Hexa­aqua­manganese(II) 3-carboxy-4-hydroxy­benzene­sulfonate dihydrate

In the title compound, [Mn(H₂O)₆]L₂·2H₂O, where HL is 3-carboxy-4-hydroxy­benzene­sulfonic acid (C₇H₆O₆S), each Mn^II cation lies on an inversion center and is octahedrally coordinated by six water mol­ecules. The L^- anions do not coordinate to manganese, but act as counter-anions. The crystal structure is composed of alternating layers of [Mn(H₂O)₆]²⁺ cations and sulfonate anions. The [Mn(H₂O)₆]²⁺ cations, water mol­ecules and L^- anions are connected through a complex pattern of H-bonding interactions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.031
• wR factor = 0.089
• Data-to-parameter ratio = 12.3

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S1. Comment

Metal phosphonate chemistry has been developed rapidly. By constrast, the coordination chemistry of transition metal sulfonates is not well explored or rationalized, owing to the preconception that sulfonates are weakly coordinating ligands (Yu et al., 2001). In some cases, a sulfonate group can compete with water molecules in coordinating to a metal ion (Shimizu et al., 1998; Smith et al., 1998; Sundberg & Sillanpaa, 1993). Squattrito and co-workers have studied the structures of some transition metal sulfonates, in which the metal is coordinated by water molecules, the sulfonate anions remaining uncoordinated (Gunderman et al., 1997; Kosnic et al., 1992; Shubnell et al., 1994). We have determined the crystal structures of five transition metal (Mn, Co, Ni, Cu and Zn) 3-carboxy-4-hydroxybenzenesulfonates. The crystal structure of the manganese compound, (I), is presented here, and the crystal structures of the other four related compounds are reported in the following papers.

The Mn atom is located on an inversion center, and all other atoms are in general positions. Selected bond lengths and angles are given in Table 1. Fig. 1 shows the asymmetric unit, together with the complete coordination environment of the Mn^II cation. Each Mn^II cation is coordinated by six water molecules, giving an octahedral coordination geometry. The average Mn—O distance of 2.173 Å is similar to values in other manganese compounds (Wu et al., 1995). Owing to the weak coordinating ability of sulfonate ions toward transition metal ions, the sulfonate ions are non-coordinating. The crystal structure of (I) is composed of alternating layers of [Mn(H₂O)₆]²⁺ cations and sulfonate anions, as shown in Fig. 2. Within the sulfonate layer, there are rows of anions with alternating orientations of the organic group.

There is one additional uncoordinated water molecule in the asymmetric unit. The [Mn(H₂O)₆]²⁺ cations, water molecules and L⁻ anions are connected through a complex pattern of hydrogen-bonding interactions. Selected hydrogen-bond parameters are listed in Table 2. There are 10 H atoms available for hydrogen bonding in the asymmetric unit. Some of the water molecules play a role as both acceptor and donor, while the hydroxyl and carboxyl OH groups are only donors, and the sulfonate and carboxyl O atoms are necessarily only acceptors.

S2. Experimental

A mixture of 3-carboxy-4-hydroxybenzenesulfonic acid (0.44 g, 2 mmol) and MnCO₃ (0.12 g, 1 mmol) in water (10 ml) was stirred at room temperature for 30 min. Colorless crystals of compound (I) were obtained after leaving the solution to stand at room temperature for several days. Analysis calculated for C₁₄H₂₆MnO₂₀S₂: C 26.55, H 4.14%; found: C 26.62, H 4.18%.

S3. Refinement

All H atoms on C atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C). The H atoms of the carboxyl group and hydroxyl group were also positioned geometrically and refined as riding atoms, with O—H = 0.82 Å and U_iso(H) = 1.5U_eq(O). The water H atoms were located in a difference Fourier map and refined with U_iso(H) = 1.5U_eq(O).

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97; molecular graphics: SHELXTL-Plus (Sheldrick, 1990); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. View of the asymmetric unit, expanded to show the complete coordination of Mn^II, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. View of the alternating layers of cations and anions, along the a axis.

