Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109004442/dn3102sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270109004442/dn3102Isup2.hkl | |
Portable Document Format (PDF) file https://doi.org/10.1107/S0108270109004442/dn3102fig3sup3.pdf | |
Portable Document Format (PDF) file https://doi.org/10.1107/S0108270109004442/dn3102fig4sup4.pdf |
CCDC reference: 730080
All chemicals were of analytical grade and were used without further purification. The synthesis of the title compound was carried out by hydrothermal reaction. Equimolar amounts (3.45 mmol) of MnIVO2, squaric acid and maleic acid (H4C4O4) and 3 ml of water were placed in a Teflon-lined autoclave (Paar) at 453 K for 60 h. It has been demonstrated that the addition of maleic acid is necessary to form the title compound even if its role has not been explained. The mixture was then cooled to ambient temperature at 1 K min−1 leading to the formation of brown prismatic crystals. They were washed with water and dried under air.
The remaining maximum residual density located in the voids of the crystal structure (0, −0.007, 3/4) could be attributed to a solvent water molecule, but refinement of this position leads to large atomic displacement parameters. All H atoms were found from difference Fourier syntheses or XHYDEX (Orpen, 1980). They were refined with soft restraints applied on distances to their parent O atoms [0.960 (8) Å] and on H···H distances [1.520 (8) Å] according to the geometry of the water molecule. The isotropic displacement parameters of the H atoms were fixed equal to 1.5Ueq of their parent O atom.
Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and DIAMOND (Brandenburg & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).
[Mn3(C4O4)3(H2O)6]·H2O | F(000) = 1252 |
Mr = 627.04 | Dx = 1.83 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 13776 reflections |
a = 11.5921 (2) Å | θ = 2.6–35.0° |
b = 11.8471 (2) Å | µ = 1.73 mm−1 |
c = 16.5666 (7) Å | T = 293 K |
β = 90.084 (1)° | Prism, brown |
V = 2275.13 (11) Å3 | 0.19 × 0.17 × 0.17 mm |
Z = 4 |
Nonius KappaCCD diffractometer | 4984 independent reflections |
Radiation source: fine-focus sealed tube | 3452 reflections with I > 2σ(I) |
Horizonally mounted graphite crystal monochromator | Rint = 0.030 |
Nonius CCD scans | θmax = 35.0°, θmin = 3.5° |
Absorption correction: multi-scan (Blessing, 1995) | h = −18→15 |
Tmin = 0.739, Tmax = 0.759 | k = −18→19 |
19216 measured reflections | l = −26→26 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.038 | Only H-atom coordinates refined |
wR(F2) = 0.102 | w = 1/[σ2(Fo2) + (0.0472P)2 + 2.1926P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max = 0.001 |
4984 reflections | Δρmax = 1.31 e Å−3 |
172 parameters | Δρmin = −0.42 e Å−3 |
9 restraints | Extinction correction: (SHELXL97; Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0013 (2) |
[Mn3(C4O4)3(H2O)6]·H2O | V = 2275.13 (11) Å3 |
Mr = 627.04 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 11.5921 (2) Å | µ = 1.73 mm−1 |
