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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): m1340.
Published online 2009 October 10. doi:  10.1107/S1600536809040549
PMCID: PMC2971300

Bis[N-(2-pyridylcarbon­yl)pyridine-2-carboximidato]iron(III) perchlorate methanol solvate

Abstract

In the title complex, [Fe(C12H8N3O2)2]ClO4·CH3OH, the iron(III) ion is surrounded by two tridentate N-(2-pyridyl­carbon­yl)pyridine-2-carboximidate (bpca) ligands and exhib­its a distorted octa­hedral coordination by six bpca N atoms. A classical O—H(...)O hydrogen bond exists between the methanol solvent mol­ecule and the perchlorate anion. Magnetic susceptibility measurements indicated the complex to be in the low-spin state in the temperature range 5–400 K.

Related literature

For the structure and magnetic properties of methanol-free [Fe(bpca)2]ClO4 and related compounds, see: Wocadlo et al. (1993 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-m1340-scheme1.jpg

Experimental

Crystal data

  • [Fe(C12H8N3O2)2]ClO4·CH4O
  • M r = 639.77
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-m1340-efi1.jpg
  • a = 8.799 (3) Å
  • b = 11.603 (4) Å
  • c = 14.356 (6) Å
  • α = 109.507 (4)°
  • β = 103.394 (3)°
  • γ = 100.091 (3)°
  • V = 1292.0 (8) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.76 mm−1
  • T = 143 K
  • 0.32 × 0.26 × 0.23 mm

Data collection

  • Bruker SMART APEX CCD area-detector diffractometer
  • Absorption correction: multi-scan(SHELXTL; Sheldrick, 2008 [triangle]) T min = 0.790, T max = 0.840
  • 8499 measured reflections
  • 4421 independent reflections
  • 4177 reflections with I > 2σ(I)
  • R int = 0.040

Refinement

  • R[F 2 > 2σ(F 2)] = 0.040
  • wR(F 2) = 0.107
  • S = 1.03
  • 4421 reflections
  • 379 parameters
  • H-atom parameters constrained
  • Δρmax = 1.48 e Å−3
  • Δρmin = −0.48 e Å−3

Data collection: SMART (Bruker, 1997 [triangle]); cell refinement: SAINT (Bruker, 1997 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 [triangle]).

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

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809040549/si2207sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809040549/si2207Isup2.hkl

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

supplementary crystallographic information

Comment

Our recent work indicated the N-donor tridentate ligand is suitable for the synthesis of spin-crossover materials. The N-2-pyridinylcarbonyl-2-pyridinecarboximidate (bpca) ligand has a typical rigid tridentate donor and was well studied to construct transition metal complexes inculding Fe(II), Fe(III), Co(II), Ni(II) and Cu(II) (Wocadlo et al. 1993 and references cited therein).. One of the examples is reported by Wocadlo and coworkers, which interestingly showed the spin state can be tuned by the different counterion and solvent. It was claimed that Fe(III) complex [Fe(bpca)Cl2(H2O)] (CH3)2CO and [Fe(bpca)2](NO3) 1.67 H2O adopt high spin state and the low-spin one in all the range of measured temperatures, respectively, while the [Fe(bpca)2](C1O4) evidence the spin-crossover behaviour. Here, we reported the crystal stucture of complex [Fe(bpca)6](C1O4) CH3OH.(Fig. 1). The coordination environments of Fe(III) ions are completed by two bpca ligands with average Fe—N bond length of being 1.954 Å (Table 1). A classical hyrogen bond O—H···O exists between methanol and chlorate anion with D···A distance being 2.916 (3)Å (Table 2). The temperature-dependent magnetic susceptibility was measured down to 5 K. The data in the form of molar magnetic moment multiply temperature is nearly constant and equal to about 0.45 emu K mol-1, consistent with low spin state of Fe(III) (s = 1/2).

Experimental

A methanolic solution (25 ml) containing the bpca ligand (0.2 mmol, 0.046 g) was added dropwise to Fe(ClO4)2.6 H2O (0.1 mmol, 0.036 g). After stirring for 15 minutes, the dark solution was filtered. Red block-shaped crystals suitable for single-crystal X-ray diffraction were obtained by evaporating the resulting filtration in air for several days (yield: 56.2%). Anal calc (%). for C25 H20 Cl Fe N6 O9: H 3.15 C 46.95 N 13.15. Found: H 3.12, C 46.87, N 13.54.

Refinement

C-bound H atoms were placed geometrically and allowed to ride during refinement with C—H = 0.93–0.96 Å with Uiso(H) = 1.2 Ueq(C). The hydroxy H atom of the methanol solvent molecule was located in a difference Fourier map and refined as riding with the parent atom with Uiso(H) = 1.5Ueq(O).

