Di­aqua­bis­(2-ethyl-5-methyl­imidazole-4-sulfonato-κ2N3,O)nickel(II) dihydrate

Purdy, A.P.; Butcher, R.J.

doi:10.1107/S1600536813032169

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 70| Part 1| January 2014| Pages m18-m19

https://doi.org/10.1107/S1600536813032169

Open

access

Diaquabis(2-ethyl-5-methylimidazole-4-sulfonato-κ²N³,O)nickel(II) dihydrate

Andrew P. Purdy ^a ^* and Ray J. Butcher ^b

^aChemistry Division, Code 6100 Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA, and ^bDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA
^*Correspondence e-mail: andrew.purdy@nrl.navy.mil

(Received 13 October 2013; accepted 25 November 2013; online 14 December 2013)

In the title complex, [Ni(C₆H₉N₂O₃S)₂(H₂O)₂]·2H₂O, the Ni^II atom lies on an inversion center and is chelated by N and O atoms of two symmetry-equivalent imidazolesulfonate ligands in the basal plane, and two water O atoms in axial positions in an overall octahedral configuration. The crystal structure displays O—H⋯O and N—H⋯O hydrogen bonds, which connect the components into an extended three-dimensional network.

CCDC reference: 973660

Related literature

For examples of Ni–sulfonate complexes and MOFs, see: Lobana et al. (2004 ); Forbes & Sevov (2009 ); Kim et al. (2004 ); Yang et al. (2010 ). A small number of structurally characterized imidazole sulfonates are known, see: Kuhn et al. (2001 , 2002 ); Chidambaram et al. (1988 ). The 2-ethyl-4-methyl-5-sulfonate ligand is described by Purdy et al. (2007 ) and Purdy & Butcher (2011 ).

Experimental

Crystal data

[Ni(C₆H₉N₂O₃S)₂(H₂O)₂]·2H₂O
M_r = 509.20
Monoclinic, P 2₁ /a
a = 7.6037 (2) Å
b = 16.8934 (4) Å
c = 8.6574 (3) Å
β = 111.303 (3)°
V = 1036.08 (5) Å³
Z = 2
Cu Kα radiation
μ = 3.77 mm⁻¹
T = 123 K
0.52 × 0.46 × 0.35 mm

Data collection

Agilent Xcalibur Ruby Gemini diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012 ) T_min = 0.209, T_max = 1.000
2126 measured reflections
2126 independent reflections
2062 reflections with I > 2σ(I)

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.112
S = 1.18
2126 reflections
151 parameters
48 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.73 e Å⁻³
Δρ_min = −0.54 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W1⋯O2W	0.82 (2)	2.02 (2)	2.837 (3)	174 (4)
O1W—H1W2⋯O3ⁱ	0.81 (2)	1.96 (2)	2.739 (3)	161 (4)
O2W—H2W1⋯O2ⁱⁱ	0.80 (2)	1.97 (2)	2.751 (3)	167 (4)
O2W—H2W2⋯O2ⁱⁱⁱ	0.80 (2)	1.94 (2)	2.723 (3)	169 (4)
N2—H2A⋯O2W^iv	0.88	1.94	2.818 (3)	174
Symmetry codes: (i) -x, -y+1, -z+1; (ii) -x+1, -y+1, -z+1; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+1]$ ; (iv) -x+1, -y+1, -z+2.

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

CCDC reference: 973660

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: https://doi.org/10.1107/S1600536813032169/jj2177sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813032169/jj2177Isup2.hkl

checkCIF report

Comment top

The Ni atom lies on an inversion center and is chelated by N1 and O1 of the 2 symmetry equivalent imidazolesulfonate ligands in a plane, and 2 axial water molecules coordinated in an overall octahedral configuration. All of the Ni—O bond lengths (2.083 (2), 2.094 (2) Å) are about the same, and are in the normal range for octahedral coordinated Ni (2.05–2.12 Å). The largest deviation from the 90 ° angles of the octahedron is N1—Ni—O1, a result of the sulfonate group being attached to the imidazole ring. Two additional uncoordinated water molecules are present, but do not lie on any symmetry elements. There are no links other than hydrogen bonds between molecules, in contrast to the analogous unsolvated Cu(II) derivative (Purdy & Butcher, 2011). Hydrogen bonding links all the water molecules and N2, O2, and O3 into an extended structure in all three dimensions.

