supplementary materials


Acta Cryst. (2009). E65, m1164    [ doi:10.1107/S1600536809035089 ]

catena-Poly[[aqua(1,10-phenanthroline)cobalt(II)]-[mu]-4,4'-(propane-1,3-diyldioxy)dibenzoato]

S.-M. Shen

Abstract top

In the title compound, [Co(C17H14O6)(C12H8N2)(H2O)]n, the CoII atom is coordinated by a monodentate 4,4'-(propane-1,3-diyldioxy)dibenzoate (cpp) dianion, a water molecule and a chelating 1,10-phenanthroline (phen) ligand. A symmetry-generated cpp ligand completes the CoN2O3 trigonal-bipyramidal geometry for the metal ion, with the N atoms occupying both equatorial and axial sites. The bridging cpp ligands form chains propagating in [110] and O-H...O hydrogen bonds consolidate the packing.

Comment top

Design of effective ligands and the proper choice of metal centers are the keys to design and construct novel metal-organic frameworks (Kitagawa et al., 2004; Schokecht & Kempe, 2004). Polycarboxylate ligands have received considerable attention, owing to the variety of their coordination modes and structural features. 4,4'-(propane-1,3-diyldioxy)dibenzoic acid (H2cpp) is a potential multi-dentate ligand with a versatile coordination mode, which has been used in self-asssembled porous coordination synthesis (Liu et al., 2009).

The title compound, (I), was constructed by two kinds of bridging and chelating ligands under mild condition, H2cpp and phen which were self-assembled to a one-dimensional neutral metal-organic compound. In this paper, the crystal structure of (I) is presented.

As illustrated in Fig. 1, CoII adopts a trigonal bispyramidal geometry, generated by three O atoms from two adjacent monodenated-chelating carboxylate groups and one coordinated water molecule, and two N atoms from one chelating phen ligand. The three atoms (O1, O1W and N3) in the basical plane around the Co atom, while the other two atoms (O6 and N4) locate at apical positions. The twist angle of two rings of cpp ligand is 96.8 (5)°.

The neighboring Co atoms are linked by cp ligands forming a one-dimensional chain running along a axis (Fig. 2). These chains are decorated with phen ligands alternating on two sides, which is similar with some complexes (Chen & Liu, 2002) There are no π-π interactions between rings of phen ligands due to its transplacement arrangement.

In the crystal structure, strong intermolecular O-H···O hydrogen bonds (Table 1) link the molecules into a 2D network, in which they may be effective in the stabilization of the structure.

Related literature top

For a related structure, see: Chen & Liu (2002). For background to metal-organic frameworks, see: Kitagawa et al. (2004); Liu et al. (2009); Schokecht & Kempe (2004).

Experimental top

The followinf quantities were mixed: (23 mg, 0.1 mmol)) Co(NO3)2 of water solution (5 ml) and H2CP (26 mg, 0.1 mmol), phen (0.19 mg, 0.1 mmol) and NaOH (3.8 mg, 0.09 mmol), CH3CN (5 ml) and heated to at 428 K for 60 h in a pressurized reactor. Slow evaporation of this solution resulted in the formation of some pink blocks of (I).