b = 11.8471 (2) Å | T = 293 K |
c = 16.5666 (7) Å | 0.19 × 0.17 × 0.17 mm |
β = 90.084 (1)° |
Nonius KappaCCD diffractometer | 4984 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 3452 reflections with I > 2σ(I) |
Tmin = 0.739, Tmax = 0.759 | Rint = 0.030 |
19216 measured reflections |
R[F2 > 2σ(F2)] = 0.038 | 9 restraints |
wR(F2) = 0.102 | Only H-atom coordinates refined |
S = 1.05 | Δρmax = 1.31 e Å−3 |
4984 reflections | Δρmin = −0.42 e Å−3 |
172 parameters |
Experimental. Temperature-dependent X-ray diffraction was performed under flowing air with a powder diffractometer equipped with a curved-position-sensitive detector (INEL CPS 120) and a high-temperature attachment from Rigaku. The detector was used in a semi-focusing arrangement by reflection (Cu Kα1 radiation). With this geometry, the stationary sample is deposited on a flat sample holder located at the centre of the goniometer. An angle of 6 ° was selected between the incident beam and the surface of the sample. To ensure satisfactory counting statistics, a counting time of 2700?s/pattern was selected for the thermal decomposition. Decomposition was carried out with a heating rate of 5?K?h-1 between 293 and 673?K and 25?K?h-1 until 873?K. Thermogravimetric measurements were performed with a Rigaku Thermoflex instrument in dynamic air. The measurement was carried out with a heating rate of 5?K?h-1 between 293 and 673?K and 25?K?h-1 until 1273?K. The magnetic susceptibility measurements were performed on a randomly oriented single-crystal (78.4?mg) from 2 to 300?K with an applied field of 1 kOe using a MPMS-XL SQUID magnetometer from Quantum Design. |
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. |
x | y | z | Uiso*/Ueq | ||
Mn1 | −0.2500 | 0.2500 | 0.0000 | 0.01296 (8) | |
Mn2 | 0.2500 | 0.2500 | 0.0000 | 0.01302 (8) | |
Mn3 | 0.0000 | 0.50860 (3) | 0.2500 | 0.01294 (8) | |
O1 | 0.20676 (12) | 0.31326 (11) | 0.37934 (7) | 0.0274 (3) | |
O2 | 0.11181 (12) | 0.63805 (11) | 0.19979 (7) | 0.0261 (3) | |
O3 | 0.30623 (12) | 0.21316 (12) | 0.12187 (7) | 0.0271 (3) | |
O4 | 0.11822 (12) | 0.38320 (12) | 0.20032 (8) | 0.0276 (3) | |
O5 | −0.07924 (10) | 0.17652 (10) | −0.00473 (9) | 0.0273 (3) | |
O6 | 0.18034 (10) | 0.07779 (10) | −0.00556 (9) | 0.0275 (3) | |
OW1 | −0.33056 (12) | 0.09739 (10) | 0.04113 (8) | 0.0249 (3) | |
H1A | −0.2927 (19) | 0.0258 (11) | 0.0401 (13) | 0.037* | |
H1B | −0.3647 (18) | 0.1034 (17) | 0.0932 (7) | 0.037* | |
OW2 | 0.40821 (11) | 0.17252 (11) | −0.03788 (8) | 0.0254 (3) | |
H2A | 0.4154 (18) | 0.1490 (19) | −0.0922 (6) | 0.038* | |
H2B | 0.4787 (12) | 0.2071 (19) | −0.0227 (12) | 0.038* | |
OW3 | 0.07866 (12) | 0.50798 (10) | 0.36726 (8) | 0.0241 (3) | |
H3A | 0.1205 (15) | 0.5746 (9) | 0.3823 (14) | 0.036* | |
H3B | 0.1301 (14) | 0.4473 (10) | 0.3801 (14) | 0.036* | |
C1 | 0.23383 (15) | 0.28490 (15) | 0.30885 (10) | 0.0194 (3) | |
C2 | 0.31609 (15) | 0.20657 (14) | 0.27244 (10) | 0.0189 (3) | |
C3 | 0.27780 (15) | 0.24096 (14) | 0.19189 (10) | 0.0189 (3) | |