Related literature top

For examples of Ni–sulfonate complexes and MOFs, see: Lobana et al. (2004); Forbes & Sevov (2009); Kim et al. (2004); Yang et al. (2010). A small number of structurally characterized imidazole sulfonates are known, see: Kuhn et al. (2001, 2002); Chidambaram et al. (1988). The 2-ethyl-4-methyl-5-sulfonate ligand is described by Purdy et al. (2007) and Purdy & Butcher (2011).

Experimental top

A solution of the potassium salt of the 2-ethyl-4-methyl-imidazole-5-sulfonic acid was prepared by combining 1 g (5.25 mmol) of the free acid with 1.5 equivalents of KOH solution, and diluting the solution to 1M based on K⁺. (All solutions were made with distilled water.) Two test reactions were done in vials with 0.5 M solutions of Ni(BF₄)₂·6H₂O and MnSO₄·H₂O, a 0.2 ml metered pipet was used for the additions, and each vial contained one addition of all three solutions. After 1 month, one vial were heated to a boil and allowed to cool and the other remained at room temperature. After one year, large blue crystals of the title compound grew in the solution that was not heated.

Structure description top

For examples of Ni–sulfonate complexes and MOFs, see: Lobana et al. (2004); Forbes & Sevov (2009); Kim et al. (2004); Yang et al. (2010). A small number of structurally characterized imidazole sulfonates are known, see: Kuhn et al. (2001, 2002); Chidambaram et al. (1988). The 2-ethyl-4-methyl-5-sulfonate ligand is described by Purdy et al. (2007) and Purdy & Butcher (2011).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Diagram of C₁₂H₂₂N₄O₈S₂Ni, with uncoordinated water molecules not shown.
	Fig. 2. Packing diagram viewed down the c axis, displaying the hydrogen bonded interactions of both the coordinated and uncoordinated water molecules.

Diaquabis(2-ethyl-5-methylimidazole-4-sulfonato-κ²N³,O)nickel(II) dihydrate top

Crystal data top

[Ni(C₆H₉N₂O₃S)₂(H₂O)₂]·2H₂O	F(000) = 532
M_r = 509.20	D_x = 1.632 Mg m⁻³
Monoclinic, P2₁/a	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2yab	Cell parameters from 4614 reflections
a = 7.6037 (2) Å	θ = 5.2–75.5°
b = 16.8934 (4) Å	µ = 3.77 mm⁻¹
c = 8.6574 (3) Å	T = 123 K
β = 111.303 (3)°	Block, blue
V = 1036.08 (5) Å³	0.52 × 0.46 × 0.35 mm
Z = 2

Data collection top

Agilent Xcalibur Ruby Gemini diffractometer	2126 independent reflections
Radiation source: Enhance (Cu) X-ray Source	2062 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.000
Detector resolution: 10.5081 pixels mm^-1	θ_max = 75.8°, θ_min = 5.2°
ω scans	h = −9→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = 0→21
T_min = 0.209, T_max = 1.000	l = 0→10
2126 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.112	H atoms treated by a mixture of independent and constrained refinement
S = 1.18	w = 1/[σ²(F_o²) + (0.0411P)² + 2.2827P] where P = (F_o² + 2F_c²)/3
2126 reflections	(Δ/σ)_max < 0.001
151 parameters	Δρ_max = 0.73 e Å⁻³
48 restraints	Δρ_min = −0.54 e Å⁻³

Crystal data top

[Ni(C₆H₉N₂O₃S)₂(H₂O)₂]·2H₂O	V = 1036.08 (5) Å³
M_r = 509.20	Z = 2
Monoclinic, P2₁/a	Cu Kα radiation
a = 7.6037 (2) Å	µ = 3.77 mm⁻¹
b = 16.8934 (4) Å	T = 123 K
c = 8.6574 (3) Å	0.52 × 0.46 × 0.35 mm
β = 111.303 (3)°