Refinement top

All H atoms attached to C atoms were fixed geometrically and treated as riding with C—H = 0.93 Å (aromatic) with Uiso(H) = 1.2Ueq(C). H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O-H = 0.84 (2)Å and H···H = 1.38 (2)Å) with Uiso(H) = 1.5Ueq(O). The highest residual difference electron-density peak is 1.50Å from N3.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. View of a fragment of (I). Ellipsoids are drawn at the the 30% probability level. H atomsare shown as spheres of arbitrary radii. [symmetry codes: (i) x-1, y-1, z; (ii) 1+x, y+1, 3+z]
[Figure 2] Fig. 2. Partial packing of (I) showing the formation of a chain along c axis.
catena-Poly[[aqua(1,10-phenanthroline)cobalt(II)]-µ-4,4'-(propane- 1,3-diyldioxy)dibenzoato] top
Crystal data top
[Co(C17H14O6)(C12H8N2)(H2O)]Z = 2
Mr = 571.43F(000) = 590
Triclinic, P1Dx = 1.496 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.5967 (17) ÅCell parameters from 4499 reflections
b = 11.432 (2) Åθ = 1.5–25.2°
c = 14.423 (3) ŵ = 0.73 mm1
α = 68.433 (3)°T = 298 K
β = 87.673 (4)°Block, pink
γ = 74.635 (4)°0.23 × 0.14 × 0.11 mm
V = 1268.5 (4) Å3
Data collection top
Bruker APEXII area-detector
diffractometer
4499 independent reflections
Radiation source: fine-focus sealed tube2242 reflections with I > 2σ(I)
graphiteRint = 0.032
φ and ω scansθmax = 25.2°, θmin = 1.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 108
Tmin = 0.850, Tmax = 0.924k = 1113
6503 measured reflectionsl = 1717
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.063H atoms treated by a mixture of independent and constrained refinement
S = 0.91 w = 1/[σ2(Fo2) + (0.01P)2 + 0.001P]
where P = (Fo2 + 2Fc2)/3
4499 reflections(Δ/σ)max < 0.001
358 parametersΔρmax = 0.19 e Å3
3 restraintsΔρmin = 0.21 e Å3
Crystal data top
[Co(C17H14O6)(C12H8N2)(H2O)]γ = 74.635 (4)°
Mr = 571.43V = 1268.5 (4) Å3
Triclinic, P1Z = 2
a = 8.5967 (17) ÅMo Kα radiation
b = 11.432 (2) ŵ = 0.73 mm1
c = 14.423 (3) ÅT = 298 K
α = 68.433 (3)°0.23 × 0.14 × 0.11 mm
β = 87.673 (4)°
Data collection top
Bruker APEXII area-detector
diffractometer
4499 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
2242 reflections with I > 2σ(I)
Tmin = 0.850, Tmax = 0.924Rint = 0.032
6503 measured reflectionsθmax = 25.2°
Refinement top
R[F2 > 2σ(F2)] = 0.039H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.063Δρmax = 0.19 e Å3
S = 0.91Δρmin = 0.21 e Å3
4499 reflectionsAbsolute structure: ?
358 parametersFlack parameter: ?
3 restraintsRogers parameter: ?
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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) top
xyzUiso*/Ueq
Co10.63053 (6)0.14519 (4)0.37254 (3)0.04796 (15)
O10.6918 (3)0.01199 (17)0.26875 (13)0.0552 (6)
O20.5285 (3)0.08365 (17)0.36879 (14)0.0568 (6)
O61.4634 (3)0.84914 (19)0.28126 (14)0.0557 (6)
O51.2435 (3)0.91935 (18)0.35373 (14)0.0599 (6)
O30.6256 (3)0.62108 (18)0.06262 (15)0.0663 (7)
O40.9367 (3)0.79789 (19)0.01759 (15)0.0645 (7)
O1W0.4880 (3)0.19495 (18)0.49172 (15)0.0547 (6)