C4 | 0.19410 (15) | 0.31814 (14) | 0.22825 (10) | 0.0196 (3) | |
C5 | −0.03701 (15) | 0.07942 (14) | −0.00221 (11) | 0.0201 (3) | |
C6 | 0.08123 (14) | 0.03576 (14) | −0.00246 (12) | 0.0202 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Mn1 | 0.01239 (15) | 0.01306 (15) | 0.01343 (16) | 0.00017 (12) | −0.00070 (12) | −0.00034 (11) |
Mn2 | 0.01422 (16) | 0.01230 (15) | 0.01254 (16) | 0.00012 (12) | −0.00016 (12) | 0.00031 (11) |
Mn3 | 0.01276 (14) | 0.01282 (15) | 0.01325 (15) | 0.000 | 0.00060 (11) | 0.000 |
O1 | 0.0378 (7) | 0.0331 (7) | 0.0113 (6) | 0.0202 (6) | 0.0011 (5) | −0.0002 (5) |
O2 | 0.0321 (7) | 0.0308 (7) | 0.0153 (6) | −0.0202 (6) | −0.0003 (5) | −0.0011 (5) |
O3 | 0.0361 (7) | 0.0342 (7) | 0.0111 (6) | 0.0193 (6) | 0.0001 (5) | −0.0004 (5) |
O4 | 0.0332 (7) | 0.0327 (7) | 0.0170 (6) | 0.0232 (6) | −0.0039 (5) | −0.0023 (5) |
O5 | 0.0139 (5) | 0.0125 (5) | 0.0554 (9) | 0.0033 (4) | 0.0005 (6) | −0.0001 (5) |
O6 | 0.0125 (5) | 0.0138 (5) | 0.0562 (9) | −0.0022 (4) | 0.0022 (6) | −0.0019 (5) |
OW1 | 0.0333 (7) | 0.0167 (5) | 0.0247 (7) | −0.0020 (5) | 0.0083 (6) | 0.0022 (5) |
OW2 | 0.0165 (6) | 0.0305 (7) | 0.0292 (7) | 0.0001 (5) | 0.0036 (5) | −0.0095 (5) |
OW3 | 0.0294 (7) | 0.0202 (6) | 0.0226 (6) | 0.0004 (5) | −0.0108 (5) | −0.0006 (5) |
C1 | 0.0242 (8) | 0.0220 (7) | 0.0120 (7) | 0.0101 (7) | −0.0007 (6) | −0.0001 (6) |
C2 | 0.0230 (8) | 0.0212 (8) | 0.0126 (7) | 0.0097 (6) | 0.0011 (6) | 0.0000 (6) |
C3 | 0.0231 (8) | 0.0211 (8) | 0.0125 (7) | 0.0094 (6) | −0.0005 (6) | 0.0003 (5) |
C4 | 0.0241 (8) | 0.0221 (8) | 0.0126 (7) | 0.0104 (6) | −0.0007 (6) | −0.0013 (6) |
C5 | 0.0126 (6) | 0.0132 (7) | 0.0345 (10) | −0.0011 (6) | −0.0002 (6) | −0.0010 (6) |
C6 | 0.0141 (7) | 0.0132 (6) | 0.0332 (9) | 0.0006 (6) | 0.0010 (7) | −0.0004 (6) |
Mn1—OW1 | 2.1465 (12) | O6—C6 | 1.253 (2) |
Mn1—O5 | 2.1640 (12) | OW1—H1A | 0.955 (7) |
Mn1—O1i | 2.1922 (12) | OW1—H1B | 0.953 (8) |
Mn2—OW2 | 2.1456 (12) | OW2—H2A | 0.946 (8) |
Mn2—O3 | 2.1652 (12) | OW2—H2B | 0.947 (7) |
Mn2—O6 | 2.1960 (12) | OW3—H3A | 0.959 (8) |
Mn3—OW3 | 2.1448 (13) | OW3—H3B | 0.957 (8) |
Mn3—O2 | 2.1742 (12) | C1—C2 | 1.462 (2) |
Mn3—O4 | 2.1831 (12) | C1—C4 | 1.466 (2) |
O1—C1 | 1.255 (2) | C2—C3 | 1.464 (2) |
O2—C2ii | 1.252 (2) | C3—C4 | 1.464 (2) |
O3—C3 | 1.250 (2) | C5—C6iii | 1.460 (2) |
O4—C4 | 1.257 (2) | C5—C6 | 1.465 (2) |
O5—C5 | 1.2508 (19) | ||
OW1—Mn1—OW1iv | 180.00 (7) | O2i—Mn3—O4i | 87.76 (6) |
OW1—Mn1—O5iv | 85.92 (5) | OW3—Mn3—O4 | 94.18 (5) |
OW1iv—Mn1—O5iv | 94.08 (5) | OW3i—Mn3—O4 | 85.55 (5) |
OW1—Mn1—O5 | 94.08 (5) | O2—Mn3—O4 | 87.76 (6) |
OW1iv—Mn1—O5 | 85.92 (5) | O2i—Mn3—O4 | 177.67 (5) |
O5iv—Mn1—O5 | 180.0 | O4i—Mn3—O4 | 94.23 (8) |
OW1—Mn1—O1i | 95.60 (5) | C1—O1—Mn1i | 134.39 (11) |
OW1iv—Mn1—O1i | 84.40 (5) | C2ii—O2—Mn3 | 135.62 (11) |
O5iv—Mn1—O1i | 92.14 (6) | C3—O3—Mn2 | 137.10 (11) |
O5—Mn1—O1i | 87.86 (6) | C4—O4—Mn3 | 135.86 (11) |
OW1—Mn1—O1v | 84.40 (5) | C5—O5—Mn1 | 136.61 (11) |
OW1iv—Mn1—O1v | 95.60 (5) | C6—O6—Mn2 | 134.78 (11) |