Data collection top

Agilent Xcalibur Ruby Gemini diffractometer	2126 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	2062 reflections with I > 2σ(I)
T_min = 0.209, T_max = 1.000	R_int = 0.000
2126 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	48 restraints
wR(F²) = 0.112	H atoms treated by a mixture of independent and constrained refinement
S = 1.18	Δρ_max = 0.73 e Å⁻³
2126 reflections	Δρ_min = −0.54 e Å⁻³
151 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
Ni	0.5000	0.5000	0.5000	0.00455 (19)
S1	0.13784 (8)	0.60394 (4)	0.38692 (7)	0.00676 (18)
O1	0.2439 (3)	0.54424 (11)	0.3337 (2)	0.0082 (4)
O2	0.1485 (3)	0.68145 (12)	0.3149 (2)	0.0148 (4)
O3	−0.0536 (3)	0.58051 (13)	0.3598 (2)	0.0165 (4)
O1W	0.3581 (3)	0.40250 (11)	0.5452 (2)	0.0104 (4)
H1W1	0.422 (5)	0.378 (2)	0.629 (4)	0.027 (11)*
H1W2	0.267 (4)	0.417 (2)	0.563 (5)	0.027 (11)*
O2W	0.5754 (3)	0.30842 (12)	0.8196 (2)	0.0129 (4)
H2W1	0.667 (4)	0.309 (2)	0.795 (5)	0.014 (9)*
H2W2	0.519 (5)	0.2680 (16)	0.790 (5)	0.019 (10)*
N1	0.4281 (3)	0.56704 (13)	0.6667 (3)	0.0065 (4)
N2	0.3814 (3)	0.63709 (13)	0.8610 (3)	0.0094 (5)
H2A	0.3996	0.6567	0.9598	0.011*
C1	0.2651 (4)	0.61089 (15)	0.5997 (3)	0.0072 (5)
C2	0.2329 (4)	0.65519 (15)	0.7178 (3)	0.0085 (5)
C3	0.0834 (4)	0.71410 (17)	0.7081 (4)	0.0155 (6)
H3A	−0.0366	0.6972	0.6241	0.023*
H3B	0.1188	0.7659	0.6777	0.023*
H3C	0.0696	0.7179	0.8161	0.023*
C4	0.4953 (4)	0.58422 (15)	0.8257 (3)	0.0083 (5)
C5	0.6769 (4)	0.55417 (16)	0.9505 (3)	0.0110 (5)
H5A	0.6884	0.4968	0.9328	0.013*
H5B	0.6752	0.5615	1.0634	0.013*
C6	0.8474 (4)	0.59737 (17)	0.9371 (4)	0.0152 (6)
H6A	0.9637	0.5738	1.0147	0.023*
H6B	0.8420	0.6534	0.9641	0.023*
H6C	0.8457	0.5925	0.8237	0.023*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni	0.0030 (3)	0.0058 (3)	0.0026 (3)	0.0012 (2)	−0.0017 (2)	−0.0004 (2)
S1	0.0039 (3)	0.0098 (3)	0.0042 (3)	0.0027 (2)	−0.0014 (2)	0.0007 (2)
O1	0.0067 (7)	0.0098 (7)	0.0051 (7)	0.0030 (6)	−0.0012 (5)	−0.0014 (6)
O2	0.0208 (11)	0.0099 (9)	0.0122 (9)	0.0059 (8)	0.0043 (8)	0.0056 (7)
O3	0.0112 (8)	0.0241 (8)	0.0131 (7)	−0.0003 (6)	0.0031 (6)	−0.0012 (6)
O1W	0.0087 (9)	0.0105 (9)	0.0108 (9)	0.0002 (7)	0.0023 (7)	0.0014 (7)
O2W	0.0164 (10)	0.0113 (9)	0.0105 (9)	−0.0051 (8)	0.0042 (8)	−0.0044 (7)
N1	0.0054 (8)	0.0070 (8)	0.0056 (7)	0.0000 (6)	0.0002 (6)	0.0002 (6)
N2	0.0121 (11)	0.0102 (11)	0.0050 (10)	−0.0014 (8)	0.0020 (8)	−0.0025 (8)
C1	0.0065 (8)	0.0075 (8)	0.0065 (8)	−0.0002 (7)	0.0008 (7)	−0.0005 (7)
C2	0.0078 (12)	0.0081 (11)	0.0085 (12)	−0.0012 (9)	0.0015 (10)	−0.0021 (9)
C3	0.0132 (14)	0.0129 (13)	0.0197 (14)	0.0028 (11)	0.0052 (11)	−0.0049 (11)
C4	0.0110 (13)	0.0059 (11)	0.0077 (12)	−0.0021 (9)	0.0029 (10)	−0.0003 (9)
C5	0.0115 (9)	0.0116 (9)	0.0081 (8)	0.0007 (7)	0.0013 (7)	0.0007 (7)
C6	0.0104 (13)	0.0177 (14)	0.0122 (13)	−0.0012 (10)	−0.0023 (10)	−0.0014 (10)