(I)

Crystal data

[Mn(H2O)6](C7H5O6S)2·2H2O	Z = 1
Mr = 633.41	F(000) = 327
Triclinic, P1	Dx = 1.723 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.0608 (19) Å	Cell parameters from 19 reflections
b = 7.1535 (19) Å	θ = 5.5–9.9°
c = 13.836 (3) Å	µ = 0.81 mm^−1
α = 90.49 (2)°	T = 293 K
β = 90.49 (2)°	Block, colorless
γ = 119.118 (17)°	0.50 × 0.32 × 0.28 mm
V = 610.4 (3) Å^3

Data collection

Siemens P4 diffractometer	1961 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 26.0°, θmin = 2.9°
ω scans	h = −1→8
Absorption correction: ψ scan (North et al., 1968)	k = −8→8
Tmin = 0.645, Tmax = 0.798	l = −17→17
3086 measured reflections	3 standard reflections every 97 reflections
2384 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.089	w = 1/[σ^2(Fo^2) + (0.0508P)^2 + 0.0568P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.001
2384 reflections	Δρmax = 0.26 e Å^−3
194 parameters	Δρmin = −0.31 e Å^−3
8 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.264 (10)

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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
C1	0.8900 (3)	0.1678 (3)	0.17333 (15)	0.0268 (5)
C2	0.8119 (3)	0.1904 (3)	0.08565 (15)	0.0263 (4)
H2	0.6714	0.1695	0.0808	0.032*
C3	0.9400 (3)	0.2443 (3)	0.00381 (15)	0.0261 (5)
C4	1.1539 (4)	0.2807 (4)	0.01224 (17)	0.0312 (5)
C5	1.2324 (4)	0.2598 (4)	0.10198 (18)	0.0362 (5)
H5	1.3741	0.2849	0.1079	0.043*
C6	1.1023 (4)	0.2026 (4)	0.18168 (17)	0.0330 (5)
H6	1.1553	0.1871	0.2411	0.040*
C7	0.8519 (4)	0.2561 (3)	−0.09135 (15)	0.0292 (5)
O1	0.8419 (3)	0.1192 (3)	0.35883 (12)	0.0451 (5)
O2	0.5700 (3)	−0.1536 (2)	0.25555 (11)	0.0332 (4)
O3	0.5851 (3)	0.1886 (3)	0.26742 (13)	0.0430 (4)
O4	0.6524 (3)	0.2231 (3)	−0.08789 (12)	0.0392 (4)
H4	0.6110	0.2315	−0.1424	0.059*
O5	0.9526 (3)	0.2908 (3)	−0.16613 (12)	0.0417 (4)
O6	1.2851 (3)	0.3311 (3)	−0.06414 (13)	0.0465 (5)
H6A	1.2210	0.3380	−0.1125	0.070*
OW1	0.3545 (4)	0.1569 (3)	0.48723 (13)	0.0485 (5)
OW2	0.7916 (3)	0.5192 (3)	0.55984 (15)	0.0488 (5)