O5iv—Mn1—O1v | 87.86 (6) | Mn1—OW1—H1A | 122.8 (14) |
O5—Mn1—O1v | 92.14 (6) | Mn1—OW1—H1B | 114.0 (13) |
O1i—Mn1—O1v | 180.0 | H1A—OW1—H1B | 105.8 (10) |
OW2—Mn2—OW2vi | 180.00 (8) | Mn2—OW2—H2A | 118.7 (13) |
OW2—Mn2—O3 | 86.00 (5) | Mn2—OW2—H2B | 118.3 (13) |
OW2vi—Mn2—O3 | 94.00 (5) | H2A—OW2—H2B | 107.6 (11) |
OW2—Mn2—O3vi | 94.00 (5) | Mn3—OW3—H3A | 116.5 (13) |
OW2vi—Mn2—O3vi | 86.00 (5) | Mn3—OW3—H3B | 117.9 (13) |
O3—Mn2—O3vi | 180.0 | H3A—OW3—H3B | 104.2 (10) |
OW2—Mn2—O6 | 84.53 (5) | O1—C1—C2 | 135.89 (15) |
OW2vi—Mn2—O6 | 95.47 (5) | O1—C1—C4 | 134.17 (15) |
O3—Mn2—O6 | 87.82 (6) | C2—C1—C4 | 89.94 (13) |
O3vi—Mn2—O6 | 92.18 (6) | O2vii—C2—C1 | 134.07 (15) |
OW2—Mn2—O6vi | 95.47 (5) | O2vii—C2—C3 | 135.79 (15) |
OW2vi—Mn2—O6vi | 84.53 (5) | C1—C2—C3 | 90.14 (12) |
O3—Mn2—O6vi | 92.18 (6) | O3—C3—C2 | 133.82 (15) |
O3vi—Mn2—O6vi | 87.82 (6) | O3—C3—C4 | 136.23 (15) |
O6—Mn2—O6vi | 180.00 (2) | C2—C3—C4 | 89.94 (13) |
OW3—Mn3—OW3i | 179.61 (7) | O4—C4—C3 | 134.05 (15) |
OW3—Mn3—O2 | 95.51 (5) | O4—C4—C1 | 135.96 (15) |
OW3i—Mn3—O2 | 84.77 (5) | C3—C4—C1 | 89.97 (12) |
OW3—Mn3—O2i | 84.77 (5) | O5—C5—C6iii | 136.39 (16) |
OW3i—Mn3—O2i | 95.51 (5) | O5—C5—C6 | 133.69 (16) |
O2—Mn3—O2i | 90.28 (8) | C6iii—C5—C6 | 89.92 (13) |
OW3—Mn3—O4i | 85.55 (5) | O6—C6—C5iii | 134.07 (15) |
OW3i—Mn3—O4i | 94.18 (5) | O6—C6—C5 | 135.85 (16) |
O2—Mn3—O4i | 177.67 (5) | C5iii—C6—C5 | 90.08 (13) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x, −y, −z; (iv) −x−1/2, −y+1/2, −z; (v) x−1/2, −y+1/2, z−1/2; (vi) −x+1/2, −y+1/2, −z; (vii) −x+1/2, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
OW1—H1A···O6iii | 0.96 (1) | 1.88 (1) | 2.7730 (18) | 155 (2) |
OW1—H1B···O2viii | 0.95 (1) | 1.83 (1) | 2.7554 (19) | 162 (2) |
OW2—H2A···O4vi | 0.95 (1) | 1.87 (1) | 2.7873 (18) | 162 (2) |
OW2—H2B···O5vi | 0.95 (1) | 1.86 (1) | 2.7609 (18) | 158 (2) |
OW3—H3A···O3ii | 0.96 (1) | 1.85 (1) | 2.7787 (19) | 162 (2) |
OW3—H3B···O1 | 0.96 (1) | 1.82 (1) | 2.7505 (18) | 163 (2) |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x, −y, −z; (vi) −x+1/2, −y+1/2, −z; (viii) x−1/2, y−1/2, z. |
Experimental details
Crystal data | |
Chemical formula | [Mn3(C4O4)3(H2O)6]·H2O |
Mr | 627.04 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 11.5921 (2), 11.8471 (2), 16.5666 (7) |
β (°) | 90.084 (1) |
V (Å3) | 2275.13 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.73 |
Crystal size (mm) | 0.19 × 0.17 × 0.17 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (Blessing, 1995) |
Tmin, Tmax | 0.739, 0.759 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19216, 4984, 3452 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.808 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.102, 1.05 |
No. of reflections | 4984 |
No. of parameters | 172 |
No. of restraints | 9 |
H-atom treatment | Only H-atom coordinates refined |
Δρmax, Δρmin (e Å−3) | 1.31, −0.42 |
Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and DIAMOND (Brandenburg & Berndt, 2001), WinGX (Farrugia, 1999).