Geometric parameters (Å, º) top

Ni—N1	2.058 (2)	N2—C4	1.354 (4)
Ni—N1ⁱ	2.058 (2)	N2—C2	1.374 (3)
Ni—O1W	2.0825 (19)	N2—H2A	0.8800
Ni—O1Wⁱ	2.0825 (19)	C1—C2	1.359 (4)
Ni—O1	2.0941 (18)	C2—C3	1.490 (4)
Ni—O1ⁱ	2.0941 (18)	C3—H3A	0.9800
S1—O3	1.443 (2)	C3—H3B	0.9800
S1—O2	1.465 (2)	C3—H3C	0.9800
S1—O1	1.4662 (18)	C4—C5	1.499 (4)
S1—C1	1.746 (3)	C5—C6	1.528 (4)
O1W—H1W1	0.823 (19)	C5—H5A	0.9900
O1W—H1W2	0.808 (19)	C5—H5B	0.9900
O2W—H2W1	0.798 (18)	C6—H6A	0.9800
O2W—H2W2	0.796 (18)	C6—H6B	0.9800
N1—C4	1.315 (3)	C6—H6C	0.9800
N1—C1	1.378 (3)

N1—Ni—N1ⁱ	180.0	C4—N2—H2A	125.5
N1—Ni—O1W	90.90 (8)	C2—N2—H2A	125.5
N1ⁱ—Ni—O1W	89.10 (8)	C2—C1—N1	111.1 (2)
N1—Ni—O1Wⁱ	89.10 (8)	C2—C1—S1	130.4 (2)
N1ⁱ—Ni—O1Wⁱ	90.90 (8)	N1—C1—S1	118.48 (19)
O1W—Ni—O1Wⁱ	180.00 (6)	C1—C2—N2	104.1 (2)
N1—Ni—O1	82.42 (8)	C1—C2—C3	131.9 (2)
N1ⁱ—Ni—O1	97.58 (8)	N2—C2—C3	124.0 (2)
O1W—Ni—O1	89.75 (8)	C2—C3—H3A	109.5
O1Wⁱ—Ni—O1	90.25 (8)	C2—C3—H3B	109.5
N1—Ni—O1ⁱ	97.58 (8)	H3A—C3—H3B	109.5
N1ⁱ—Ni—O1ⁱ	82.42 (8)	C2—C3—H3C	109.5
O1W—Ni—O1ⁱ	90.25 (8)	H3A—C3—H3C	109.5
O1Wⁱ—Ni—O1ⁱ	89.75 (8)	H3B—C3—H3C	109.5
O1—Ni—O1ⁱ	180.00 (14)	N1—C4—N2	110.2 (2)
O3—S1—O2	112.61 (13)	N1—C4—C5	125.8 (2)
O3—S1—O1	113.45 (12)	N2—C4—C5	123.9 (2)
O2—S1—O1	111.06 (11)	C4—C5—C6	111.6 (2)
O3—S1—C1	109.24 (12)	C4—C5—H5A	109.3
O2—S1—C1	107.09 (12)	C6—C5—H5A	109.3
O1—S1—C1	102.73 (11)	C4—C5—H5B	109.3
S1—O1—Ni	120.66 (10)	C6—C5—H5B	109.3
Ni—O1W—H1W1	112 (3)	H5A—C5—H5B	108.0
Ni—O1W—H1W2	109 (3)	C5—C6—H6A	109.5
H1W1—O1W—H1W2	105 (3)	C5—C6—H6B	109.5
H2W1—O2W—H2W2	110 (3)	H6A—C6—H6B	109.5
C4—N1—C1	105.7 (2)	C5—C6—H6C	109.5
C4—N1—Ni	138.96 (19)	H6A—C6—H6C	109.5
C1—N1—Ni	115.34 (16)	H6B—C6—H6C	109.5
C4—N2—C2	109.0 (2)

