Δ-Aqua-S-citrato(2–)­manganese(II)

The citrato(2−) ligand in aqua­citrato(2−)­manganese(II), [Mn(C₆H₆O₇)(H₂O)], chelates the Mn atom through the α-hydroxyl, the α-carboxyl and one β-carboxyl O atom, while the other β-carboxyl­ic acid group remains uncoordinated. Each O atom of the α-carboxyl groups is bonded to an adjacent Mn atom, leading to octahedral Mn and a helical chain. Neighboring chains are consolidated into a tightly held crystal structure by hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.048
• wR factor = 0.094
• Data-to-parameter ratio = 12.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_710  Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle #      2
                   O2  -MN1 -O1  -C1    -60.00  4.00   4.556   1.555   1.555   1.555

PLAT_710  Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle #     19
                   O1W -MN1 -O4  -C4     69.70  0.90   1.555   1.555   1.555   1.555

PLAT_731  Alert C Bond    Calc     0.84(3), Rep   0.850(10) ....       3.00 su-Ratio
                     O6   -H6O     1.555   1.555

PLAT_731  Alert C Bond    Calc     0.85(4), Rep   0.850(10) ....       4.00 su-Ratio
                     O1W  -H1W2    1.555   1.555

PLAT_731  Alert C Bond    Calc     0.85(3), Rep   0.850(10) ....       3.00 su-Ratio
                     C3   -H3B     1.555   1.555

PLAT_731  Alert C Bond    Calc     0.85(3), Rep   0.850(10) ....       3.00 su-Ratio
                     C5   -H5B     1.555   1.555

PLAT_733  Alert C Torsion Calc   -7.48(16), Rep    -7.48(7) ....       2.29 su-Ratio
                     O2  -MN1 -O2  -MN1    4.556   1.555   1.555   4.456

PLAT_745  Alert C D-H     Calc     0.84(3), Rep     0.85000 ....    Missing su
                     O1   -H1O     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(3), Rep     0.85000 ....    Missing su
                     O6   -H6O     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.85(4), Rep     0.85000 ....    Missing su
                     O1W  -H1W2    1.555   1.555

PLAT_745  Alert C D-H     Calc   0.849(13), Rep     0.85000 ....    Missing su
                     O1W  -H1W1    1.555   1.555

PLAT_746  Alert C H...A   Calc     1.75(3), Rep     1.75000 ....    Missing su
                     H1O  -O5      1.555   3.655

PLAT_746  Alert C H...A   Calc     1.81(3), Rep     1.81000 ....    Missing su
                     H6O  -O5      1.555   2.565

PLAT_746  Alert C H...A   Calc     2.09(4), Rep     2.10000 ....    Missing su
                     H1W2 -O4      1.555   4.556

PLAT_746  Alert C H...A   Calc   1.893(12), Rep     1.90000 ....    Missing su
                     H1W1 -O7      1.555   4.566

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           28.20
         From the CIF: _reflns_number_total               1936
         Count of symmetry unique reflns         1232
         Completeness (_total/calc)            157.14%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured       704
         Fraction of Friedel pairs measured     0.571
         Are heavy atom types Z>Si present          yes
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 15 Alert Level C = Please check

---

S1. Comment

The chemistry of the metal derivatives of citric acid is of interest owing to the importance of this acid in physiological processes (Glusker, 1980; Mayer et al., 2002). An early structural study on a 3:2 Mn derivative of citric acid had documented a compound having the formulation [Mn(OH₂)₆][Mn(C₆H₅O₇)·(OH₂)]₂·2H₂O (Carrell & Glusker, 1973; Glusker & Carrell, 1973). A more recent study reported [NH₄]₄[Mn(C₆H₅O₇)₂] (Matzapetakis et al., 2000), which is separated from neutral solution in a 1:2 molar ratio of Mn^{2+ _{and citric acid. In our hands, an acidic synthesis yielded the 1:1 ratio citratomanganese monohydrate with free β-carboxylic acid group (Fig. 1 and Table 1). The citrato dianion chelates tridentately to the water-coordinated Mn atom through two carboxyl and α-hydroxyl O atoms. The bonded O atom of α-carboxyl groups is further coordinated to an adjacent Mn atom [Mn—O}}i ^{2.290 (3) Å; symmetry code: (i) 1/2 + x, 1/2 − y, 1 − z], and the other O atom of this carboxyl group is also bonded strongly to another Mn atom [Mn—O}ii ^{2.142 (3) Å; symmetry code: (ii) 1 + x, y, z]. The Mn atom thereby exists in an octahedral coordination geometry. Adjacent molecules are linked by a screw-axial translation to form a helical chain running along the a axis of the crystal (Fig. 2). Neighboring chains are consolidated into a tightly held chain structure by hydrogen bonds (Table 2).}