Mn1—OW1 | 2.1465 (12) | O3—C3 | 1.250 (2) |
Mn1—O5 | 2.1640 (12) | O4—C4 | 1.257 (2) |
Mn1—O1i | 2.1922 (12) | O5—C5 | 1.2508 (19) |
Mn2—OW2 | 2.1456 (12) | O6—C6 | 1.253 (2) |
Mn2—O3 | 2.1652 (12) | C1—C2 | 1.462 (2) |
Mn2—O6 | 2.1960 (12) | C1—C4 | 1.466 (2) |
Mn3—OW3 | 2.1448 (13) | C2—C3 | 1.464 (2) |
Mn3—O2 | 2.1742 (12) | C3—C4 | 1.464 (2) |
Mn3—O4 | 2.1831 (12) | C5—C6iii | 1.460 (2) |
O1—C1 | 1.255 (2) | C5—C6 | 1.465 (2) |
O2—C2ii | 1.252 (2) | ||
O1—C1—C2 | 135.89 (15) | O4—C4—C3 | 134.05 (15) |
O1—C1—C4 | 134.17 (15) | C3—C4—C1 | 89.97 (12) |
C2—C1—C4 | 89.94 (13) | O5—C5—C6iii | 136.39 (16) |
O2iv—C2—C1 | 134.07 (15) | O5—C5—C6 | 133.69 (16) |
O2iv—C2—C3 | 135.79 (15) | C6iii—C5—C6 | 89.92 (13) |
C1—C2—C3 | 90.14 (12) | O6—C6—C5iii | 134.07 (15) |
O3—C3—C2 | 133.82 (15) | O6—C6—C5 | 135.85 (16) |
O3—C3—C4 | 136.23 (15) | C5iii—C6—C5 | 90.08 (13) |
C2—C3—C4 | 89.94 (13) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x, −y, −z; (iv) −x+1/2, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
OW1—H1A···O6iii | 0.955 (7) | 1.880 (11) | 2.7730 (18) | 154.7 (19) |
OW1—H1B···O2v | 0.953 (8) | 1.833 (10) | 2.7554 (19) | 162 (2) |
OW2—H2A···O4vi | 0.946 (8) | 1.872 (9) | 2.7873 (18) | 162 (2) |
OW2—H2B···O5vi | 0.947 (7) | 1.861 (11) | 2.7609 (18) | 158 (2) |
OW3—H3A···O3ii | 0.959 (8) | 1.850 (10) | 2.7787 (19) | 162 (2) |
OW3—H3B···O1 | 0.957 (8) | 1.820 (9) | 2.7505 (18) | 163.2 (18) |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x, −y, −z; (v) x−1/2, y−1/2, z; (vi) −x+1/2, −y+1/2, −z. |
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The design and construction of metal–organic frameworks (MOFs), based on the concepts of building units, scale chemistry and interconnected networks [see, for example, Férey (2000) and O'Keeffe et al. (2000)], have attracted increasing interest in recent years owing to the versatility of the new topologies that can be prepared. MOFs possess numerous applications, including selective sorption and separation, ion exchange, catalysis, gas detection and molecule storage (Férey et al., 2005; Roswell & Yaghi, 2005, and references therein; Pan et al., 2006). Multidentate organic ligands have been widely used to conceive new architectures. Efforts have focused mainly on carboxylates, whereas oxocarbon dianions have been less thoroughly investigated. Nevertheless, in association with transition metals, the salt of 3,4-dihydroxy-3-cyclobutene-1,2-dione (C4H2O4), also known as squaric acid, allows the design of new topologies composed of chains (Lee et al., 1996; Alleyne et al., 1998), layers (Lee et al., 1996; Lin & Lii, 1997; Näther et al., 2002) and three-dimensional frameworks (Lee et al., 1996; Lin & Lii, 1997; Neeraj et al., 2002; Greve & Näther, 2002). The last case is more rarely encountered, because stacking of the square anions frequently occurs. Furthermore, the squarate dianion can act as a terminal, chelating or µ to µ6 bridging ligand, offering a wide range of possibile new designs.