O3—S1—O1—Ni	−124.06 (13)	Ni—N1—C1—S1	1.0 (3)
O2—S1—O1—Ni	107.92 (14)	O3—S1—C1—C2	−57.4 (3)
C1—S1—O1—Ni	−6.27 (15)	O2—S1—C1—C2	64.8 (3)
N1—Ni—O1—S1	6.10 (13)	O1—S1—C1—C2	−178.1 (3)
N1ⁱ—Ni—O1—S1	−173.90 (13)	O3—S1—C1—N1	124.0 (2)
O1W—Ni—O1—S1	97.04 (13)	O2—S1—C1—N1	−113.8 (2)
O1Wⁱ—Ni—O1—S1	−82.96 (13)	O1—S1—C1—N1	3.2 (2)
O1ⁱ—Ni—O1—S1	89 (6)	N1—C1—C2—N2	−0.2 (3)
N1ⁱ—Ni—N1—C4	81 (8)	S1—C1—C2—N2	−178.9 (2)
O1W—Ni—N1—C4	89.7 (3)	N1—C1—C2—C3	177.0 (3)
O1Wⁱ—Ni—N1—C4	−90.3 (3)	S1—C1—C2—C3	−1.7 (5)
O1—Ni—N1—C4	179.4 (3)	C4—N2—C2—C1	0.2 (3)
O1ⁱ—Ni—N1—C4	−0.6 (3)	C4—N2—C2—C3	−177.3 (3)
N1ⁱ—Ni—N1—C1	−102 (8)	C1—N1—C4—N2	−0.1 (3)
O1W—Ni—N1—C1	−93.13 (18)	Ni—N1—C4—N2	177.21 (19)
O1Wⁱ—Ni—N1—C1	86.87 (18)	C1—N1—C4—C5	−176.8 (2)
O1—Ni—N1—C1	−3.50 (17)	Ni—N1—C4—C5	0.5 (4)
O1ⁱ—Ni—N1—C1	176.50 (17)	C2—N2—C4—N1	0.0 (3)
C4—N1—C1—C2	0.2 (3)	C2—N2—C4—C5	176.7 (2)
Ni—N1—C1—C2	−177.83 (17)	N1—C4—C5—C6	76.8 (3)
C4—N1—C1—S1	179.10 (18)	N2—C4—C5—C6	−99.4 (3)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O2W	0.82 (2)	2.02 (2)	2.837 (3)	174 (4)
O1W—H1W2···O3ⁱⁱ	0.81 (2)	1.96 (2)	2.739 (3)	161 (4)
O2W—H2W1···O2ⁱ	0.80 (2)	1.97 (2)	2.751 (3)	167 (4)
O2W—H2W1···S1ⁱ	0.80 (2)	2.92 (3)	3.602 (2)	145 (3)
O2W—H2W2···O2ⁱⁱⁱ	0.80 (2)	1.94 (2)	2.723 (3)	169 (4)
N2—H2A···O2W^iv	0.88	1.94	2.818 (3)	174

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O2W	0.823 (19)	2.017 (19)	2.837 (3)	174 (4)
O1W—H1W2···O3ⁱ	0.808 (19)	1.96 (2)	2.739 (3)	161 (4)
O2W—H2W1···O2ⁱⁱ	0.798 (18)	1.97 (2)	2.751 (3)	167 (4)
O2W—H2W1···S1ⁱⁱ	0.798 (18)	2.92 (3)	3.602 (2)	145 (3)
O2W—H2W2···O2ⁱⁱⁱ	0.796 (18)	1.94 (2)	2.723 (3)	169 (4)
N2—H2A···O2W^iv	0.88	1.94	2.818 (3)	174.4

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

Acknowledgements

We thank The Office of Naval Research for financial support. RJB wishes to acknowledge the NSF–MRI program (grant CHE-0619278) for funds to purchase the diffractometer.

References

Agilent (2012). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England. Google Scholar
Chidambaram, Sp., Aravamudan, G. & Seshasayee, M. (1988). Acta Cryst. C44, 898–900. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Forbes, T. Z. & Sevov, S. C. (2009). Inorg. Chem. 48, 6873–6878. Web of Science CSD CrossRef PubMed CAS Google Scholar
Kim, D. S., Forster, P. M., Le Toquin, R. & Cheetham, A. K. (2004). Chem. Commun. pp. 2148–2149. Web of Science CSD CrossRef Google Scholar
Kuhn, N., Eichele, K. & Walker, M. (2001). Z. Anorg. Allg. Chem. 627, 2565–2567. CrossRef CAS Google Scholar
Kuhn, N., Eichele, K., Walker, M., Berends, T. & Minkwitz, R. (2002). Z. Anorg. Allg. Chem. 628, 2026–2032. CrossRef CAS Google Scholar
Lobana, T. S., Kinoshita, I., Kimura, K., Nishioka, T., Shiomi, D. & Isobe, K. (2004). Eur. J. Inorg. Chem. pp. 356–367. Web of Science CSD CrossRef Google Scholar
Purdy, A. P. & Butcher, R. J. (2011). Acta Cryst. E67, m1303–m1304. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Purdy, A. P., Gilardi, R., Luther, J. & Butcher, R. J. (2007). Polyhedron, 26, 3930–3938. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yang, F., Wu, Z.-H. & Cai, J.-H. (2010). Acta Cryst. E66, m748. Web of Science CSD CrossRef IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.