Figures

Fig. 1.
The molecular structure of the title compound, the thermal ellipsoids were drawn at 50% probability level.

Crystal data

[Fe(C12H8N3O2)2]ClO4·CH4OZ = 2
Mr = 639.77F(000) = 654
Triclinic, P1Dx = 1.645 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71070 Å
a = 8.799 (3) ÅCell parameters from 5465 reflections
b = 11.603 (4) Åθ = 3.0–27.8°
c = 14.356 (6) ŵ = 0.76 mm1
α = 109.507 (4)°T = 143 K
β = 103.394 (3)°Block, red
γ = 100.091 (3)°0.32 × 0.26 × 0.23 mm
V = 1292.0 (8) Å3

Data collection

Bruker SMART APEX CCD area-detector diffractometer4421 independent reflections
Radiation source: fine-focus sealed tube4177 reflections with I > 2σ(I)
graphiteRint = 0.040
[var phi] and ω scansθmax = 25.0°, θmin = 3.2°
Absorption correction: multi-scan (SHELXTL; Sheldrick, 2008)h = −8→10
Tmin = 0.790, Tmax = 0.840k = −13→13
8499 measured reflectionsl = −17→16

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.107H-atom parameters constrained
S = 1.03w = 1/[σ2(Fo2) + (0.0537P)2 + 1.8601P] where P = (Fo2 + 2Fc2)/3
4421 reflections(Δ/σ)max < 0.001
379 parametersΔρmax = 1.48 e Å3
0 restraintsΔρmin = −0.48 e Å3