In this context, detailed structural information is required in order to understand the properties of MOFs. The present study describes the crystal structure of the title compound, (I), a new three-dimensional open-framework manganese squarate. The compound was initially identified from powder X-ray diffraction, and pattern indexing suggested that it was new. It was subsequently verified that the powder pattern was in agreement with the pattern calculated from the single-crystal structure determination. The crystal structure of (I) (Fig. 1) is built from MnO6 octahedra connected through squarate oxoanions. Each polyhedron is surrounded by 12 octahedra via four oxoanions, and each squarate anion is connected to four metal atoms. This arrangement generates a three-dimensional metal–squarate framework. It can be described by cube-shaped secondary building units (SBUs) connected to one another through common faces (Fig. 2). Each unit comprises Mn1O6 and Mn2O6 octahedra, which are located alternately at the vertices of the unit, the squarate groups SQ1 (C1–C4/O1–O4) and SQ2 [C5/C6/O5/O6/C5vii/C6vii/O5vii/O6vii); symmetry code: (vii) −x, −y, −z], located at the centre of each edge along the c axis and the a and b axes, respectively, and an Mn3O6 octahedron, which is located at the centre of the SBU.
Each unit, with dimensions a × b × 1/2 c, contains two octahedra (four Mn1O6 and four Mn2O6 located on the corners of the cubic SBU and one Mn3O6 at the centre of the SBU) and three squarate groups (four SQ1 and eight SQ2 located on the edges of the cubic SBU). There are no interactions between the neighbouring squarate groups, since the stacking distance between square centroids is too high (Hunter & Sander, 1990; Tsuzuki et al., 2002). Solvent-accessible voids were calculated by means of the programs SQUEEZE/SOLV included in PLATON (Spek, 2009). The total volume available for guest molecules is 448 Å3, which corresponds to approximately 20% of the total unit-cell volume. The total electron count is 45, i.e. 10 electrons per void, which is sufficient to accommodate one water molecule. The largest residual peak (1.31 e Å−3) in the final refinement is located in the void (0, −0.007, 3/4). Attempts to include a water molecule in the model have been made. The largest residual peak droped to 0.84 e Å−3, with comparable reliability factors. Unfortunately, the atomic displacement parameters could not be refined satisfactorily and diverged to large values, and therefore no additional water molecule has been included in the model. If SQUEEZE data are used for the refinement, the largest residual peak drops to 0.48 e.Å−3 and the R factor drops to 0.035.
There are 12 Mn atoms in the unit cell, lying on three crystallographically independent special positions, viz. Mn1 (4d) and Mn2 (4c) on an inversion centre, and Mn3 (4e) on a twofold axis. Each Mn atom is surrounded by two water molecules and four O atoms belonging to four different squarate groups. Each polygon is a near regular octahedron, with the four atoms of the square base strictly in the same plane for Mn1O6 and Mn2O6 and nearly planar for Mn3O6 (the mean-square deviation is 0.0229 Å). The two atoms in apical positions (two water molecules) are equidistant from the mean plane, at the shortest Mn—O distances (Table 1). The mean Mn—O distance [2.17 (2) Å in the three octahedra; Table 1] is in agreement with the value 2.197 Å calculated by the bond-valence method (Brown, 1996) and with the mean distances reported by Alleyne et al. (1998), Näther et al. (2002), Greve & Näther (2002) and Neeraj et al. (2002) for six-coordinated Mn atoms in squarate compounds. There are 12 squarate anions in the unit cell, lying on two sets of crystallographically independent general positions. Both oxoanions have the same µ4 tetra-monodentate connection mode (η1: η1: η1: η1; Fig. 1 and Table 1). The mean distances [C—C = 1.462 (2) Å and C—O = 1.252 (1) Å for SQ1, and C—C = 1.464 (2) Å and C—O = 1.253 (3) Å for SQ2] and angles [C—C—C = 90.0 (1)° for SQ1 and SQ2] within the squarate groups are close to the values reported by West (1980). Moreover, the SQ2 group is strictly planar because it is located accross a centre of inversion, and SQ1 is nearly planar, with a mean atomic deviation from the least-squares plane of 0.0197 Å.
