Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110052856/bi3006sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270110052856/bi3006Isup2.hkl |
For related literature, see: Armstrong et al. (1998); Doeff et al. (1996); Floros et al. (2001); Hosono et al. (2008); Jeong & Manthiram (2001); Mumme (1968); Parant et al. (1971); Sauvage, Baudrin & Tarascon (2007); Sauvage, Laffont, Tarascon & Baudrin (2007).
NaCl (AR grade) was supplied by Beijing Chemical Reagent Company, China. Mn2O3 (99%) was purchased from Aldrich. In a typical synthesis, Mn2O3 and NaCl were mixed together in a molar ratio of 1:20. The mixture was ground in an agate mortar, then transferred to an alumina crucible and kept at 1123 K for 12 h in a muffle furnace. After the reaction was completed, the product was allowed to cool naturally to room temperature in the muffle furnace, then collected, mixed with an appropriate amount of distilled water and sonicated for 10 min. The crude product was finally rinsed with distilled water five times to remove NaCl, before being dried in an oven at 333 K overnight to give the final product. Elemental analysis was performed by energy-dispersive spectroscopy (EDS) using an Oxford INCA energy-dispersive analyser. The result shows a ratio of Na:Mn = 0.5.
Mn and O atoms could be unambiguously located. Atoms Na1, Na2 and Na3 were subsequently located from a difference Fourier map and their site-occupancy factors were refined. At the end of this refinement, R1 reached 0.0586 and all atom sites of the analogous Na4Mn4Ti5O18 structure (Mumme, 1968) were accounted for. At this stage, a peak of about 4 e Å-3 remained in the residual electron density within the S-shaped tunnel, which was included as atom Na4. Subsequent refinement including the site-occupancy factor of Na4 provided the final structure, with R1 = 0.0441.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker 2009); data reduction: SAINT (Bruker 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL97 (Sheldrick, 2008) and Materials Studio (Accelrys 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and publCIF (Westrip, 2010).
Na4.32Mn9O18 | F(000) = 833 |
Mr = 881.78 | Dx = 4.341 Mg m−3 |
Orthorhombic, Pbam | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2 2ab | Cell parameters from 108 reflections |
a = 9.084 (4) Å | θ = 3–25° |
b = 26.311 (10) Å | µ = 8.38 mm−1 |
c = 2.8223 (11) Å | T = 296 K |