Special details

Experimental. The magnetic measurements were performed on Quantum Design SQUID, MPMS-5S magnetometer.
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
Fe10.58016 (4)0.81056 (3)0.23045 (2)0.01007 (12)
O10.2790 (2)0.51858 (16)−0.02782 (13)0.0148 (4)
N20.5013 (2)0.68770 (19)0.09138 (15)0.0112 (4)
O20.5569 (2)0.63892 (17)−0.06690 (13)0.0168 (4)
N10.3602 (2)0.73605 (19)0.23053 (15)0.0121 (4)
N60.6689 (2)0.70815 (19)0.30342 (16)0.0129 (4)
N30.7802 (2)0.84703 (19)0.19255 (16)0.0127 (4)
N50.6579 (2)0.93790 (19)0.36992 (15)0.0136 (4)
N40.5149 (2)0.95113 (19)0.19857 (15)0.0124 (4)
C50.2725 (3)0.6311 (2)0.14314 (18)0.0118 (5)
O40.7774 (3)0.97129 (19)0.54311 (14)0.0338 (5)
O30.6870 (3)1.15149 (18)0.46500 (15)0.0326 (5)
C70.5952 (3)0.6937 (2)0.02702 (18)0.0121 (5)
C60.3479 (3)0.6029 (2)0.05672 (18)0.0119 (5)
C90.8828 (3)0.7988 (2)0.0474 (2)0.0175 (5)
H9A0.86520.7542−0.02300.021*
C40.1249 (3)0.5577 (2)0.13335 (19)0.0165 (5)
H4A0.07050.48440.07390.020*
C150.4363 (3)1.1664 (3)0.1802 (2)0.0202 (6)
H15A0.40891.23790.17380.024*
C130.4368 (3)0.9487 (2)0.10510 (19)0.0141 (5)
H13A0.40960.87400.04640.017*
C80.7602 (3)0.7837 (2)0.09035 (19)0.0133 (5)
C111.0553 (3)0.9449 (3)0.2156 (2)0.0211 (6)
H11A1.15620.99950.25970.025*
C101.0327 (3)0.8812 (3)0.1110 (2)0.0226 (6)
H10A1.11740.89380.08380.027*
C240.6699 (3)0.5865 (2)0.2595 (2)0.0145 (5)
H24A0.62530.54340.18780.017*
C140.3960 (3)1.0545 (3)0.0939 (2)0.0178 (5)
H14A0.34171.05010.02850.021*
C220.8026 (4)0.5867 (3)0.4249 (2)0.0273 (6)
H22A0.84820.54580.46530.033*
C170.5555 (3)1.0616 (2)0.28249 (19)0.0160 (5)
C180.6414 (3)1.0583 (2)0.3844 (2)0.0182 (5)
C30.0577 (3)0.5945 (3)0.2137 (2)0.0189 (5)
H3A−0.04220.54630.20890.023*
C200.7334 (3)0.7695 (2)0.40816 (19)0.0177 (5)
C210.8008 (4)0.7121 (3)0.4710 (2)0.0257 (6)
H21A0.84410.75640.54270.031*
C10.2943 (3)0.7719 (2)0.30753 (19)0.0157 (5)
H1A0.35190.84430.36720.019*
C120.9269 (3)0.9267 (2)0.25399 (19)0.0156 (5)
H12A0.94230.97080.32420.019*
C230.7360 (3)0.5236 (3)0.3187 (2)0.0205 (6)
H23A0.73520.43930.28680.025*
C190.7269 (3)0.9048 (2)0.4504 (2)0.0188 (5)
C160.5182 (3)1.1700 (3)0.2764 (2)0.0208 (6)
H16A0.54761.24420.33580.025*
C20.1426 (3)0.7039 (3)0.3005 (2)0.0193 (6)
H2A0.09850.73200.35420.023*
Cl10.91561 (7)0.22764 (6)0.18640 (5)0.02052 (17)
O140.8085 (2)0.10315 (19)0.15308 (18)0.0319 (5)
O131.0750 (2)0.2169 (2)0.18132 (17)0.0346 (5)
O120.9291 (3)0.3020 (2)0.29168 (18)0.0458 (6)
O110.8522 (3)0.2870 (2)0.1189 (2)0.0512 (7)
C1W0.3474 (5)0.5122 (4)0.3889 (3)0.0481 (9)
H1WA0.25450.52550.41080.072*
H1WB0.34190.53130.32830.072*
H1WC0.44480.56680.44380.072*
O1W0.3486 (3)0.3837 (2)0.36481 (19)0.0415 (6)
H1W0.23700.32630.31210.050*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Fe10.01026 (19)0.0101 (2)0.0073 (2)0.00144 (14)0.00143 (14)0.00187 (15)
