PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2008 January 1; 64(Pt 1): m116–m117.
Published online 2007 December 6. doi:  10.1107/S1600536807064525
PMCID: PMC2915069

Monoclinic polymorph of poly[[di-μ-aqua-triaquadi-μ-oxalato-barium(II)­copper(II)] monohydrate]

Abstract

A monoclinic polymorph of the title compound, {[BaCu(C2O4)2(H2O)5]·H2O}n, is reported. The structure is best described as a coordination polymer where the CuII and BaII centers are coordinated by five and nine O atoms, respectively, in capped quadratic antiprismatic and tetragonal pyramidal geometries. The polymerization arises due to the presence of bridging mono- and bidentate oxalate ligands as well as bridging water mol­ecules. The crystal structure is consolidated by a three-dimensional network of hydrogen bonding.

Related literature

For related literature, see: Bélombé et al. (2003 [triangle], 2006 [triangle]); Belombe, Nenwa, Bebga et al. (2007 [triangle]); Bélombé, Nenwa, Mbiangué et al. (2007 [triangle]); Bouayad et al. (1995 [triangle]); Nenwa (2004 [triangle]). For synthesis, see: Kirschner (1960 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-0m116-scheme1.jpg

Experimental

Crystal data

  • [BaCu(C2O4)2(H2O)5]·H2O
  • M r = 485.02
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0m116-efi8.jpg
  • a = 15.744 (2) Å
  • b = 10.7565 (15) Å
  • c = 15.345 (2) Å
  • β = 97.331 (2)°
  • V = 2577.5 (6) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 4.76 mm−1
  • T = 293 (2) K
  • 0.28 × 0.14 × 0.10 mm

Data collection

  • Bruker APEX CCD area detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2001 [triangle]) T min = 0.462, T max = 0.631
  • 17321 measured reflections
  • 3213 independent reflections
  • 3180 reflections with I > 2σ(I)
  • R int = 0.022

Refinement

  • R[F 2 > 2σ(F 2)] = 0.020
  • wR(F 2) = 0.050
  • S = 1.32
  • 3213 reflections
  • 228 parameters
  • 12 restraints
  • All H-atom parameters refined
  • Δρmax = 0.49 e Å−3
  • Δρmin = −1.00 e Å−3

Data collection: SMART (Bruker, 1998 [triangle]); cell refinement: SAINT (Bruker, 2000 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: DIAMOND (Brandenburg, 1999 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807064525/tk2219sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807064525/tk2219Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors are grateful to Klaus Kruse (RWTH Aachen) for technical support during the X-ray experiments.

supplementary crystallographic information

Comment

Bouayad et al. (1995) reported the structure of the title compound, (I), in the triclinic space group P-1. Herein, a new polymorph of (I) is reported which crystallizes in the monoclinic space group C2/c. It was obtained unintentionally from aqueous solution during an on-going study of oxalate-based multifunctional materials (Bélombé et al., 2003, 2006; Belombe, Nenwa, Bebga et al., 2007; Bélombé, Nenwa, Mbiangué et al., 2007; Nenwa, 2004), and is formulated as {[Ba(H2O)4][Cu(C2O4)2(H2O)].H2O}n. The two polymorphs structurally differ with respect to their crystal systems as well as in their coordination modes around the metal centers and in the formation of their lattice networks in the bulk.

The lattice network reported by Bouayad et al. (1995) was shown to be a coordination polymer where each oxalate ion acts as a bidentate ligand, coordinating the metal centers in three different modes: first with the "internal", then with the "external" O atoms linked, respectively to CuII and BaII centers (thus generating pentacyclic rings) and, finally, with one "internal" and one "external" oxalato-O atoms bound to a neighboring Ba atom (thus forming a tetracyclic ring). In that structure, each CuII ion is hexa-coordinated by six O atoms that define a highly distorted octahedral geometry. By contrast, in the monoclinic polymorph, the CuII atom is penta-coordinated in an approximately square pyramidal geometry defined by five O atoms, with the Cu site slightly displaced from the least-squares plane through the O1–O4 atoms towards the axial water-O10 atom (Fig. 1). Therein, the coordination sphere around each BaII center which assumes coordination number nine, as opposed to coordination number eleven in the triclinic polymorph, is emphasized. In the monoclinic form, the Ba site is located approximately at the center of a capped tetragonal antiprism, reminiscent of the geometry around the K+site in the salt K[Cr(C2O4)2(H2O)2] (Bélombé et al., 2006). Selected geometric parameters for the monoclinic polymorph are listed in Table 1 and compare very well with the published data for the triclinic polymorph (Bouayad et al., 1995).

