1.65 (6)	2.562 (3)	173 (5)

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

Figure 2.

The crystal packing in the title structure. Hydrogen bonds are shown as dashed lines.

Synthesis and crystallization  

To an aqueous solution (5 ml) of MnCl₂·4H₂O (0.098 g, 0.5 mmol) was slowly added an ethano­lic solution (5 ml) containing DEA (96 µl) and MABA (0.137 g, 1 mmol) under constant stirring. A light-pink crystalline product was obtained at room temperature by solvent evaporation after 20 days.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The positions of the O- and N-bound hydrogen atoms were located from difference Fourier maps. Whereas O-bound hydrogen atoms were refined freely, N-bound H atoms were refined with soft distance restraints of 0.98 Å for the secondary amine function and of 0.95 Å for the primary amine function. The C-bound hydrogen atoms were placed in calculated positions and refined as riding atoms with C—H = 0.93 and 0.97 Å for aromatic and methyl­ene hydrogen atoms, respectively, and with U _iso(H) = 1.2U _eq(C).

Table 2. Experimental details.

Crystal data
Chemical formula	[Mn(C4H11NO2)2](C7H6NO2)2
M r	537.47
Crystal system, space group	Orthorhombic, P b c a
Temperature (K)	293
a, b, c (Å)	10.6120 (4), 10.8219 (4), 21.7591 (8)
V (Å3)	2498.86 (15)
Z	4
Radiation type	Cu Kα
μ (mm−1)	4.76
Crystal size (mm)	0.32 × 0.20 × 0.18
Data collection
Diffractometer	Oxford Diffraction Xcalibur Ruby
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▸)
T min, T max	0.932, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	10631, 2589, 1740
R int	0.056
(sin θ/λ)max (Å−1)	0.630
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.045, 0.136, 1.06
No. of reflections	2589
No. of parameters	180
No. of restraints	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.37, −0.22

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009 ▸), SHELXS97, XP and SHELXTL (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸) and Mercury (Macrae et al., 2006 ▸).

Supplementary Material

CCDC reference: 1463701

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Crystal data

[Mn(C4H11NO2)2](C7H6NO2)2	Dx = 1.429 Mg m−3
Mr = 537.47	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, Pbca	Cell parameters from 1995 reflections
a = 10.6120 (4) Å	θ = 4.1–75.0°
b = 10.8219 (4) Å	µ = 4.76 mm−1
c = 21.7591 (8) Å	T = 293 K
V = 2498.86 (15) Å3	Block, pink
Z = 4	0.32 × 0.20 × 0.18 mm
F(000) = 1132

Data collection

Oxford Diffraction Xcalibur Ruby diffractometer	2589 independent reflections
Radiation source: fine-focus sealed X-ray tube	1740 reflections with I > 2σ(I)
Detector resolution: 10.2576 pixels mm-1	Rint = 0.056
ω scans	θmax = 76.3°, θmin = 4.1°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	h = −13→11
Tmin = 0.932, Tmax = 1.000	k = −10→13
10631 measured reflections	l = −23→27