S2. Experimental

Manganese dichloride (0.99 g, 5 mol) and citric acid monohydrate (2.10 g, 10 mmol) were dissolved in water (10 ml). The pH of the solution was adjusted to 1.5–3.0 by the addition of ammonium hydroxide. The mixture was warmed and then filtered. The solution was left in the refrigerator for several days. Colorless crystals of the compound were obtained in 90% yield. Elemental analysis. Found (calculated) for C₆H₈O₈Mn (%): C 27.1 (27.4), H 2.8 (3.1). IR (KBr): 3481, 3397, 2974, 2292, 2618, 2531, 1732, 1594, 1546, 1475, 1417, 1395, 1323, 1284, 1260, 1153, 1072, 890. 581, 540 cm⁻¹.

S3. Refinement

The H atoms of the hydroxyl group and the water molecule were located and refined, subject to O—H = 0.85±0.01 and H···H = 1.39±0.01 Å. The C-bound H atoms were generated geometrically (C—H = 0.97 Å), and their displacement parameters were set to 1.2 times those of their parent atoms. [Please clarify: all the H-atom coordinates in the atom list have s.u. values, is this correct?]

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. ORTEPII (Johnson, 1976) plot of aquacitrato(2-)manganese, with ellipsoids drawn at the 50% probability level. H atoms are drawn as spheres of arbitrary radii. [Symmetry codes: (i) x, y, 1 + z; (ii) 3/2 + x, 1/2 − y, −z.]
	Fig. 2. ORTEPII (Johnson, 1976) plot depicting the helical chain propagating along the a axis.

Δ-Aqua-S-citrato(2-)manganese(II)

Crystal data

[Mn(C6H6O7)(H2O)]	Dx = 2.040 Mg m^−3
Mr = 263.06	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 2130 reflections
a = 6.030 (1) Å	θ = 2.5–28.2°
b = 10.467 (1) Å	µ = 1.57 mm^−1
c = 13.568 (1) Å	T = 298 K
V = 856.4 (2) Å^3	Plate, colorless
Z = 4	0.29 × 0.09 × 0.08 mm
F(000) = 532

Data collection

Bruker APEX area-detector diffractometer	1936 independent reflections
Radiation source: fine-focus sealed tube	1914 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ϕ and ω scans	θmax = 28.2°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→7
Tmin = 0.662, Tmax = 0.889	k = −7→13
5277 measured reflections	l = −17→17

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)] = 0.048	Only H-atom coordinates refined
wR(F^2) = 0.094	w = 1/[σ^2(Fo^2) + (0.0243P)^2 + 1.1167P] where P = (Fo^2 + 2Fc^2)/3
S = 1.21	(Δ/σ)max = 0.011
1936 reflections	Δρmax = 0.50 e Å^−3
160 parameters	Δρmin = −0.46 e Å^−3
11 restraints	Absolute structure: ad (Flack & Schwarzenbach, 1988)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.05 (3)