Taken individually, the [Cu(C2O4)2(H2O)]2- complex anions are virtually the same but are connected differently in the triclinic and monoclinic polymorphs. In the monoclinic polymorph, these ions are interconnected into layers parallel to the (101) plane via O–H···O bridges which involve the uncoordinated water molecules (Fig. 2). The 3-D polymerization arises from the linkage of "external" oxalato-O atoms to neighboring Ba centers via mono- or bi-dentate coordination modes, and by single and double water bridges across the O10 and O15/O15i atoms, respectively (Table 2). The latter double bridge interconnects the next two neighboring Ba atoms, related by a center of inversion, with a Ba···Ba separation of 4.788 (2) Å.

In conclusion, the present study reveals that the unit cell symmetry in both structural polymorphs is basically dictated by the differing spatial orientations of the common anionic complexes, [Cu(C2O4)2(H2O)]2-, and variable coordination modes of the BaII centers.

Experimental

Compound (I) was obtained by mixing Ba(NO3)2 (0.31 g, 1.2 mmol, Riedel-de Haën, pure) and K2[Cu(C2O4)2].2H2O (0.18 g, 0.51 mmol), freshly prepared according to the method of Kirschner (1960), in warm water (60 °C; 100 ml). A solid precipitated immediately. The mixture was stirred for about 1 h at the same temperature and left to stand undisturbed over three days at ambient temperature. The blue prismatic crystals that formed were isolated by filtration, dried in air and one of these was used in the X-ray diffraction analysis.

Refinement

All water-bound H atoms were first located in a difference Fourier map and then refined with distance restraints of O–H = 0.83 (3) Å with all Uiso(H) freely refined. The highest peak and deepest hole in the final difference Fourier map are, respectively, 0.49 Å from atom H13B and 1.00 Å from Cu.

Figures

Fig. 1.
A view of the molecular structure of (I), expanded to show the coordination geometry around the BaII center, showing atom-numbering scheme and 50% probability displacement ellipsoids. Symmetry codes: (i) -x, y, -z + 1/2; (ii) x, -y + 1, z + 1/2; (iii) ...
Fig. 2.
A view of the crystal packing in (I) projected down the b axis. Hydrogen bonds are drawn as dashed lines and coordinate bonds to the Ba centers are omitted for clarity.

Crystal data

[BaCu(C2O4)2(H2O)5]·H2OF000 = 1864
Mr = 485.02Dx = 2.500 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3213 reflections
a = 15.744 (2) Åθ = 2.3–28.3º
b = 10.7565 (15) ŵ = 4.76 mm1
c = 15.345 (2) ÅT = 293 (2) K
β = 97.331 (2)ºPrism, blue
V = 2577.5 (6) Å30.28 × 0.14 × 0.10 mm
Z = 8

Data collection

Bruker APEX CCD area detector diffractometer3213 independent reflections
Radiation source: fine-focus sealed tube3180 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.022
T = 293(2) Kθmax = 28.3º
ω & [var phi] scansθmin = 2.3º
Absorption correction: multi-scan(SADABS; Bruker, 2001)h = −20→20
Tmin = 0.462, Tmax = 0.631k = −14→14
17321 measured reflectionsl = −20→20

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.020All H-atom parameters refined
wR(F2) = 0.050  w = 1/[σ2(Fo2) + (0.0219P)2 + 2.8035P] where P = (Fo2 + 2Fc2)/3
S = 1.32(Δ/σ)max < 0.001
3213 reflectionsΔρmax = 0.49 e Å3
228 parametersΔρmin = −1.00 e Å3
12 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods

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 (Å2)

xyzUiso*/Ueq
Ba0.141583 (8)0.466998 (11)0.208698 (8)0.01861 (5)
Cu0.392694 (18)0.57358 (3)0.044543 (18)0.02206 (7)
O10.32532 (11)0.68548 (15)−0.03636 (11)0.0259 (3)
O20.32797 (11)0.44372 (15)−0.02082 (11)0.0246 (3)
O30.46519 (11)0.70211 (15)0.10073 (11)0.0253 (3)
O40.47712 (11)0.45898 (14)0.10183 (12)0.0265 (4)
O50.59239 (11)0.46396 (15)0.20210 (12)0.0269 (4)
O60.23179 (11)0.57822 (15)0.36098 (11)0.0266 (3)
O70.23098 (12)0.32494 (15)0.34220 (12)0.0297 (4)
O80.08384 (11)0.22003 (16)0.19560 (12)0.0286 (4)
C10.27787 (14)0.4853 (2)−0.08588 (15)0.0191 (4)
C20.52919 (14)0.6586 (2)0.15113 (14)0.0201 (4)
C30.53447 (14)0.5145 (2)0.15330 (15)0.0195 (4)
C40.27694 (14)0.6281 (2)−0.09552 (15)0.0201 (4)
O100.29911 (11)0.57403 (16)0.16050 (12)0.0251 (3)
O110.21699 (14)0.32422 (18)0.09118 (15)0.0383 (5)
O120.09995 (15)0.58277 (19)0.04541 (13)0.0363 (4)
O130.09098 (17)0.7070 (2)0.24223 (18)0.0485 (6)
O14−0.06779 (16)0.6935 (2)0.05515 (17)0.0482 (5)
O150.03947 (12)0.45626 (19)0.34874 (13)0.0290 (4)
H10A0.287 (2)0.648 (2)0.166 (2)0.041 (9)*
H10B0.332 (2)0.557 (3)0.2032 (19)0.042 (10)*
H11A0.257 (2)0.351 (4)0.069 (2)0.053 (11)*
H11B0.237 (2)0.254 (3)0.106 (3)0.061 (12)*
H12A0.129 (2)0.643 (3)0.040 (2)0.046 (10)*
H12B0.0539 (18)0.611 (4)0.043 (3)0.056 (12)*
H13A0.097 (4)0.779 (3)0.226 (4)0.104 (14)*
H13B0.078 (3)0.721 (5)0.291 (2)0.104 (14)*
H14A−0.106 (2)0.697 (4)0.016 (2)0.069 (14)*
H14B−0.047 (3)0.764 (3)0.061 (3)0.091 (17)*
H15A0.047 (2)0.386 (3)0.368 (2)0.051 (11)*
H15B0.059 (3)0.506 (4)0.381 (3)0.066 (14)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Ba0.01904 (8)0.01779 (7)0.01834 (8)−0.00038 (4)−0.00019 (5)0.00062 (4)
Cu0.02429 (14)0.01650 (13)0.02248 (14)−0.00159 (10)−0.00821 (10)−0.00040 (10)
O10.0300 (8)0.0164 (7)0.0279 (8)−0.0009 (6)−0.0089 (7)−0.0011 (6)
O20.0303 (9)0.0172 (7)0.0234 (8)−0.0024 (6)−0.0086 (7)0.0024 (6)
O30.0263 (8)0.0181 (7)0.0286 (8)−0.0022 (6)−0.0071 (6)−0.0001 (6)
O40.0285 (9)0.0182 (7)0.0294 (9)0.0000 (6)−0.0090 (7)−0.0023 (6)
O50.0244 (8)0.0235 (8)0.0302 (9)0.0007 (6)−0.0059 (7)0.0022 (6)
O60.0294 (8)0.0197 (8)0.0275 (8)0.0049 (6)−0.0090 (7)0.0004 (6)
O70.0349 (9)0.0191 (8)0.0307 (9)−0.0022 (7)−0.0132 (7)−0.0014 (7)
O80.0256 (8)0.0252 (8)0.0328 (9)−0.0071 (7)−0.0053 (7)−0.0035 (7)
C10.0189 (9)0.0173 (9)0.0208 (10)−0.0010 (7)0.0009 (8)0.0002 (8)
C20.0215 (10)0.0193 (10)0.0194 (10)−0.0025 (8)0.0023 (8)−0.0002 (8)
C30.0206 (10)0.0189 (10)0.0190 (10)−0.0006 (8)0.0026 (8)0.0001 (8)
C40.0204 (10)0.0162 (9)0.0228 (10)0.0003 (7)−0.0003 (8)0.0008 (8)
O100.0253 (8)0.0215 (8)0.0266 (8)0.0002 (7)−0.0044 (7)−0.0004 (7)
O110.0501 (12)0.0192 (8)0.0503 (12)−0.0010 (8)0.0250 (10)−0.0001 (8)
O120.0451 (12)0.0278 (10)0.0344 (10)−0.0054 (9)−0.0014 (9)0.0072 (8)
O130.0605 (15)0.0242 (10)0.0625 (15)0.0077 (10)0.0139 (12)0.0060 (10)
O140.0460 (13)0.0465 (13)0.0501 (14)−0.0039 (11)−0.0018 (11)0.0160 (11)
O150.0263 (9)0.0353 (10)0.0245 (9)−0.0004 (7)−0.0005 (7)0.0006 (8)