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.045	Hydrogen site location: mixed
wR(F2) = 0.136	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ2(Fo2) + (0.0511P)2 + 0.8708P] where P = (Fo2 + 2Fc2)/3
2589 reflections	(Δ/σ)max < 0.001
180 parameters	Δρmax = 0.37 e Å−3
3 restraints	Δρmin = −0.22 e Å−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Mn1	0.5000	0.5000	0.5000	0.04895 (19)
O4	0.3260 (2)	0.5819 (2)	0.52055 (10)	0.0539 (5)
O3	0.5434 (2)	0.4939 (2)	0.59247 (10)	0.0565 (5)
O1	0.7755 (2)	0.5192 (2)	0.62224 (11)	0.0632 (6)
O2	0.8300 (3)	0.3560 (3)	0.56693 (12)	0.0734 (7)
N2	0.4066 (3)	0.3381 (2)	0.52171 (12)	0.0512 (6)
C1	0.9619 (3)	0.4152 (3)	0.64986 (13)	0.0518 (7)
C2	0.9990 (3)	0.5096 (3)	0.68864 (13)	0.0516 (6)
H2A	0.9520	0.5821	0.6899	0.062*
N1	1.1449 (4)	0.5979 (4)	0.76146 (16)	0.0793 (10)
C7	0.8479 (3)	0.4310 (3)	0.60979 (14)	0.0547 (7)
C3	1.1051 (3)	0.4986 (4)	0.72582 (13)	0.0566 (7)
C6	1.0307 (3)	0.3059 (4)	0.64803 (16)	0.0617 (8)
H6	1.0069	0.2422	0.6218	0.074*
C4	1.1723 (3)	0.3888 (4)	0.72398 (15)	0.0659 (9)
H4A	1.2432	0.3795	0.7487	0.079*
C11	0.2710 (3)	0.3669 (3)	0.53064 (17)	0.0618 (8)
H11A	0.2348	0.3081	0.5592	0.074*
H11B	0.2272	0.3586	0.4917	0.074*
C5	1.1356 (3)	0.2928 (4)	0.68595 (16)	0.0682 (9)
H5	1.1811	0.2193	0.6857	0.082*
C10	0.2524 (4)	0.4967 (3)	0.55517 (17)	0.0657 (9)
H10A	0.1640	0.5191	0.5525	0.079*
H10B	0.2772	0.4999	0.5980	0.079*
C9	0.4717 (4)	0.2849 (3)	0.57585 (18)	0.0690 (10)
H9A	0.5494	0.2457	0.5628	0.083*
H9B	0.4187	0.2222	0.5944	0.083*
C8	0.5008 (4)	0.3832 (4)	0.62248 (16)	0.0724 (10)
H8A	0.4259	0.4010	0.6464	0.087*
H8B	0.5656	0.3537	0.6503	0.087*
H4	0.276 (5)	0.606 (5)	0.484 (2)	0.099 (15)*
H2	0.429 (4)	0.278 (3)	0.4912 (14)	0.071 (11)*
H3	0.628 (6)	0.501 (5)	0.600 (3)	0.109 (18)*
H1A	1.196 (5)	0.571 (6)	0.7962 (18)	0.13 (2)*
H1B	1.087 (6)	0.664 (5)	0.771 (3)	0.18 (3)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Mn1	0.0487 (3)	0.0479 (3)	0.0503 (3)	−0.0033 (3)	−0.0032 (3)	−0.0027 (3)
O4	0.0536 (11)	0.0496 (11)	0.0586 (12)	0.0035 (10)	−0.0011 (10)	−0.0037 (10)
O3	0.0553 (12)	0.0658 (14)	0.0485 (10)	−0.0038 (11)	−0.0093 (9)	−0.0029 (11)
O1	0.0529 (12)	0.0758 (16)	0.0608 (12)	0.0082 (11)	−0.0109 (10)	−0.0144 (12)
O2	0.0762 (16)	0.0790 (17)	0.0650 (14)	0.0167 (14)	−0.0226 (12)	−0.0215 (13)
N2	0.0540 (14)	0.0457 (13)	0.0539 (13)	−0.0065 (11)	0.0018 (11)	−0.0061 (11)
C1	0.0494 (15)	0.0631 (18)	0.0429 (13)	−0.0042 (14)	0.0023 (12)	0.0026 (14)
C2	0.0465 (14)	0.0632 (17)	0.0452 (13)	−0.0017 (14)	0.0025 (11)	0.0061 (14)
N1	0.077 (2)	0.094 (3)	0.0674 (19)	−0.014 (2)	−0.0126 (16)	−0.0015 (19)
C7	0.0504 (16)	0.064 (2)	0.0496 (16)	−0.0016 (15)	−0.0012 (12)	−0.0024 (14)
C3	0.0520 (16)	0.073 (2)	0.0448 (13)	−0.0117 (16)	0.0003 (12)	0.0032 (16)
C6	0.067 (2)	0.065 (2)	0.0535 (16)	0.0017 (17)	−0.0015 (14)	−0.0011 (16)
C4	0.0520 (17)	0.094 (3)	0.0522 (17)	0.0043 (19)	−0.0040 (14)	0.0079 (18)
C11	0.0559 (19)	0.0569 (18)	0.073 (2)	−0.0107 (15)	0.0060 (15)	−0.0005 (16)
C5	0.063 (2)	0.079 (2)	0.0622 (19)	0.0150 (18)	−0.0014 (15)	0.0056 (18)
C10	0.0606 (19)	0.066 (2)	0.071 (2)	0.0055 (18)	0.0172 (16)	0.0018 (19)
C9	0.077 (2)	0.0563 (19)	0.074 (2)	−0.0046 (17)	−0.0092 (18)	0.0154 (17)
C8	0.076 (2)	0.088 (3)	0.0533 (18)	−0.014 (2)	−0.0086 (17)	0.0136 (19)

Geometric parameters (Å, º)