O10.0143 (8)0.0139 (9)0.0091 (9)0.0001 (7)0.0000 (7)0.0002 (8)
N20.0109 (10)0.0113 (10)0.0095 (10)0.0014 (8)0.0027 (8)0.0027 (8)
O20.0202 (9)0.0179 (9)0.0092 (9)0.0018 (7)0.0047 (7)0.0033 (7)
N10.0133 (10)0.0139 (10)0.0091 (10)0.0041 (8)0.0033 (8)0.0045 (9)
N60.0126 (10)0.0131 (10)0.0121 (10)0.0022 (8)0.0044 (8)0.0042 (9)
N30.0124 (10)0.0123 (10)0.0122 (10)0.0022 (8)0.0014 (8)0.0056 (8)
N50.0160 (10)0.0115 (10)0.0091 (10)0.0025 (8)0.0011 (8)0.0015 (8)
N40.0097 (9)0.0148 (10)0.0126 (10)0.0012 (8)0.0046 (8)0.0054 (9)
C50.0137 (11)0.0116 (11)0.0095 (11)0.0045 (9)0.0029 (9)0.0033 (10)
O40.0575 (15)0.0241 (11)0.0087 (10)0.0165 (10)−0.0048 (9)0.0003 (9)
O30.0580 (14)0.0145 (10)0.0134 (10)0.0100 (9)−0.0006 (9)−0.0009 (9)
C70.0141 (12)0.0115 (12)0.0127 (13)0.0056 (9)0.0053 (10)0.0053 (10)
C60.0125 (11)0.0122 (12)0.0113 (12)0.0041 (9)0.0020 (10)0.0057 (11)
C90.0177 (12)0.0204 (13)0.0164 (13)0.0053 (10)0.0068 (10)0.0086 (11)
C40.0143 (12)0.0179 (13)0.0117 (12)0.0012 (10)0.0010 (10)0.0028 (10)
C150.0205 (13)0.0209 (14)0.0277 (15)0.0101 (11)0.0104 (11)0.0157 (12)
C130.0098 (11)0.0188 (13)0.0123 (12)0.0019 (9)0.0026 (9)0.0058 (10)
C80.0140 (12)0.0139 (12)0.0132 (12)0.0049 (10)0.0035 (10)0.0067 (10)
C110.0116 (12)0.0226 (14)0.0256 (15)0.0007 (10)0.0006 (11)0.0108 (12)
C100.0143 (12)0.0304 (15)0.0271 (15)0.0053 (11)0.0080 (11)0.0156 (13)
C240.0145 (11)0.0134 (12)0.0163 (12)0.0045 (9)0.0079 (10)0.0043 (10)
C140.0136 (12)0.0257 (14)0.0194 (13)0.0061 (10)0.0066 (10)0.0140 (12)
C220.0356 (16)0.0287 (16)0.0272 (16)0.0166 (13)0.0088 (13)0.0192 (13)
C170.0147 (12)0.0156 (12)0.0147 (13)0.0010 (10)0.0031 (10)0.0048 (11)
C180.0219 (13)0.0141 (13)0.0150 (13)0.0038 (10)0.0032 (10)0.0036 (11)
C30.0127 (12)0.0250 (14)0.0169 (13)0.0005 (10)0.0048 (10)0.0079 (11)
C200.0204 (13)0.0175 (13)0.0132 (13)0.0045 (10)0.0032 (10)0.0054 (11)
C210.0362 (16)0.0251 (15)0.0149 (13)0.0113 (12)0.0030 (12)0.0087 (12)
C10.0178 (12)0.0176 (13)0.0112 (12)0.0057 (10)0.0048 (10)0.0045 (10)
C120.0152 (12)0.0156 (12)0.0131 (12)0.0023 (10)0.0002 (10)0.0060 (10)
C230.0229 (13)0.0172 (13)0.0268 (15)0.0077 (11)0.0144 (12)0.0098 (12)
C190.0218 (13)0.0180 (13)0.0120 (13)0.0058 (11)0.0004 (10)0.0036 (11)
C160.0260 (14)0.0148 (13)0.0210 (14)0.0067 (11)0.0078 (11)0.0055 (11)
C20.0194 (13)0.0269 (15)0.0153 (13)0.0084 (11)0.0093 (11)0.0091 (12)
Cl10.0209 (3)0.0169 (3)0.0216 (3)0.0046 (3)0.0049 (3)0.0063 (3)
O140.0243 (10)0.0215 (11)0.0485 (13)0.0023 (8)0.0087 (10)0.0160 (10)
O130.0217 (10)0.0423 (13)0.0359 (12)0.0036 (9)0.0139 (9)0.0097 (11)
O120.0401 (13)0.0555 (16)0.0267 (12)0.0222 (12)0.0075 (10)−0.0049 (11)
O110.0555 (16)0.0345 (13)0.0552 (16)0.0034 (12)−0.0092 (13)0.0299 (12)
C1W0.049 (2)0.049 (2)0.055 (2)0.0203 (18)0.0172 (18)0.0263 (19)
O1W0.0393 (13)0.0343 (13)0.0425 (14)0.0149 (10)0.0025 (11)0.0092 (11)