V = 674.6 (5) Å3 | Needle, black |
Z = 2 | 0.3 × 0.01 × 0.01 mm |
Bruker SMART APEXII CCD diffractometer | 1099 independent reflections |
Radiation source: fine-focus sealed tube | 912 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
ϕ and ω scans | θmax = 29.8°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −12→11 |
Tmin = 0.656, Tmax = 0.746 | k = −36→28 |
4301 measured reflections | l = −3→3 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.032 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.068 | w = 1/[σ2(Fo2) + (0.0221P)2 + 2.1043P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
1099 reflections | Δρmax = 0.94 e Å−3 |
111 parameters | Δρmin = −0.72 e Å−3 |
Na4.32Mn9O18 | V = 674.6 (5) Å3 |
Mr = 881.78 | Z = 2 |
Orthorhombic, Pbam | Mo Kα radiation |
a = 9.084 (4) Å | µ = 8.38 mm−1 |
b = 26.311 (10) Å | T = 296 K |
c = 2.8223 (11) Å | 0.3 × 0.01 × 0.01 mm |
Bruker SMART APEXII CCD diffractometer | 1099 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 912 reflections with I > 2σ(I) |
Tmin = 0.656, Tmax = 0.746 | Rint = 0.035 |
4301 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | 111 parameters |
wR(F2) = 0.068 | 0 restraints |
S = 1.09 | Δρmax = 0.94 e Å−3 |
1099 reflections | Δρmin = −0.72 e Å−3 |
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 | Occ. (<1) | |
Na1 | 0.2187 (3) | 0.20229 (9) | 0.0000 | 0.0262 (9) | 0.922 (9) |
Na2 | 0.7053 (5) | 0.08465 (18) | 0.5000 | 0.0230 (17) | 0.474 (9) |
Na3 | 0.1233 (5) | 0.00419 (16) | 0.0000 | 0.0298 (17) | 0.532 (9) |
Na4 | 0.7440 (11) | 0.0623 (4) | 0.0000 | 0.027 (4) | 0.233 (9) |
Mn1 | 0.86356 (8) | 0.19353 (3) | 0.5000 | 0.00746 (17) | |
Mn2 | 0.5000 | 0.0000 | 0.0000 | 0.0102 (2) | |
Mn3 | 0.54351 (8) | 0.19491 (3) | 0.0000 | 0.00920 (18) | |
Mn4 | 0.36271 (8) | 0.08892 (3) | 0.5000 | 0.00872 (17) | |
Mn5 | 0.01709 (8) | 0.10997 (3) | 0.0000 | 0.00859 (17) | |
O1 | 0.9700 (4) | 0.06632 (12) | 0.5000 | 0.0122 (7) | |
O2 | 0.9184 (4) | 0.23592 (12) | 0.0000 | 0.0078 (7) | |
O3 | 0.0484 (4) | 0.15959 (12) | 0.5000 | 0.0097 (7) | |
O4 | 0.4998 (4) | 0.07295 (13) | 0.0000 | 0.0104 (7) | |
O5 | 0.2264 (4) | 0.09600 (13) | 0.0000 | 0.0134 (8) | |
O6 | 0.3600 (4) | 0.00300 (13) | 0.5000 | 0.0119 (7) | |
O7 | 0.4321 (4) | 0.16637 (13) | 0.5000 | 0.0129 (8) | |
O8 | 0.6685 (4) | 0.21980 (14) | 0.5000 | 0.0122 (7) | |