Mn1—O3i	2.065 (2)	N1—C3	1.391 (5)
Mn1—O3	2.065 (2)	N1—H1A	0.97 (2)
Mn1—N2	2.067 (3)	N1—H1B	0.97 (2)
Mn1—N2i	2.068 (3)	C3—C4	1.387 (5)
Mn1—O4	2.096 (2)	C6—C5	1.393 (5)
Mn1—O4i	2.096 (2)	C6—H6	0.9300
O4—C10	1.424 (4)	C4—C5	1.384 (6)
O4—H4	0.99 (5)	C4—H4A	0.9300
O3—C8	1.438 (4)	C11—C10	1.515 (5)
O3—H3	0.92 (6)	C11—H11A	0.9700
O1—C7	1.255 (4)	C11—H11B	0.9700
O2—C7	1.251 (4)	C5—H5	0.9300
N2—C9	1.482 (4)	C10—H10A	0.9700
N2—C11	1.485 (4)	C10—H10B	0.9700
N2—H2	0.959 (19)	C9—C8	1.502 (5)
C1—C2	1.383 (5)	C9—H9A	0.9700
C1—C6	1.390 (5)	C9—H9B	0.9700
C1—C7	1.501 (4)	C8—H8A	0.9700
C2—C3	1.391 (4)	C8—H8B	0.9700
C2—H2A	0.9300
O3i—Mn1—O3	180.00 (14)	O1—C7—C1	117.0 (3)
O3i—Mn1—N2	98.21 (10)	C4—C3—N1	121.5 (3)
O3—Mn1—N2	81.79 (10)	C4—C3—C2	118.2 (3)
O3i—Mn1—N2i	81.79 (10)	N1—C3—C2	120.3 (4)
O3—Mn1—N2i	98.21 (10)	C1—C6—C5	119.3 (4)
N2—Mn1—N2i	180.0	C1—C6—H6	120.4
O3i—Mn1—O4	89.88 (9)	C5—C6—H6	120.4
O3—Mn1—O4	90.12 (9)	C5—C4—C3	121.1 (3)
N2—Mn1—O4	83.54 (10)	C5—C4—H4A	119.5
N2i—Mn1—O4	96.46 (10)	C3—C4—H4A	119.5
O3i—Mn1—O4i	90.11 (9)	N2—C11—C10	111.6 (3)
O3—Mn1—O4i	89.89 (9)	N2—C11—H11A	109.3
N2—Mn1—O4i	96.47 (10)	C10—C11—H11A	109.3
N2i—Mn1—O4i	83.53 (10)	N2—C11—H11B	109.3
O4—Mn1—O4i	180.0	C10—C11—H11B	109.3
C10—O4—Mn1	108.80 (19)	H11A—C11—H11B	108.0
C10—O4—H4	107 (3)	C4—C5—C6	120.2 (4)
Mn1—O4—H4	115 (3)	C4—C5—H5	119.9
C8—O3—Mn1	113.5 (2)	C6—C5—H5	119.9
C8—O3—H3	108 (3)	O4—C10—C11	110.0 (3)
Mn1—O3—H3	113 (4)	O4—C10—H10A	109.7
C9—N2—C11	115.4 (3)	C11—C10—H10A	109.7
C9—N2—Mn1	106.7 (2)	O4—C10—H10B	109.7
C11—N2—Mn1	108.5 (2)	C11—C10—H10B	109.7
C9—N2—H2	100 (2)	H10A—C10—H10B	108.2
C11—N2—H2	118 (3)	N2—C9—C8	110.9 (3)
Mn1—N2—H2	108 (2)	N2—C9—H9A	109.4
C2—C1—C6	119.8 (3)	C8—C9—H9A	109.4
C2—C1—C7	120.0 (3)	N2—C9—H9B	109.4
C6—C1—C7	120.2 (3)	C8—C9—H9B	109.4
C1—C2—C3	121.5 (3)	H9A—C9—H9B	108.0
C1—C2—H2A	119.3	O3—C8—C9	110.4 (3)
C3—C2—H2A	119.3	O3—C8—H8A	109.6
C3—N1—H1A	112 (4)	C9—C8—H8A	109.6
C3—N1—H1B	119 (5)	O3—C8—H8B	109.6
H1A—N1—H1B	114 (5)	C9—C8—H8B	109.6
O2—C7—O1	124.2 (3)	H8A—C8—H8B	108.1
O2—C7—C1	118.8 (3)
C6—C1—C2—C3	0.7 (5)	C2—C3—C4—C5	0.4 (5)
C7—C1—C2—C3	−179.2 (3)	C9—N2—C11—C10	88.9 (4)
C2—C1—C7—O2	166.2 (3)	Mn1—N2—C11—C10	−30.7 (3)
C6—C1—C7—O2	−13.6 (5)	C3—C4—C5—C6	0.9 (6)
C2—C1—C7—O1	−14.4 (5)	C1—C6—C5—C4	−1.4 (5)
C6—C1—C7—O1	165.7 (3)	Mn1—O4—C10—C11	−38.9 (3)
C1—C2—C3—C4	−1.2 (5)	N2—C11—C10—O4	47.5 (4)
C1—C2—C3—N1	175.9 (3)	C11—N2—C9—C8	−76.9 (4)
C2—C1—C6—C5	0.7 (5)	Mn1—N2—C9—C8	43.7 (4)
C7—C1—C6—C5	−179.5 (3)	Mn1—O3—C8—C9	17.4 (4)
N1—C3—C4—C5	−176.6 (3)	N2—C9—C8—O3	−40.8 (4)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O2ii	0.96 (3)	2.19 (3)	2.965 (4)	137 (3)
N1—H1A···O1iii	0.97 (2)	2.05 (2)	3.008 (4)	170 (5)
O4—H4···O2i	0.99 (5)	1.63 (5)	2.611 (3)	169 (4)
O3—H3···O1	0.92 (6)	1.65 (6)	2.562 (3)	173 (5)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1/2, −y+1/2, −z+1; (iii) x+1/2, y, −z+3/2.