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

	x	y	z	Uiso*/Ueq
Mn1	0.5946 (1)	0.33199 (5)	0.44853 (4)	0.0132 (2)
O1	0.4604 (5)	0.4990 (3)	0.3799 (2)	0.0156 (6)
O2	0.2213 (5)	0.3352 (3)	0.4800 (2)	0.0176 (6)
O3	−0.0829 (6)	0.3704 (3)	0.3897 (2)	0.0236 (7)
O4	0.4665 (5)	0.2358 (3)	0.3166 (2)	0.0182 (7)
O5	0.3837 (6)	0.2248 (2)	0.1576 (2)	0.0210 (7)
O6	0.1039 (8)	0.6292 (3)	0.4979 (2)	0.0329 (8)
O7	0.1345 (6)	0.8052 (3)	0.4082 (3)	0.0310 (9)
O1w	0.6686 (6)	0.4344 (3)	0.5833 (2)	0.0297 (8)
C1	0.2454 (7)	0.4781 (3)	0.3398 (3)	0.0122 (8)
C2	0.1170 (8)	0.3889 (3)	0.4098 (3)	0.0134 (8)
C3	0.2694 (8)	0.4114 (4)	0.2395 (3)	0.0168 (9)
C4	0.3823 (7)	0.2829 (3)	0.2382 (3)	0.0147 (8)
C5	0.1214 (8)	0.6039 (4)	0.3255 (3)	0.0147 (8)
C6	0.1219 (8)	0.6909 (3)	0.4142 (3)	0.0183 (9)
H1o	0.511 (7)	0.572 (2)	0.366 (3)	0.019*
H6o	0.118 (9)	0.678 (4)	0.547 (2)	0.039*
H1w1	0.668 (7)	0.515 (1)	0.590 (4)	0.036*
H1w2	0.789 (5)	0.403 (4)	0.605 (4)	0.036*
H3a	0.142 (3)	0.397 (4)	0.215 (3)	0.020*
H3b	0.346 (5)	0.457 (4)	0.200 (2)	0.020*
H5a	−0.017 (2)	0.595 (4)	0.316 (3)	0.018*
H5b	0.179 (5)	0.646 (4)	0.278 (2)	0.018*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mn1	0.0111 (3)	0.0133 (2)	0.0153 (3)	0.0006 (3)	−0.0022 (3)	0.0035 (2)
O1	0.008 (2)	0.013 (1)	0.026 (2)	−0.002 (1)	−0.0046 (1)	0.007 (1)
O2	0.019 (2)	0.021 (1)	0.013 (1)	0.001 (1)	0.001 (1)	0.006 (1)
O3	0.013 (2)	0.030 (2)	0.028 (2)	−0.005 (1)	−0.001 (2)	0.005 (1)
O4	0.023 (2)	0.015 (1)	0.017 (1)	0.004 (1)	−0.005 (1)	0.001 (1)
O5	0.029 (2)	0.018 (1)	0.017 (1)	0.010 (1)	−0.002 (2)	−0.004 (1)
O6	0.061 (2)	0.021 (1)	0.017 (2)	0.003 (2)	0.004 (2)	−0.005 (1)
O7	0.042 (3)	0.014 (1)	0.037 (2)	0.000 (1)	−0.007 (2)	−0.003 (1)
O1w	0.040 (2)	0.018 (1)	0.031 (2)	0.006 (1)	−0.010 (2)	−0.004 (1)
C1	0.009 (2)	0.011 (2)	0.017 (2)	−0.001 (2)	−0.000 (2)	0.000 (1)
C2	0.017 (2)	0.009 (1)	0.014 (2)	0.002 (2)	0.005 (2)	−0.001 (1)
C3	0.017 (2)	0.017 (2)	0.017 (2)	0.002 (2)	−0.000 (2)	0.001 (2)
C4	0.012 (2)	0.016 (2)	0.016 (2)	−0.004 (2)	0.007 (2)	−0.002 (2)
C5	0.013 (2)	0.016 (2)	0.015 (2)	0.002 (2)	0.001 (2)	−0.001 (1)
C6	0.012 (2)	0.018 (2)	0.025 (2)	0.002 (2)	−0.001 (2)	−0.004 (2)

Geometric parameters (Å, º)