O9 | 0.8152 (4) | 0.14674 (13) | 0.0000 | 0.0165 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Na1 | 0.0185 (15) | 0.0181 (15) | 0.0420 (19) | −0.0033 (10) | 0.000 | 0.000 |
Na2 | 0.017 (3) | 0.017 (3) | 0.035 (3) | −0.0042 (19) | 0.000 | 0.000 |
Na3 | 0.030 (3) | 0.013 (2) | 0.047 (3) | 0.0011 (18) | 0.000 | 0.000 |
Na4 | 0.027 (6) | 0.017 (6) | 0.037 (7) | −0.001 (4) | 0.000 | 0.000 |
Mn1 | 0.0092 (4) | 0.0085 (3) | 0.0047 (4) | −0.0003 (3) | 0.000 | 0.000 |
Mn2 | 0.0155 (6) | 0.0115 (5) | 0.0038 (5) | 0.0060 (4) | 0.000 | 0.000 |
Mn3 | 0.0113 (4) | 0.0118 (4) | 0.0044 (4) | −0.0007 (3) | 0.000 | 0.000 |
Mn4 | 0.0112 (4) | 0.0107 (4) | 0.0043 (4) | 0.0011 (3) | 0.000 | 0.000 |
Mn5 | 0.0099 (4) | 0.0113 (4) | 0.0046 (4) | 0.0017 (3) | 0.000 | 0.000 |
O1 | 0.0153 (18) | 0.0106 (17) | 0.0107 (18) | 0.0007 (14) | 0.000 | 0.000 |
O2 | 0.0108 (17) | 0.0081 (16) | 0.0046 (16) | −0.0003 (13) | 0.000 | 0.000 |
O3 | 0.0122 (17) | 0.0100 (16) | 0.0068 (17) | 0.0030 (14) | 0.000 | 0.000 |
O4 | 0.0142 (18) | 0.0122 (17) | 0.0048 (17) | 0.0011 (14) | 0.000 | 0.000 |
O5 | 0.0137 (18) | 0.0191 (19) | 0.0075 (18) | 0.0031 (15) | 0.000 | 0.000 |
O6 | 0.0088 (17) | 0.0208 (19) | 0.0060 (17) | 0.0024 (14) | 0.000 | 0.000 |
O7 | 0.0190 (19) | 0.0148 (18) | 0.0048 (17) | −0.0040 (15) | 0.000 | 0.000 |
O8 | 0.0071 (16) | 0.0217 (18) | 0.0078 (17) | 0.0007 (14) | 0.000 | 0.000 |
O9 | 0.029 (2) | 0.0169 (18) | 0.0040 (17) | −0.0099 (16) | 0.000 | 0.000 |
Mn1—O2 | 1.866 (2) | Na2—Na4i | 1.569 (5) |
Mn1—O8 | 1.902 (4) | Na2—O4 | 2.360 (5) |
Mn1—O9 | 1.924 (2) | Na2—O4i | 2.360 (5) |
Mn1—O2i | 1.866 (2) | Na2—O9i | 2.378 (5) |
Mn1—O3ii | 1.902 (3) | Na2—O9 | 2.378 (5) |
Mn1—O9i | 1.924 (2) | Na2—O6vi | 2.381 (6) |
Mn1—Mn1i | 2.8223 (11) | Na2—O1 | 2.452 (6) |
Mn1—Mn1iii | 2.8223 (11) | Na2—Na2i | 2.8223 (11) |
Mn1—Mn5ii | 2.9615 (11) | Na2—Na2iii | 2.8223 (11) |
Mn1—Mn5iv | 2.9615 (11) | Na2—Na3v | 3.143 (6) |
Mn1—Mn3 | 3.2319 (14) | Na3—Na4v | 2.125 (11) |
Mn2—O4 | 1.919 (3) | Na3—Na3xi | 2.251 (9) |
Mn2—O6 | 1.901 (2) | Na3—O1v | 2.480 (4) |
Mn2—O4v | 1.919 (3) | Na3—O1vi | 2.480 (4) |
Mn2—O6iii | 1.901 (2) | Na3—O1ix | 2.570 (5) |
Mn2—O6vi | 1.901 (2) | Na3—O1viii | 2.570 (5) |
Mn2—O6v | 1.901 (2) | Na3—O6 | 2.572 (5) |
Mn2—Mn2i | 2.8223 (11) | Na3—O6iii | 2.572 (5) |
Mn2—Mn2iii | 2.8223 (11) | Na3—O5 | 2.591 (6) |
Mn2—Mn4 | 3.0035 (10) | Na3—Na3iii | 2.8223 (11) |
Mn2—Mn4v | 3.0035 (10) | Na3—Na3i | 2.8223 (11) |
Mn3—O7 | 1.892 (2) | Na4—Na2iii | 1.569 (5) |