OW3	0.6469 (3)	0.5564 (3)	0.35531 (12)	0.0369 (4)
OW4	0.8706 (3)	0.2019 (3)	0.63169 (13)	0.0419 (4)
S1	0.71093 (9)	0.07782 (8)	0.27139 (4)	0.02835 (18)
Mn1	0.5000	0.5000	0.5000	0.02785 (18)
H1A	0.301 (4)	0.065 (4)	0.4383 (16)	0.042*
H1B	0.286 (4)	0.073 (4)	0.5367 (16)	0.042*
H2A	0.818 (4)	0.418 (4)	0.579 (2)	0.042*
H2B	0.902 (4)	0.631 (4)	0.5872 (19)	0.042*
H3A	0.636 (4)	0.449 (4)	0.3207 (18)	0.042*
H3B	0.614 (4)	0.634 (4)	0.3169 (18)	0.042*
H4A	0.857 (4)	0.210 (4)	0.6940 (13)	0.042*
H4B	1.010 (3)	0.274 (4)	0.625 (2)	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0317 (11)	0.0233 (10)	0.0239 (10)	0.0123 (9)	−0.0017 (9)	0.0007 (8)
C2	0.0253 (10)	0.0246 (10)	0.0267 (10)	0.0104 (8)	0.0001 (8)	0.0014 (8)
C3	0.0296 (11)	0.0204 (10)	0.0252 (10)	0.0098 (9)	−0.0023 (8)	−0.0011 (8)
C4	0.0294 (11)	0.0283 (11)	0.0312 (11)	0.0104 (9)	0.0029 (9)	−0.0020 (9)
C5	0.0281 (11)	0.0382 (13)	0.0422 (13)	0.0161 (10)	−0.0040 (10)	−0.0004 (10)
C6	0.0346 (12)	0.0332 (12)	0.0306 (11)	0.0161 (10)	−0.0085 (9)	−0.0004 (9)
C7	0.0325 (12)	0.0227 (10)	0.0262 (11)	0.0085 (9)	−0.0013 (9)	0.0000 (8)
O1	0.0435 (10)	0.0466 (10)	0.0236 (8)	0.0051 (8)	−0.0070 (7)	0.0026 (7)
O2	0.0361 (9)	0.0280 (8)	0.0288 (8)	0.0104 (7)	−0.0038 (7)	0.0040 (6)
O3	0.0548 (11)	0.0441 (10)	0.0384 (9)	0.0305 (9)	0.0087 (8)	−0.0001 (8)
O4	0.0375 (9)	0.0494 (10)	0.0273 (8)	0.0186 (8)	−0.0069 (7)	0.0045 (7)
O5	0.0448 (10)	0.0472 (10)	0.0254 (8)	0.0162 (8)	0.0030 (7)	0.0031 (7)
O6	0.0359 (9)	0.0611 (12)	0.0386 (10)	0.0205 (9)	0.0089 (8)	0.0012 (8)
OW1	0.0766 (14)	0.0271 (9)	0.0276 (9)	0.0142 (9)	−0.0007 (9)	−0.0006 (7)
OW2	0.0381 (10)	0.0397 (10)	0.0654 (13)	0.0169 (8)	−0.0211 (9)	−0.0031 (9)
OW3	0.0548 (11)	0.0380 (9)	0.0268 (8)	0.0296 (9)	0.0027 (7)	0.0024 (7)
OW4	0.0415 (10)	0.0512 (11)	0.0291 (9)	0.0197 (9)	−0.0010 (8)	−0.0047 (8)
S1	0.0335 (3)	0.0274 (3)	0.0200 (3)	0.0116 (2)	−0.0016 (2)	0.00021 (19)
Mn1	0.0304 (3)	0.0278 (3)	0.0239 (3)	0.0131 (2)	−0.00111 (18)	0.00084 (17)