N30.8001 (3)0.2965 (2)0.34395 (17)0.0459 (7)
N40.8312 (3)0.1855 (2)0.47342 (16)0.0479 (7)
C50.6272 (4)0.4931 (3)0.1143 (2)0.0478 (9)
C151.2806 (4)0.8073 (2)0.14796 (19)0.0446 (8)
H151.39260.78000.14810.053*
C20.6156 (4)0.2400 (3)0.23088 (19)0.0372 (8)
C171.3121 (5)0.8825 (3)0.2871 (2)0.0442 (9)
C141.2101 (4)0.8686 (2)0.21218 (19)0.0388 (8)
C111.0202 (5)0.8281 (3)0.0810 (2)0.0466 (9)
C220.9490 (4)0.3320 (3)0.3897 (2)0.0431 (8)
C10.6105 (4)0.1044 (3)0.2937 (2)0.0449 (9)
C161.1861 (5)0.7864 (3)0.0841 (2)0.0513 (9)
H161.23490.74350.04240.062*
C131.0445 (4)0.9135 (2)0.2059 (2)0.0428 (8)
H130.99590.95740.24690.051*
C230.9660 (4)0.2726 (3)0.4596 (2)0.0427 (8)
C201.0562 (5)0.4759 (3)0.3037 (2)0.0574 (10)
H201.14100.53480.28880.069*
C120.9468 (4)0.8959 (2)0.1406 (2)0.0462 (8)
H120.83500.92870.13700.055*
C70.7238 (4)0.2625 (3)0.1578 (2)0.0491 (9)
H70.79390.19180.14730.059*
C180.7807 (4)0.3527 (3)0.2806 (2)0.0516 (9)
H180.67870.33140.24980.062*
C40.5183 (4)0.4717 (3)0.1876 (2)0.0517 (9)
H40.44800.54220.19830.062*
C60.7314 (4)0.3883 (3)0.0993 (2)0.0536 (10)
H60.80610.40130.05060.064*
C30.5132 (4)0.3464 (3)0.2450 (2)0.0473 (9)
H30.43930.33340.29410.057*
C211.0827 (4)0.4225 (3)0.3726 (2)0.0454 (8)
C290.8459 (4)0.1330 (3)0.5391 (2)0.0566 (10)
H290.75560.07370.54890.068*
C261.1150 (4)0.3060 (3)0.5110 (2)0.0494 (9)
C241.2331 (4)0.4527 (3)0.4262 (2)0.0606 (10)
H241.32250.51200.41540.073*
C90.7016 (4)0.7961 (3)0.0633 (2)0.0729 (12)
H9A0.58690.83830.07870.088*
H9B0.75510.81910.12550.088*
C190.9069 (5)0.4420 (3)0.2586 (2)0.0596 (10)
H190.88880.47810.21320.072*
C80.7272 (4)0.6493 (3)0.0194 (2)0.0680 (11)
H8A0.69890.61910.06950.082*
H8B0.83960.60560.00350.082*
C271.1243 (4)0.2470 (3)0.5802 (2)0.0615 (10)
H271.22130.26610.61590.074*
C280.9895 (5)0.1616 (3)0.5944 (2)0.0635 (10)
H280.99350.12290.64050.076*
C251.2484 (4)0.3972 (3)0.4922 (2)0.0581 (9)
H251.34810.41890.52590.070*
C100.7656 (5)0.8476 (3)0.0062 (2)0.0634 (10)
H10A0.73590.94230.02170.076*
H10B0.71960.81950.07060.076*
H1WA0.399 (3)0.145 (3)0.453 (2)0.095*
H1WB0.482 (4)0.163 (3)0.5397 (16)0.095*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Co10.0490 (4)0.0497 (3)0.0462 (3)0.0154 (2)0.0012 (2)0.0169 (2)
O10.0598 (18)0.0395 (13)0.0671 (15)0.0094 (11)0.0061 (12)0.0235 (11)
O20.072 (2)0.0588 (14)0.0454 (14)0.0295 (12)0.0080 (12)0.0181 (11)
O60.0438 (18)0.0788 (16)0.0523 (14)0.0163 (13)0.0046 (13)0.0324 (12)
O50.0539 (18)0.0800 (16)0.0604 (15)0.0118 (12)0.0031 (12)0.0462 (13)
O30.085 (2)0.0444 (14)0.0696 (16)0.0252 (13)0.0050 (14)0.0151 (12)
O40.079 (2)0.0670 (15)0.0612 (15)0.0276 (15)0.0163 (14)0.0321 (12)
O1W0.064 (2)0.0617 (15)0.0437 (14)0.0218 (12)0.0013 (11)0.0222 (12)
N30.053 (2)0.0458 (16)0.0438 (16)0.0165 (14)0.0043 (15)0.0190 (13)
N40.057 (2)0.0510 (16)0.0426 (16)0.0185 (15)0.0054 (14)0.0218 (13)
C50.062 (3)0.036 (2)0.047 (2)0.0167 (19)0.0113 (19)0.0136 (17)
C150.048 (3)0.0424 (18)0.0453 (19)0.0145 (16)0.0018 (18)0.0170 (16)
C20.044 (2)0.0402 (19)0.0331 (18)0.0136 (17)0.0008 (16)0.0176 (15)