Geometric parameters (Å, °)

Ba—O112.751 (2)O7—C4ii1.231 (3)
Ba—O132.770 (2)O8—C2iii1.222 (3)
Ba—O72.7888 (17)C1—O6iv1.228 (3)
Ba—O122.800 (2)C1—C41.542 (3)
Ba—O82.8066 (17)C2—O8v1.222 (3)
Ba—O62.8393 (17)C2—C31.552 (3)
Ba—O152.846 (2)C4—O7iv1.231 (3)
Ba—O15i2.8765 (19)O10—H10A0.82 (2)
Ba—O102.9140 (18)O10—H10B0.80 (2)
Ba—Bai4.7880 (7)O11—H11A0.80 (2)
Cu—O31.9252 (16)O11—H11B0.84 (3)
Cu—O21.9326 (16)O12—H12A0.80 (2)
Cu—O41.9393 (17)O12—H12B0.78 (2)
Cu—O11.9440 (16)O13—H13A0.82 (3)
Cu—O102.451 (3)O13—H13B0.81 (3)
O1—C41.269 (3)O14—H14A0.80 (3)
O2—C11.272 (3)O14—H14B0.83 (3)
O3—C21.278 (3)O15—Bai2.8765 (19)
O4—C31.270 (3)O15—H15A0.81 (2)
O5—C31.230 (3)O15—H15B0.76 (3)
O6—C1ii1.228 (3)
O11—Ba—O13143.20 (7)O3—Cu—O2174.10 (8)
O11—Ba—O787.48 (6)O3—Cu—O485.44 (7)
O13—Ba—O7120.30 (7)O2—Cu—O493.52 (7)
O11—Ba—O1274.52 (7)O3—Cu—O194.90 (7)
O13—Ba—O1273.24 (7)O2—Cu—O184.69 (7)
O7—Ba—O12160.00 (6)O4—Cu—O1165.84 (8)
O11—Ba—O865.64 (6)O4—Cu—O1096.48 (7)
O13—Ba—O8142.89 (7)C4—O1—Cu112.60 (14)
O7—Ba—O870.27 (5)C1—O2—Cu112.70 (14)
O12—Ba—O8108.68 (6)C2—O3—Cu112.62 (14)
O11—Ba—O6124.22 (6)C3—O4—Cu112.01 (14)
O13—Ba—O665.15 (7)C1ii—O6—Ba120.20 (14)
O7—Ba—O658.25 (5)C4ii—O7—Ba122.45 (14)
O12—Ba—O6125.77 (6)C2iii—O8—Ba138.63 (15)
O8—Ba—O6125.53 (5)O6iv—C1—O2125.4 (2)
O11—Ba—O15143.62 (6)O6iv—C1—C4119.5 (2)
O13—Ba—O1572.18 (7)O2—C1—C4115.03 (19)
O7—Ba—O1572.77 (6)O8v—C2—O3125.8 (2)
O12—Ba—O15127.12 (6)O8v—C2—C3119.7 (2)
O8—Ba—O1578.85 (6)O3—C2—C3114.49 (18)
O6—Ba—O1570.55 (6)O5—C3—O4125.7 (2)
O11—Ba—O15i105.69 (6)O5—C3—C2119.2 (2)
O13—Ba—O15i78.29 (7)O4—C3—C2115.09 (19)
O7—Ba—O15i126.20 (6)O7iv—C4—O1126.5 (2)
O12—Ba—O15i68.53 (6)O7iv—C4—C1118.73 (19)
O8—Ba—O15i68.95 (5)O1—C4—C1114.74 (19)
O6—Ba—O15i129.88 (5)Ba—O10—H10A98 (2)
O15—Ba—O15i66.20 (6)Ba—O10—H10B101 (3)
O11—Ba—O1066.53 (6)H10A—O10—H10B105 (3)
O13—Ba—O1087.32 (6)Ba—O11—H11A120 (3)
O7—Ba—O1092.11 (5)Ba—O11—H11B120 (3)
O12—Ba—O1072.95 (6)H11A—O11—H11B98 (4)
O8—Ba—O10129.36 (5)Ba—O12—H12A113 (3)
O6—Ba—O1071.93 (5)Ba—O12—H12B109 (3)
O15—Ba—O10142.08 (5)H12A—O12—H12B103 (4)
O15i—Ba—O10141.29 (5)Ba—O13—H13A141 (4)
O11—Ba—Bai131.91 (5)Ba—O13—H13B117 (4)
O13—Ba—Bai69.58 (5)H13A—O13—H13B99 (5)
O7—Ba—Bai101.84 (4)H14A—O14—H14B106 (5)
O12—Ba—Bai96.74 (5)Ba—O15—Bai113.60 (6)
O8—Ba—Bai73.44 (4)Ba—O15—H15A104 (3)
O6—Ba—Bai99.61 (4)Bai—O15—H15A104 (3)
O15—Ba—Bai33.40 (4)Ba—O15—H15B104 (4)
O15i—Ba—Bai33.00 (4)Bai—O15—H15B118 (4)
O10—Ba—Bai156.72 (3)H15A—O15—H15B113 (4)