Mn3—O8 | 1.926 (2) | Na4—Na3v | 2.125 (11) |
Mn3—O2vii | 2.146 (3) | Na4—O4 | 2.236 (11) |
Mn3—O7iii | 1.892 (2) | Na4—O9 | 2.314 (10) |
Mn3—O8iii | 1.926 (2) | Na4—O6v | 2.415 (8) |
Mn3—Mn3i | 2.8223 (11) | Na4—O6vi | 2.415 (8) |
Mn3—Mn3iii | 2.8223 (11) | Na4—O1 | 2.493 (9) |
Mn3—Mn1iii | 3.2319 (14) | Na4—O1iii | 2.493 (9) |
Mn4—O4 | 1.928 (2) | Na4—Na4iii | 2.8223 (11) |
Mn4—O5 | 1.886 (2) | O1—Mn5iv | 1.869 (2) |
Mn4—O6 | 2.261 (4) | O1—Mn5ii | 1.869 (2) |
Mn4—O7 | 2.133 (3) | O1—Na3v | 2.480 (4) |
Mn4—O5i | 1.886 (2) | O1—Na3vi | 2.480 (4) |
Mn4—O4i | 1.928 (2) | O1—Na4i | 2.493 (9) |
Mn4—Mn4i | 2.8223 (11) | O1—Na3ii | 2.570 (5) |
Mn4—Mn4iii | 2.8223 (11) | O1—Na3iv | 2.570 (5) |
Mn4—Mn2i | 3.0035 (10) | O2—Mn1iii | 1.866 (2) |
Mn5—O3 | 1.943 (2) | O2—Mn3xii | 2.146 (3) |
Mn5—O5 | 1.937 (4) | O2—Na1xii | 2.436 (4) |
Mn5—O1viii | 1.869 (2) | O2—Na1ii | 2.868 (4) |
Mn5—O1ix | 1.869 (2) | O3—Mn1ix | 1.902 (3) |
Mn5—O3iii | 1.943 (2) | O3—Mn5i | 1.943 (2) |
Mn5—O9ix | 2.074 (4) | O3—Na1i | 2.376 (3) |
Mn5—Mn5i | 2.8223 (11) | O4—Mn4iii | 1.928 (2) |
Mn5—Mn5iii | 2.8223 (11) | O4—Na2iii | 2.360 (5) |
Mn5—Mn1ix | 2.9615 (12) | O5—Mn4iii | 1.886 (2) |
Mn5—Mn1viii | 2.9615 (11) | O6—Mn2i | 1.901 (2) |
Na1—O3iii | 2.376 (3) | O6—Na2vi | 2.381 (6) |
Na1—O3 | 2.376 (3) | O6—Na4v | 2.415 (8) |
Na1—O2vii | 2.436 (4) | O6—Na4vi | 2.415 (8) |
Na1—O8vii | 2.530 (4) | O6—Na3i | 2.572 (5) |
Na1—O8x | 2.530 (4) | O7—Mn3i | 1.892 (2) |
Na1—O7 | 2.577 (4) | O7—Na1i | 2.577 (4) |
Na1—O7iii | 2.577 (4) | O8—Mn3i | 1.926 (2) |
Na1—O5 | 2.798 (4) | O8—Na1xiii | 2.530 (4) |
Na1—O2ix | 2.868 (4) | O8—Na1xii | 2.530 (4) |
Na1—Na1i | 2.8223 (11) | O9—Mn1iii | 1.924 (2) |
Na1—Na1iii | 2.8223 (11) | O9—Mn5ii | 2.074 (4) |
Na2—Na4 | 1.569 (5) | O9—Na2iii | 2.378 (5) |
Na1i—Na1—Na1iii | 180.00 (19) | Mn3i—Mn3—Mn3iii | 180.0 |
Na4—Na2—Na2i | 154.1 (3) | Mn3i—Mn3—Mn1 | 64.111 (15) |
Na4i—Na2—Na2i | 25.9 (3) | Mn3iii—Mn3—Mn1 | 115.889 (15) |
Na4—Na2—Na2iii | 25.9 (3) | O7iii—Mn3—Mn1iii | 98.70 (10) |
Na4i—Na2—Na2iii | 154.1 (3) | O7—Mn3—Mn1iii | 143.37 (11) |
Na4—Na2—Na3v | 37.5 (3) | O8—Mn3—Mn1iii | 78.08 (9) |
Na4i—Na2—Na3v | 90.8 (4) | O8iii—Mn3—Mn1iii | 32.17 (10) |
Na2i—Na2—Na3v | 116.68 (5) | O2vii—Mn3—Mn1iii | 119.09 (8) |
Na2iii—Na2—Na3v | 63.32 (5) | Mn3i—Mn3—Mn1iii | 115.889 (15) |
Mn4—Na2—Na3v | 121.46 (15) | Mn3iii—Mn3—Mn1iii | 64.111 (15) |
Na4v—Na3—Na3xi | 118.9 (4) | Mn1—Mn3—Mn1iii | 51.78 (3) |