Geometric parameters (Å, °)

Fe1—N21.900 (2)C13—H13A0.9300
Fe1—N51.922 (2)C11—C101.381 (4)
Fe1—N61.974 (2)C11—C121.381 (4)
Fe1—N41.976 (2)C11—H11A0.9300
Fe1—N11.977 (2)C10—H10A0.9300
Fe1—N31.977 (2)C24—C231.388 (4)
O1—C61.206 (3)C24—H24A0.9300
N2—C71.384 (3)C14—H14A0.9300
N2—C61.391 (3)C22—C231.377 (4)
O2—C71.216 (3)C22—C211.387 (4)
N1—C11.344 (3)C22—H22A0.9300
N1—C51.362 (3)C17—C161.379 (4)
N6—C241.343 (3)C17—C181.500 (4)
N6—C201.356 (3)C3—C21.380 (4)
N3—C121.345 (3)C3—H3A0.9300
N3—C81.356 (3)C20—C211.379 (4)
N5—C191.379 (3)C20—C191.500 (4)
N5—C181.381 (3)C21—H21A0.9300
N4—C131.347 (3)C1—C21.390 (4)
N4—C171.353 (3)C1—H1A0.9300
C5—C41.371 (3)C12—H12A0.9300
C5—C61.507 (3)C23—H23A0.9300
O4—C191.219 (3)C16—H16A0.9300
O3—C181.211 (3)C2—H2A0.9300
C7—C81.499 (3)Cl1—O121.433 (2)
C9—C81.374 (4)Cl1—O141.434 (2)
C9—C101.380 (4)Cl1—O111.434 (2)
C9—H9A0.9300Cl1—O131.446 (2)
C4—C31.392 (4)C1W—O1W1.416 (4)
C4—H4A0.9300C1W—H1WA0.9600
C15—C141.381 (4)C1W—H1WB0.9600
C15—C161.384 (4)C1W—H1WC0.9600
C15—H15A0.9300O1W—H1W1.0342
C13—C141.385 (4)
N2—Fe1—N5178.55 (8)C12—C11—H11A120.3
N2—Fe1—N6100.02 (9)C9—C10—C11119.2 (2)
N5—Fe1—N681.43 (9)C9—C10—H10A120.4
N2—Fe1—N496.55 (9)C11—C10—H10A120.4
N5—Fe1—N482.01 (9)N6—C24—C23121.5 (2)
N6—Fe1—N4163.43 (9)N6—C24—H24A119.2
N2—Fe1—N182.14 (8)C23—C24—H24A119.2
N5—Fe1—N197.85 (9)C15—C14—C13119.8 (2)
N6—Fe1—N189.91 (8)C15—C14—H14A120.1
N4—Fe1—N192.51 (8)C13—C14—H14A120.1
N2—Fe1—N382.31 (8)C23—C22—C21119.2 (3)
N5—Fe1—N397.73 (9)C23—C22—H22A120.4
N6—Fe1—N391.22 (8)C21—C22—H22A120.4
N4—Fe1—N390.84 (8)N4—C17—C16122.9 (2)
N1—Fe1—N3164.37 (9)N4—C17—C18115.5 (2)
C7—N2—C6123.1 (2)C16—C17—C18121.6 (2)
C7—N2—Fe1117.82 (16)O3—C18—N5127.9 (2)
C6—N2—Fe1118.93 (16)O3—C18—C17122.0 (2)
C1—N1—C5118.1 (2)N5—C18—C17110.1 (2)
C1—N1—Fe1127.89 (17)C2—C3—C4118.6 (2)
C5—N1—Fe1113.91 (16)C2—C3—H3A120.7
C24—N6—C20118.5 (2)C4—C3—H3A120.7
C24—N6—Fe1126.44 (17)N6—C20—C21122.6 (2)
C20—N6—Fe1115.01 (17)N6—C20—C19114.9 (2)
C12—N3—C8118.2 (2)C21—C20—C19122.6 (2)
C12—N3—Fe1128.32 (17)C20—C21—C22118.5 (3)
C8—N3—Fe1113.43 (16)C20—C21—H21A120.7
C19—N5—C18123.3 (2)C22—C21—H21A120.7
C19—N5—Fe1118.66 (17)N1—C1—C2121.8 (2)
C18—N5—Fe1118.07 (16)N1—C1—H1A119.1
C13—N4—C17117.9 (2)C2—C1—H1A119.1
C13—N4—Fe1127.82 (17)N3—C12—C11121.8 (2)
C17—N4—Fe1114.28 (16)N3—C12—H12A119.1
N1—C5—C4122.6 (2)C11—C12—H12A119.1
N1—C5—C6115.1 (2)C22—C23—C24119.7 (3)
C4—C5—C6122.3 (2)C22—C23—H23A120.2
O2—C7—N2128.2 (2)C24—C23—H23A120.2
O2—C7—C8122.1 (2)O4—C19—N5127.6 (2)
N2—C7—C8109.7 (2)O4—C19—C20122.4 (2)
O1—C6—N2128.2 (2)N5—C19—C20110.0 (2)
O1—C6—C5122.5 (2)C17—C16—C15118.8 (2)
N2—C6—C5109.3 (2)C17—C16—H16A120.6
C8—C9—C10118.7 (2)C15—C16—H16A120.6
C8—C9—H9A120.6C3—C2—C1119.7 (2)
C10—C9—H9A120.6C3—C2—H2A120.2
C5—C4—C3119.1 (2)C1—C2—H2A120.2
C5—C4—H4A120.5O12—Cl1—O14109.89 (15)
C3—C4—H4A120.5O12—Cl1—O11110.31 (17)
C14—C15—C16118.6 (2)O14—Cl1—O11108.86 (14)
C14—C15—H15A120.7O12—Cl1—O13108.75 (13)
C16—C15—H15A120.7O14—Cl1—O13109.36 (13)
N4—C13—C14121.8 (2)O11—Cl1—O13109.66 (16)
N4—C13—H13A119.1O1W—C1W—H1WA109.5
C14—C13—H13A119.1O1W—C1W—H1WB109.5
N3—C8—C9122.6 (2)H1WA—C1W—H1WB109.5
N3—C8—C7115.4 (2)O1W—C1W—H1WC109.5
C9—C8—C7121.9 (2)H1WA—C1W—H1WC109.5
C10—C11—C12119.5 (2)H1WB—C1W—H1WC109.5
C10—C11—H11A120.3C1W—O1W—H1W108.2

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1W—H1W···O13i1.031.922.916 (3)160

Symmetry codes: (i) x−1, y, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2207).

References

  • Bruker (1997). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Wocadlo, S., Massa, W. & Folgado, J.-V. (1993). Inorg. Chim. Acta, 207, 199–206.

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