Geometric parameters (Å, º)

C1—C2	1.372 (3)	O4—H4	0.820
C1—C6	1.398 (3)	O6—H6A	0.820
C1—S1	1.762 (2)	OW1—Mn1	2.1556 (18)
C2—C3	1.391 (3)	OW1—H1A	0.881 (17)
C2—H2	0.930	OW1—H1B	0.892 (17)
C3—C4	1.405 (3)	OW2—Mn1	2.1534 (19)
C3—C7	1.472 (3)	OW2—H2A	0.876 (17)
C4—O6	1.343 (3)	OW2—H2B	0.879 (18)
C4—C5	1.394 (3)	OW3—Mn1	2.2110 (17)
C5—C6	1.373 (3)	OW3—H3A	0.871 (17)
C5—H5	0.930	OW3—H3B	0.879 (17)
C6—H6	0.930	OW4—H4A	0.873 (17)
C7—O5	1.218 (3)	OW4—H4B	0.866 (18)
C7—O4	1.311 (3)	Mn1—OW2^i	2.1534 (19)
O1—S1	1.4544 (17)	Mn1—OW1^i	2.1556 (18)
O2—S1	1.4716 (16)	Mn1—OW3^i	2.2110 (17)
O3—S1	1.4511 (19)
C2—C1—C6	120.0 (2)	Mn1—OW2—H2B	127.9 (19)
C2—C1—S1	118.16 (17)	H2A—OW2—H2B	100 (3)
C6—C1—S1	121.69 (17)	Mn1—OW3—H3A	120.0 (19)
C1—C2—C3	120.9 (2)	Mn1—OW3—H3B	115.1 (19)
C1—C2—H2	119.6	H3A—OW3—H3B	107 (3)
C3—C2—H2	119.6	H4A—OW4—H4B	103 (3)
C2—C3—C4	119.2 (2)	O3—S1—O1	114.68 (12)
C2—C3—C7	120.81 (19)	O3—S1—O2	110.54 (11)
C4—C3—C7	120.0 (2)	O1—S1—O2	110.72 (10)
O6—C4—C5	118.5 (2)	O3—S1—C1	107.02 (10)
O6—C4—C3	122.1 (2)	O1—S1—C1	107.21 (11)
C5—C4—C3	119.4 (2)	O2—S1—C1	106.19 (10)
C6—C5—C4	120.6 (2)	OW2^i—Mn1—OW2	180.0
C6—C5—H5	119.7	OW2^i—Mn1—OW1	89.48 (8)
C4—C5—H5	119.7	OW2—Mn1—OW1	90.52 (8)
C5—C6—C1	119.9 (2)	OW2^i—Mn1—OW1^i	90.52 (8)
C5—C6—H6	120.1	OW2—Mn1—OW1^i	89.48 (8)
C1—C6—H6	120.1	OW1—Mn1—OW1^i	180.0
O5—C7—O4	123.1 (2)	OW2^i—Mn1—OW3	91.05 (8)
O5—C7—C3	123.6 (2)	OW2—Mn1—OW3	88.95 (8)
O4—C7—C3	113.24 (19)	OW1—Mn1—OW3	93.83 (7)
C7—O4—H4	109.5	OW1^i—Mn1—OW3	86.17 (7)
C4—O6—H6A	109.5	OW2^i—Mn1—OW3^i	88.95 (8)
Mn1—OW1—H1A	133.7 (18)	OW2—Mn1—OW3^i	91.05 (8)
Mn1—OW1—H1B	121.0 (18)	OW1—Mn1—OW3^i	86.17 (7)
H1A—OW1—H1B	101 (2)	OW1^i—Mn1—OW3^i	93.83 (7)
Mn1—OW2—H2A	130.2 (19)	OW3—Mn1—OW3^i	180.0
C6—C1—C2—C3	1.1 (3)	S1—C1—C6—C5	175.92 (17)
S1—C1—C2—C3	−174.83 (15)	C2—C3—C7—O5	−175.8 (2)
C1—C2—C3—C4	−1.5 (3)	C4—C3—C7—O5	2.1 (3)
C1—C2—C3—C7	176.38 (19)	C2—C3—C7—O4	3.5 (3)
C2—C3—C4—O6	179.34 (19)	C4—C3—C7—O4	−178.64 (19)
C7—C3—C4—O6	1.4 (3)	C2—C1—S1—O3	−42.3 (2)
C2—C3—C4—C5	0.7 (3)	C6—C1—S1—O3	141.84 (19)
C7—C3—C4—C5	−177.2 (2)	C2—C1—S1—O1	−165.77 (17)
O6—C4—C5—C6	−178.2 (2)	C6—C1—S1—O1	18.3 (2)
C3—C4—C5—C6	0.5 (3)	C2—C1—S1—O2	75.83 (18)
C4—C5—C6—C1	−0.9 (4)	C6—C1—S1—O2	−100.1 (2)
C2—C1—C6—C5	0.1 (3)

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
OW1—H1A···OW4^ii	0.88 (2)	1.94 (2)	2.781 (3)	160 (3)
OW1—H1B···O1^ii	0.89 (2)	1.91 (2)	2.796 (3)	174 (3)
OW2—H2B···O1^iii	0.88 (2)	1.96 (2)	2.836 (3)	177 (3)
OW2—H2A···OW4	0.88 (2)	1.90 (2)	2.777 (3)	176 (3)
OW3—H3B···O2^iv	0.88 (2)	1.90 (2)	2.763 (2)	168 (3)
OW3—H3A···O3	0.87 (2)	1.86 (2)	2.722 (3)	169 (3)
OW4—H4A···O5^v	0.87 (2)	2.03 (2)	2.855 (2)	158 (3)
OW4—H4B···OW3^iii	0.87 (2)	2.13 (2)	2.980 (3)	166 (3)
O4—H4···O2^vi	0.82	1.91	2.693 (2)	159
O6—H6A···O5	0.82	1.90	2.619 (3)	146

Symmetry codes: (ii) −x+1, −y, −z+1; (iii) −x+2, −y+1, −z+1; (iv) x, y+1, z; (v) x, y, z+1; (vi) −x+1, −y, −z.