C170.053 (3)0.0387 (19)0.043 (2)0.0141 (18)0.000 (2)0.0160 (16)
C140.051 (3)0.0331 (17)0.0341 (18)0.0136 (17)0.0003 (17)0.0125 (14)
C110.063 (3)0.0393 (19)0.042 (2)0.0215 (19)0.0062 (19)0.0131 (16)
C220.049 (3)0.0407 (19)0.040 (2)0.0205 (18)0.0011 (18)0.0100 (16)
C10.048 (3)0.045 (2)0.048 (2)0.0173 (18)0.0128 (18)0.0192 (18)
C160.061 (3)0.049 (2)0.052 (2)0.012 (2)0.001 (2)0.0296 (17)
C130.049 (3)0.0384 (18)0.045 (2)0.0107 (17)0.0005 (18)0.0202 (15)
C230.045 (3)0.046 (2)0.038 (2)0.0179 (18)0.0025 (18)0.0128 (16)
C200.060 (3)0.052 (2)0.058 (2)0.008 (2)0.001 (2)0.0235 (18)
C120.047 (3)0.0418 (19)0.049 (2)0.0120 (16)0.0071 (18)0.0146 (16)
C70.067 (3)0.043 (2)0.047 (2)0.0169 (18)0.0029 (19)0.0259 (17)
C180.063 (3)0.051 (2)0.046 (2)0.0232 (19)0.0024 (18)0.0167 (17)
C40.049 (3)0.040 (2)0.067 (2)0.0037 (17)0.0044 (19)0.0248 (18)
C60.080 (3)0.049 (2)0.043 (2)0.030 (2)0.0109 (19)0.0209 (17)
C30.047 (3)0.048 (2)0.047 (2)0.0140 (18)0.0013 (17)0.0169 (17)
C210.045 (3)0.044 (2)0.048 (2)0.0119 (18)0.0055 (19)0.0169 (16)
C290.062 (3)0.056 (2)0.059 (2)0.0123 (19)0.003 (2)0.0311 (18)
C260.044 (3)0.048 (2)0.056 (2)0.0140 (18)0.0012 (19)0.0179 (17)
C240.048 (3)0.051 (2)0.078 (3)0.0065 (18)0.001 (2)0.0237 (19)
C90.110 (4)0.060 (2)0.051 (2)0.047 (2)0.029 (2)0.0032 (18)
C190.071 (3)0.060 (2)0.056 (2)0.016 (2)0.001 (2)0.0324 (19)
C80.107 (4)0.056 (2)0.051 (2)0.044 (2)0.010 (2)0.0138 (18)
C270.062 (3)0.071 (2)0.059 (2)0.025 (2)0.015 (2)0.024 (2)
C280.061 (3)0.071 (3)0.070 (3)0.016 (2)0.015 (2)0.040 (2)
C250.042 (3)0.062 (2)0.071 (2)0.0132 (19)0.0098 (19)0.024 (2)
C100.082 (4)0.050 (2)0.055 (2)0.026 (2)0.023 (2)0.0072 (17)
Geometric parameters (Å, °) top
Co1—O6i2.017 (2)C13—C121.387 (4)
Co1—O12.0511 (17)C13—H130.9300
Co1—O1W2.063 (2)C23—C261.395 (4)
Co1—N32.104 (2)C20—C191.357 (4)
Co1—N42.143 (2)C20—C211.396 (4)
O1—C11.265 (3)C20—H200.9300
O2—C11.251 (3)C12—H120.9300
O6—C171.263 (3)C7—C61.392 (3)
O6—Co1ii2.017 (2)C7—H70.9300
O5—C171.253 (3)C18—C191.394 (4)
O3—C51.373 (3)C18—H180.9300
O3—C81.432 (3)C4—C31.377 (3)
O4—C111.374 (3)C4—H40.9300
O4—C101.421 (4)C6—H60.9300
O1W—H1WA0.885 (17)C3—H30.9300
O1W—H1WB0.885 (15)C21—C241.427 (4)
N3—C181.332 (3)C29—C281.393 (4)
N3—C221.354 (4)C29—H290.9300
N4—C291.319 (3)C26—C271.409 (3)
N4—C231.374 (3)C26—C251.423 (4)
C5—C61.375 (4)C24—C251.352 (3)
C5—C41.381 (3)C24—H240.9300
C15—C161.376 (4)C9—C81.517 (3)
C15—C141.387 (3)C9—C101.518 (3)
C15—H150.9300C9—H9A0.9700
C2—C71.374 (3)C9—H9B0.9700
C2—C31.376 (3)C19—H190.9300
C2—C11.493 (3)C8—H8A0.9700
C17—C141.496 (4)C8—H8B0.9700
C14—C131.374 (4)C27—C281.366 (4)
C11—C161.375 (4)C27—H270.9300
C11—C121.388 (3)C28—H280.9300
C22—C211.409 (4)C25—H250.9300
C22—C231.439 (3)C10—H10A0.9700
C16—H160.9300C10—H10B0.9700
O6i—Co1—O195.13 (8)C13—C12—H12120.9
O6i—Co1—O1W90.40 (9)C11—C12—H12120.9
O1—Co1—O1W142.18 (7)C2—C7—C6121.8 (3)
O6i—Co1—N390.17 (10)C2—C7—H7119.1
O1—Co1—N399.18 (8)C6—C7—H7119.1
O1W—Co1—N3118.22 (8)N3—C18—C19122.8 (3)
O6i—Co1—N4166.69 (9)N3—C18—H18118.6
O1—Co1—N492.61 (8)C19—C18—H18118.6