Furthermore, the structure is reinforced by a three-dimensional network of hydrogen bonds [D···A = 2.7505 (18)–2.7873 (18) Å; Table 2] between the coordinated water molecules, as H-atom donors, and O atoms belonging to the squarate anions, as acceptors.
Three other manganese squarates have already been reported, namely Mn(µ2-C4O4)(H2O)4 (Weiss et al., 1986), which crystallizes in the monoclinic system [space group Cc, a = 9.054 (8) Å, b = 13.506 (11) Å, c = 6.711 (6) Å, β = 95.41°] and which is isotypic to the iron squarate analogue (Frankenbach et al., 1992); Mn(µ4-C4O4)(H2O)2 (Neeraj et al., 2002), which crystallizes in the trigonal system [space group R3, a = 11.607 (5) Å, c = 14.66 (3) Å; reduced rhombohedral unit cell: a = 8.294 Å, α = 88.88°]; and Mn(µ4-C4O4)(H2O)2·0.93H2O (Greve & Näther, 2002), which crystallizes in the cubic system [space group Pn3n, a = 16.5527 (8) Å (= reduced cell)]. The tetrahydrate squarate is made up of adjacent chains and dehydration to the dihydrate squarate leads to a condensation of the crystal structure. The two other reported manganese squarates possess three-dimensional frameworks. The title compound is a polymorph of the trigonal dihydrate squarate and is a pseudopolymorph of the partially hydrated cubic squarate. These three squarates display strong crystal structure relationships. Indeed, the crystal structures of the trigonal and cubic manganese squarates can also be described in terms of similar cube-shaped SBUs made of two MnO6 octahedra and three squarate anions, and the reduced unit cell is related to that of the title compound (a = b = c = 16.567 Å, α = β = 90.06° and γ = 91.25°). The three reduced unit cells are approximately orthogonal and their volumes are twice, four times or 16 times that of the SBU (~285 Å3) for the trigonal squarate, the title compound and the cubic squarate, respectively. Thus, the smallest repeating unit is that of the trigonal structure. The multiplicity arises from the relative positions of the squarate groups within one SBU in each poly- or pseudo-polymorph squarate. In the trigonal squarate polymorph, the squarate groups are eclipsed and related by lattice translations in all three directions. In the cubic squarate pseudo-polymorph, the squarate groups are staggered in all three directions, leading to a doubling of all three unit-cell parameters. As an intermediate case, in the title compound, the squarate groups are staggered in the direction of the c axis and eclipsed in the two other directions, leading to the doubling of only one axis.
Alternatively, the three-dimensional coordination frameworks of the three manganese poly- or pseudo-polymorph squarates can be described from cubic cages generated by the assembling of six squarate dianions as already described for the cubic squarate (Greve & Näther, 2002).
Thermogravimetric analyses and temperature-dependent X-ray diffraction showed that the compound dehydrates in one step from room temperature until about 473 K and the anhydrous squarate decomposes to yield cubic Mn2O3 (see supplementary materials). After diamagnetic contribution corrections, the resulting χT versus T variation suggested paramagnetic behaviour [4.14 × 10−2 < χM < 1.75 cm3 mol−1; χ and χM are the magnetic and molar magnetic susceptibilities, respectively]. The curve of 1/χ as a function of temperature T was fitted with a Curie law. The magnetic moment µ obtained from the straight line agrees well with the expected value for an MnII cation (µexp = 5.86 µB, µth = 5.8—5.9 µB; µB is the Bohr magneton). The interatomic distances between metallic centres are too high to allow strong magnetic ineteractions.