Na4v—Na3—Na3iii | 90.0 | O5—Mn4—O5i | 96.85 (17) |
Na3xi—Na3—Na3iii | 90.0 | O5—Mn4—O4i | 173.07 (15) |
Na4v—Na3—Na3i | 90.0 | O5i—Mn4—O4i | 84.14 (12) |
Na3xi—Na3—Na3i | 90.0 | O5—Mn4—O4 | 84.14 (12) |
Na2iii—Na4—Na2 | 128.2 (7) | O5i—Mn4—O4 | 173.07 (15) |
Na2iii—Na4—Na3v | 115.8 (4) | O4i—Mn4—O4 | 94.06 (15) |
Na2—Na4—Na3v | 115.8 (4) | O5—Mn4—O7 | 95.72 (12) |
Na2iii—Na4—Na4iii | 25.9 (3) | O5i—Mn4—O7 | 95.72 (12) |
Na2—Na4—Na4iii | 154.1 (4) | O4i—Mn4—O7 | 91.00 (12) |
Na3v—Na4—Na4iii | 90.0 | O4—Mn4—O7 | 91.00 (12) |
O2i—Mn1—O2 | 98.25 (15) | O5—Mn4—O6 | 95.24 (12) |
O2i—Mn1—O3ii | 92.59 (13) | O5i—Mn4—O6 | 95.24 (12) |
O2—Mn1—O3ii | 92.59 (13) | O4i—Mn4—O6 | 77.83 (12) |
O2i—Mn1—O8 | 91.80 (13) | O4—Mn4—O6 | 77.83 (12) |
O2—Mn1—O8 | 91.80 (13) | O7—Mn4—O6 | 163.45 (13) |
O3ii—Mn1—O8 | 173.29 (15) | Mn4i—Mn4—Mn4iii | 180.00 (6) |
O2i—Mn1—O9 | 176.48 (15) | Mn4i—Mn4—Mn2 | 118.024 (14) |
O2—Mn1—O9 | 83.61 (11) | Mn4iii—Mn4—Mn2 | 61.976 (14) |
O3ii—Mn1—O9 | 84.32 (14) | Mn4i—Mn4—Mn2i | 61.976 (14) |
O8—Mn1—O9 | 91.13 (15) | Mn4iii—Mn4—Mn2i | 118.024 (14) |
O2i—Mn1—O9i | 83.61 (11) | Mn2—Mn4—Mn2i | 56.05 (3) |
O2—Mn1—O9i | 176.48 (15) | O1viii—Mn5—O1ix | 98.05 (16) |
O3ii—Mn1—O9i | 84.32 (14) | O1viii—Mn5—O5 | 96.21 (13) |
O8—Mn1—O9i | 91.13 (15) | O1ix—Mn5—O5 | 96.21 (13) |
O9—Mn1—O9i | 94.38 (16) | O1viii—Mn5—O3 | 173.99 (14) |
Mn1i—Mn1—Mn1iii | 180.00 (8) | O1ix—Mn5—O3 | 84.15 (11) |
Mn1i—Mn1—Mn5ii | 118.457 (15) | O5—Mn5—O3 | 89.08 (12) |
Mn1iii—Mn1—Mn5ii | 61.543 (15) | O1viii—Mn5—O3iii | 84.15 (11) |
Mn1i—Mn1—Mn5iv | 61.543 (15) | O1ix—Mn5—O3iii | 173.99 (14) |
Mn1iii—Mn1—Mn5iv | 118.457 (15) | O5—Mn5—O3iii | 89.08 (12) |
Mn5ii—Mn1—Mn5iv | 56.91 (3) | O3—Mn5—O3iii | 93.13 (15) |
Mn1i—Mn1—Mn3 | 115.889 (15) | O1viii—Mn5—O9ix | 94.82 (13) |
Mn1iii—Mn1—Mn3 | 64.111 (15) | O1ix—Mn5—O9ix | 94.82 (13) |
Mn5ii—Mn1—Mn3 | 102.94 (3) | O5—Mn5—O9ix | 163.13 (15) |
Mn5iv—Mn1—Mn3 | 129.79 (3) | O3—Mn5—O9ix | 79.39 (12) |
O6vi—Mn2—O6iii | 180.0 (3) | O3iii—Mn5—O9ix | 79.39 (12) |
O6vi—Mn2—O6v | 95.83 (15) | Mn5i—Mn5—Mn1ix | 61.543 (15) |
O6iii—Mn2—O6v | 84.17 (15) | Mn5iii—Mn5—Mn1ix | 118.457 (15) |
O6vi—Mn2—O6 | 84.17 (15) | Mn5i—Mn5—Mn1viii | 118.457 (15) |
O6iii—Mn2—O6 | 95.83 (15) | Mn5iii—Mn5—Mn1viii | 61.543 (15) |
O6v—Mn2—O6 | 180.0 (3) | Mn1ix—Mn5—Mn1viii | 56.91 (3) |
O6vi—Mn2—O4v | 87.59 (13) | Mn5iv—O1—Mn5ii | 98.05 (16) |
O6iii—Mn2—O4v | 92.41 (13) | Mn1iii—O2—Mn1 | 98.25 (15) |
O6v—Mn2—O4v | 87.59 (13) | Mn1iii—O2—Mn3xii | 130.40 (8) |
O6—Mn2—O4v | 92.41 (13) | Mn1—O2—Mn3xii | 130.40 (8) |
O6vi—Mn2—O4 | 92.41 (13) | Mn1ix—O3—Mn5 | 100.74 (13) |
O6iii—Mn2—O4 | 87.59 (13) | Mn1ix—O3—Mn5i | 100.74 (13) |
O6v—Mn2—O4 | 92.41 (13) | Mn5—O3—Mn5i | 93.13 (15) |
O6—Mn2—O4 | 87.59 (13) | Mn2—O4—Mn4iii | 102.62 (13) |
O4v—Mn2—O4 | 180.0 (2) | Mn2—O4—Mn4 | 102.62 (13) |
Mn2i—Mn2—Mn2iii | 180.0 | Mn4iii—O4—Mn4 | 94.06 (15) |
Mn2i—Mn2—Mn4 | 61.976 (14) | Mn4—O5—Mn4iii | 96.85 (17) |
Mn2iii—Mn2—Mn4 | 118.024 (14) | Mn4—O5—Mn5 | 131.53 (8) |
Mn2i—Mn2—Mn4v | 118.024 (14) | Mn4iii—O5—Mn5 | 131.53 (8) |
Mn2iii—Mn2—Mn4v | 61.976 (14) | Mn2i—O6—Mn2 | 95.83 (15) |
Mn4—Mn2—Mn4v | 180.00 (3) | Mn2i—O6—Mn4 | 91.96 (12) |
O7iii—Mn3—O7 | 96.45 (16) | Mn2—O6—Mn4 | 91.96 (12) |
O7iii—Mn3—O8 | 175.42 (16) | Mn3i—O7—Mn3 | 96.45 (16) |
O7—Mn3—O8 | 84.49 (11) | Mn3i—O7—Mn4 | 122.50 (11) |
O7iii—Mn3—O8iii | 84.49 (11) | Mn3—O7—Mn4 | 122.50 (11) |
O7—Mn3—O8iii | 175.42 (16) | Mn1—O8—Mn3 | 115.20 (14) |
O8—Mn3—O8iii | 94.23 (16) | Mn1—O8—Mn3i | 115.20 (14) |
O7iii—Mn3—O2vii | 93.05 (12) | Mn3—O8—Mn3i | 94.23 (16) |
O7—Mn3—O2vii | 93.05 (12) | Mn1—O9—Mn1iii | 94.38 (16) |
O8—Mn3—O2vii | 91.37 (13) | Mn1—O9—Mn5ii | 95.54 (14) |
O8iii—Mn3—O2vii | 91.37 (13) | Mn1iii—O9—Mn5ii | 95.54 (14) |
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z; (iii) x, y, z−1; (iv) x+1, y, z+1; (v) −x+1, −y, −z; (vi) −x+1, −y, −z+1; (vii) x−1/2, −y+1/2, z; (viii) x−1, y, z−1; (ix) x−1, y, z; (x) x−1/2, −y+1/2, z−1; (xi) −x, −y, −z; (xii) x+1/2, −y+1/2, z; (xiii) x+1/2, −y+1/2, z+1. |
Experimental details
Crystal data | |
Chemical formula | Na4.32Mn9O18 |
Mr | 881.78 |
Crystal system, space group | Orthorhombic, Pbam |
Temperature (K) | 296 |
a, b, c (Å) | 9.084 (4), 26.311 (10), 2.8223 (11) |
V (Å3) | 674.6 (5) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 8.38 |
Crystal size (mm) | 0.3 × 0.01 × 0.01 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.656, 0.746 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4301, 1099, 912 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.699 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.068, 1.09 |
No. of reflections | 1099 |
No. of parameters | 111 |
Δρmax, Δρmin (e Å−3) | 0.94, −0.72 |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and Materials Studio (Accelrys 2005), SHELXL97 (Sheldrick, 2008) and publCIF (Westrip, 2010).
Mn1—O2 | 1.866 (2) | Mn3—O8 | 1.926 (2) |
Mn1—O8 | 1.902 (4) | Mn3—O2vi | 2.146 (3) |
Mn1—O9 | 1.924 (2) | Mn4—O4 | 1.928 (2) |
Mn1—O2i | 1.866 (2) | Mn4—O5 | 1.886 (2) |
Mn1—O3ii | 1.902 (3) | Mn4—O6 | 2.261 (4) |
Mn2—O4 | 1.919 (3) | Mn4—O7 | 2.133 (3) |
Mn2—O6 | 1.901 (2) | Mn5—O3 | 1.943 (2) |
Mn2—O4iii | 1.919 (3) | Mn5—O5 | 1.937 (4) |
Mn2—O6iv | 1.901 (2) | Mn5—O1vii | 1.869 (2) |
Mn2—O6v | 1.901 (2) | Mn5—O1viii | 1.869 (2) |
Mn3—O7 | 1.892 (2) |
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z; (iii) −x+1, −y, −z; (iv) x, y, z−1; (v) −x+1, −y, −z+1; (vi) x−1/2, −y+1/2, z; (vii) x−1, y, z−1; (viii) x−1, y, z. |
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Na4Mn9O18 has been investigated as an electrode material (Hosono et al., 2008; Sauvage, Laffont et al., 2007) and sodium-ion sensor (Sauvage, Baudrin et al., 2007) because of its unique double-tunnel structure that can facilitate Na+ mobility. The crystal structure of Na4Mn9O18 was believed to be essentially similar to that of Na4Mn4Ti5O18 (Mumme, 1968; Parant et al., 1971), and this has been testified by Rietveld refinement against powder X-ray (Floros et al., 2001; Doeff et al., 1996) and neutron (Armstrong et al., 1998) diffraction data. To date, however, the small crystal size of Na4Mn9O18 samples has prevented accurate structure refinement from single-crystal data. In previous reports, there were some indications that the sodium stoichiometry in Na4Mn9O18 was higher than 4 (Jeong & Manthiram, 2001), suggesting a more complicated distribution of Na+ ions in the tunnels compared with that established to date.
We report here the structure of the title compound, Na4.32Mn9O18, which was prepared by reacting Mn2O3 with NaCl. Na4.32Mn9O18 crystallizes in an orthorhombic structure (space group Pbam) that contains 18 crystallographically independent atoms: five Mn, nine O and four Na. The refined framework structure is consistent with the structure model of Na4Mn4Ti5O18 (Mumme, 1968). Specifically, the Na4.32Mn9O18 crystal structure is composed of single chains of edge-linked MnO5 square pyramids (Mn3) and double (Mn1 and Mn5) and triple (Mn2 and two Mn4) chains of edge-linked MnO6 octahedra. Each central MnO6 octahedron of the triple chains (Mn2) shares six edges with six other neighbouring distorted octahedra. These single, double and triple chains share the vertices of the polyhedra and form two types of tunnel parallel to the c axis, namely large S-shaped tunnels and small six-sided tunnels (Figs. 1 and 2). The large tunnel comprises ten MnO6 octahedra and two MnO5 square pyramids, while the small one is composed of four MnO6 octahedra and two MnO5 square pyramids.
A tendency for Mn3+/Mn4+ charge ordering within Na1.1Ca1.8Mn9O18 has been proposed, based on both the insulating nature of the compound and the Mn—O bond lengths refined from powder X-ray diffraction data (Floros et al., 2001). In Na4.32Mn9O18, Mn3+ is likely to occupy preferentially the Mn3 and Mn4 sites, since these have relatively elongated environments (Table 1). Hence, charge ordering of Mn3+/Mn4+ is also suggested by the structure of Na4.32Mn9O18.