Mn1—O1	2.139 (3)	C1—C2	1.540 (5)
Mn1—O2	2.292 (3)	C1—C3	1.536 (5)
Mn1—O2^i	2.142 (3)	C1—C5	1.526 (5)
Mn1—O3^ii	2.140 (4)	C3—C4	1.508 (6)
Mn1—O4	2.195 (3)	C5—C6	1.509 (5)
Mn1—O1w	2.166 (3)	O1—H1o	0.85 (1)
O1—C1	1.423 (5)	O6—H6o	0.85 (1)
O2—C2	1.272 (5)	O1w—H1w1	0.85 (1)
O3—C2	1.251 (6)	O1w—H1w2	0.85 (1)
O4—C4	1.278 (5)	C3—H3a	0.85 (1)
O5—C4	1.251 (4)	C3—H3b	0.85 (1)
O6—C6	1.311 (5)	C5—H5a	0.85 (1)
O7—C6	1.201 (5)	C5—H5b	0.85 (1)
O1—Mn1—O2	72.4 (1)	C2—O3—Mn1^iv	145.5 (3)
O1—Mn1—O2^i	178.4 (1)	C4—O4—Mn1	129.9 (2)
O1—Mn1—O3^ii	91.6 (1)	O1—C1—C5	111.3 (3)
O1—Mn1—O4	83.5 (1)	O1—C1—C3	108.8 (3)
O1—Mn1—O1w	92.4 (1)	C5—C1—C3	109.0 (3)
O2^i—Mn1—O2	106.15 (9)	O1—C1—C2	108.3 (3)
O2^i—Mn1—O1w	87.1 (1)	C5—C1—C2	110.8 (3)
O2^i—Mn1—O4	96.9 (1)	C3—C1—C2	108.5 (3)
O3^ii—Mn1—O2	163.6 (1)	O3—C2—O2	124.8 (4)
O3^ii—Mn1—O2^i	89.9 (1)	O3—C2—C1	116.4 (3)
O3^ii—Mn1—O4	95.9 (1)	O2—C2—C1	118.8 (4)
O3^ii—Mn1—O1w	92.0 (1)	C4—C3—C1	117.3 (3)
O4—Mn1—O2	79.2 (1)	O5—C4—O4	122.5 (4)
O1w—Mn1—O2	92.2 (1)	O5—C4—C3	116.6 (4)
O1w—Mn1—O4	171.2 (1)	O4—C4—C3	120.9 (3)
C1—O1—Mn1	112.7 (2)	C6—C5—C1	114.7 (3)
C2—O2—Mn1^iii	121.6 (3)	O7—C6—O6	123.6 (4)
C2—O2—Mn1	110.7 (3)	O7—C6—C5	123.2 (4)
Mn1^iii—O2—Mn1	115.0 (1)	O6—C6—C5	113.2 (3)
O3^ii—Mn1—O1—C1	139.7 (2)	Mn1^iv—O3—C2—C1	−148.8 (3)
O2^i—Mn1—O1—C1	−60 (4)	Mn1^iii—O2—C2—O3	16.5 (5)
O1w—Mn1—O1—C1	−128.3 (3)	Mn1—O2—C2—O3	156.1 (3)
O4—Mn1—O1—C1	44.0 (2)	Mn1^iii—O2—C2—C1	−160.0 (2)
O2—Mn1—O1—C1	−36.7 (2)	Mn1—O2—C2—C1	−20.4 (4)
O1—Mn1—O2—C2	30.7 (2)	O1—C1—C2—O3	173.7 (3)
O3^ii—Mn1—O2—C2	17.9 (5)	C5—C1—C2—O3	51.4 (4)
O2^i—Mn1—O2—C2	−150.0 (3)	C3—C1—C2—O3	−68.3 (4)
O1w—Mn1—O2—C2	122.5 (2)	O1—C1—C2—O2	−9.6 (4)
O4—Mn1—O2—C2	−55.9 (2)	C5—C1—C2—O2	−131.9 (4)
O1—Mn1—O2—Mn1^iii	173.17 (16)	C3—C1—C2—O2	108.4 (4)
O3^ii—Mn1—O2—Mn1^iii	160.4 (3)	O1—C1—C3—C4	60.2 (5)
O2^i—Mn1—O2—Mn1^iii	−7.48 (7)	C5—C1—C3—C4	−178.3 (4)
O1w—Mn1—O2—Mn1^iii	−95.05 (14)	C2—C1—C3—C4	−57.5 (5)
O4—Mn1—O2—Mn1^iii	86.63 (13)	Mn1—O4—C4—O5	155.5 (3)
O1—Mn1—O4—C4	7.5 (4)	Mn1—O4—C4—C3	−26.2 (6)
O3^ii—Mn1—O4—C4	−83.5 (4)	C1—C3—C4—O5	174.1 (4)
O2^i—Mn1—O4—C4	−174.1 (4)	C1—C3—C4—O4	−4.3 (6)
O1w—Mn1—O4—C4	69.7 (9)	O1—C1—C5—C6	−49.4 (5)
O2—Mn1—O4—C4	80.7 (4)	C3—C1—C5—C6	−169.4 (4)
Mn1—O1—C1—C5	159.5 (3)	C2—C1—C5—C6	71.2 (4)
Mn1—O1—C1—C3	−80.3 (3)	C1—C5—C6—O7	143.1 (5)
Mn1—O1—C1—C2	37.5 (3)	C1—C5—C6—O6	−37.9 (6)
Mn1^iv—O3—C2—O2	34.7 (7)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1o···O5^v	0.85	1.75	2.594 (4)	178
O6—H6o···O5^vi	0.85	1.81	2.652 (4)	173
O1w—H1w2···O4^i	0.85	2.10	2.871 (4)	152
O1w—H1w1···O7^vii	0.85	1.90	2.737 (4)	172

Symmetry codes: (i) x+1/2, −y+1/2, −z+1; (v) −x+1, y+1/2, −z+1/2; (vi) −x+1/2, −y+1, z+1/2; (vii) x+1/2, −y+3/2, −z+1.