O1W—Co1—N490.10 (9)C3—C4—C5120.3 (3)
N3—Co1—N477.90 (10)C3—C4—H4119.8
C1—O1—Co1101.40 (18)C5—C4—H4119.8
C17—O6—Co1ii125.76 (19)C5—C6—C7119.2 (3)
C5—O3—C8118.2 (2)C5—C6—H6120.4
C11—O4—C10118.3 (2)C7—C6—H6120.4
Co1—O1W—H1WA91 (2)C2—C3—C4121.2 (3)
Co1—O1W—H1WB122.6 (19)C2—C3—H3119.4
H1WA—O1W—H1WB103 (2)C4—C3—H3119.4
C18—N3—C22117.3 (3)C20—C21—C22116.5 (3)
C18—N3—Co1127.3 (2)C20—C21—C24125.1 (3)
C22—N3—Co1115.16 (19)C22—C21—C24118.3 (3)
C29—N4—C23117.4 (3)N4—C29—C28123.5 (3)
C29—N4—Co1129.9 (2)N4—C29—H29118.3
C23—N4—Co1112.55 (19)C28—C29—H29118.3
O3—C5—C6124.4 (3)C23—C26—C27117.3 (3)
O3—C5—C4116.0 (3)C23—C26—C25119.3 (3)
C6—C5—C4119.5 (3)C27—C26—C25123.4 (4)
C16—C15—C14120.5 (3)C25—C24—C21121.4 (3)
C16—C15—H15119.8C25—C24—H24119.3
C14—C15—H15119.8C21—C24—H24119.3
C7—C2—C3118.0 (3)C8—C9—C10113.0 (2)
C7—C2—C1121.0 (3)C8—C9—H9A109.0
C3—C2—C1121.0 (3)C10—C9—H9A109.0
O5—C17—O6124.6 (3)C8—C9—H9B109.0
O5—C17—C14118.5 (3)C10—C9—H9B109.0
O6—C17—C14116.8 (3)H9A—C9—H9B107.8
C13—C14—C15117.9 (3)C20—C19—C18119.7 (3)
C13—C14—C17121.5 (3)C20—C19—H19120.2
C15—C14—C17120.6 (3)C18—C19—H19120.2
O4—C11—C16116.4 (3)O3—C8—C9107.4 (3)
O4—C11—C12123.8 (3)O3—C8—H8A110.2
C16—C11—C12119.8 (3)C9—C8—H8A110.2
N3—C22—C21123.7 (3)O3—C8—H8B110.2
N3—C22—C23116.3 (3)C9—C8—H8B110.2
C21—C22—C23120.1 (3)H8A—C8—H8B108.5
O2—C1—O1121.5 (3)C28—C27—C26119.4 (3)
O2—C1—C2120.5 (3)C28—C27—H27120.3
O1—C1—C2118.0 (3)C26—C27—H27120.3
C11—C16—C15120.9 (3)C27—C28—C29119.3 (3)
C11—C16—H16119.6C27—C28—H28120.3
C15—C16—H16119.6C29—C28—H28120.3
C14—C13—C12122.6 (3)C24—C25—C26121.3 (3)
C14—C13—H13118.7C24—C25—H25119.4
C12—C13—H13118.7C26—C25—H25119.4
N4—C23—C26123.0 (3)O4—C10—C9108.3 (3)
N4—C23—C22117.4 (3)O4—C10—H10A110.0
C26—C23—C22119.6 (3)C9—C10—H10A110.0
C19—C20—C21120.1 (3)O4—C10—H10B110.0
C19—C20—H20120.0C9—C10—H10B110.0
C21—C20—H20120.0H10A—C10—H10B108.4
C13—C12—C11118.2 (3)
Symmetry codes: (i) x−1, y−1, z; (ii) x+1, y+1, z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O2iii0.89 (2)1.85 (2)2.729 (3)175 (3)
O1W—H1WA···O5i0.89 (2)1.80 (2)2.657 (3)161 (3)
Symmetry codes: (iii) −x+1, −y, −z+1; (i) x−1, y−1, z.
Table 1
Hydrogen-bond geometry (Å, °)
top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O2i0.89 (2)1.85 (2)2.729 (3)175 (3)
O1W—H1WA···O5ii0.89 (2)1.80 (2)2.657 (3)161 (3)
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x−1, y−1, z.
Acknowledgements top

The authors are grateful to the Zhejiang Economic and Trade Polytechnic for financial support.

references
References top

Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.

Chen, X. M. & Liu, G. F. (2002). Chem. Eur. J. 8, 4811–4817.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Kitagawa, S., Kitaura, R. & Noro, S. (2004). Angew. Chem. Int. Ed. 43, 2334–2375.

Liu, J. Q., Wang, Y. Y., Liu, P., Dong, Z., Shi, Q. Z. & Batten, S. R. (2009). CrystEngComm, 11, 1207–1209.

Schokecht, B. & Kempe, R. (2004). Z. Anorg. Allg. Chem. 630, 1377–1379.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.