Four crystallographically distinct Na+ sites exist within the tunnels of Na4.32Mn9O18. Na1 resides in the six-sided tunnel, while the others (Na2, Na3, Na4) reside in the large S-shaped tunnel (Fig. 1). The Na+ sites are all positioned on mirror planes perpendicular to the c axis. Na1 is coordinated by nine O atoms (Fig. 3). The O3, O7 and O8 sites on each side of the mirror plane form a triangular prism, while three additional O atoms on the mirror plane are located out from the three prism faces. The coordination polyhedra of atoms Na2, Na3 and Na4 are essentially similar to that of Na1 (Fig. 3). In each case, the Na atom is again at the centre of a triangular prism, while Na3 has an additional O atom out from a face. Atoms Na1, Na3 and Na4 are located at z = 0, while atom Na2 is located at z = 1/2. Na4 resides between Na2 and Na3, where the nearest Na4—Na2 and Na4—Na3 distances are 1.569 (5) and 2.125 (11) Å, respectively. This excludes simultaneous occupation of the Na4 site and neighbouring Na2 or Na3 sites, and suggests that the occupancy of the Na4 site is low. The Na1 site located in the six-sided tunnel has a refined occupancy of 0.922 (9), while the Na sites (Na2, Na3 and Na4) in the S-shaped tunnel have refined occupancies of 0.474 (9), 0.532 (9) and 0.233 (9), respectively. The sample composition refines overall to be Na4.32Mn9O18, in good agreement with energy-dispersive spectroscopy results, which show an Na:Mn ratio of 1:2.
The Na stoichiometry in Na4Mn9O18 has previously been recognized to be higher than 4 (Jeong & Manthiram, 2001), although the reason for this has remained unclear. The Na4 site discovered here accounts for the excess Na+ within the structure. The Na4 site may be attributable to the repulsion balance of Na+ within the tunnel. Because the Na2, Na3 and Na4 sites are not fully occupied, coupled with the fact that there is no evidence from the single-crystal or powder X-ray diffraction data to indicate long-range ordering of Na+, the Na+ ions are likely situated with a short-range order within each tunnel (Armstrong et al., 1998). The scheme of the ordering will rely on the distances between the Na2, Na3 and Na4 sites in the S-shaped tunnel. In general, the Na+ ions should be distributed evenly on the sites within the S-shaped tunnel to achieve repulsion balance. It is noteworthy that Na3 and Na4 have the same z value, but they are not likely to appear in the same cell with the same z value.
Fig. 4 shows a possible local ordered distribution of Na+ in the S-shaped tunnel. Because of the existence of the additional Na4 site, the ordering scheme is more complicated than that proposed by Armstrong et al. (1998). The nearest distance between Na2 and Na4 [1.569 (5) Å] is avoided. The repulsions between Na2 and Na3, Na4 and Na3, and Na2 and Na4 are all balanced. Finally, the resulting occupancies of Na2, Na3 and Na4 are 1/2, 1/2 and 1/4, respectively, corresponding to an ideal composition of Na4.5Mn9O18 (equivalent to Na0.5MnO2).
It has been reported that the unit cell of Na4Mn9O18 varies with Na content upon charging/discharging, in which only the Na2 and Na3 sites in the S-shaped tunnel are movable (Sauvage, Baudrin et al., 2007). Sodium deinsertion from Na4Mn9O18 results in a decrease for b (with a and c remaining essentially unchanged), while sodium insertion causes slight variation of b with a large variation of a and c. The existence of the Na4 site between Na2 and Na3 results in fewer vacant sites and stronger repulsion along b than along a and c, which may make the lattice strain along b achieve its upper limit at the composition Na4.5Mn9O18. As a result, sodium deinsertion from Na4.5Mn9O18, no matter from which site in the S-shaped tunnel, relieves the lattice strain along b and leads to a larger contraction along b than along a and c. In contrast, sodium insertion into Na4.5Mn9O18 will mainly diffuse into the Na2 and Na3 sites, because the nearest distance between Na2 and Na4 is too small for Na4 to be accessed. Therefore, the vacancy along a and c is preferentially filled, which leads to expansion mainly along a and c.