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

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O10—H10A···O7vi0.82 (2)1.93 (2)2.740 (2)168 (3)
O10—H10B···O5vii0.80 (2)2.02 (3)2.801 (2)163 (4)
O10—H10B···O8vi0.80 (2)2.59 (3)3.114 (2)125 (3)
O11—H11A···O20.80 (2)2.13 (3)2.903 (3)161 (4)
O11—H11B···O6viii0.84 (3)2.00 (3)2.835 (3)172 (4)
O11—H11B···O2ix0.84 (3)2.63 (4)3.127 (3)119 (3)
O12—H12A···O1x0.80 (2)1.98 (3)2.768 (3)165 (4)
O13—H13A···O5xi0.82 (3)2.02 (3)2.832 (3)168 (6)
O13—H13B···O14i0.81 (3)2.41 (3)3.180 (4)159 (6)
O14—H14A···O11xii0.80 (3)2.25 (3)3.041 (3)171 (5)
O14—H14B···O4xi0.83 (3)2.21 (3)3.007 (3)163 (5)
O15—H15A···O3viii0.81 (2)2.05 (3)2.845 (3)165 (4)
O12—H12B···O140.78 (2)2.14 (3)2.918 (3)173 (4)
O15—H15B···O14i0.76 (3)2.24 (3)2.952 (3)156 (5)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2219).

References

  • Belombe, M. M., Nenwa, J., Bebga, G., Fokwa, B. P. T. & Dronskowski, R. (2007). Acta Cryst. E63, m2037–m2038.
  • Bélombé, M. M., Nenwa, J., Fokwa, B. P. & Dronskowski, R. (2006). Acta Cryst. E62, m1400–m1402.
  • Bélombé, M. M., Nenwa, J., Mbiangué, Y.-A., Gouet Bebga, Majoumo-Mbé, F., Hey-Hawkins, E. & Lönnecke, P. (2007). Inorg. Chim. Acta doi: 10.1016/j.ica.2007.03.003.
  • Bélombé, M. M., Nenwa, J., Mbiangué, Y.-A., Nnanga, G. E., Mbomekallé, I.-M., Hey-Hawkins, E., Lönnecke, P. & Majoumo, F. (2003). Dalton Trans. pp. 2117–2118.
  • Bouayad, A., Trobe, J.-C. & Gleizes, A. (1995). Inorg. Chim. Acta, 230, 1–7.
  • Brandenburg, K. (1999). DIAMOND Release 2.1c. Crystal Impact, Bonn, Germany.
  • Bruker (1998). SMART Version 5.624a. Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2000). SAINT Version 6.02a. Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2001). SADABS (Version 2.03) and SHELXTL (Version 6.12). Bruker AXS Inc., Madison, Wisconsin, USA.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Kirschner, S. (1960). Inorg. Synth.6, 1–2.
  • Nenwa, J. (2004). PhD dissertation, University of Yaounde I, Cameroon.
  • Sheldrick, G. M. (1997). SHELXS97 and SHELXL97 University of Göttingen, Germany.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography