Crystal structure of bis­(pivaloyl­hydroxamato-κ2O,O′)copper(II)

Goleva, K.; Naumova, D.; Pavlishchuk, A.; Addison, A.W.; Zeller, M.

doi:10.1107/S2056989018012227

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 74| Part 9| September 2018| Pages 1384-1387

https://doi.org/10.1107/S2056989018012227

Open

access

Crystal structure of bis(pivaloylhydroxamato-κ²O,O′)copper(II)

Kateryna Goleva,^a Dina Naumova,^a Anna Pavlishchuk,^a ^* Anthony W. Addison ^b and Matthias Zeller ^c

^aDepartment of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska str. 62, Kiev, 01601, Ukraine, ^bDepartment of Chemistry, Drexel University, Philadelphia, PA 19104-2816, USA, and ^cDepartment of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN 47907-2084, USA
^*Correspondence e-mail: annpavlis@ukr.net

Edited by J. Ellena, Universidade de Sâo Paulo, Brazil (Received 8 August 2018; accepted 28 August 2018; online 31 August 2018)

Reaction of copper(II) nitrate with pivaloylhydroxamic acid yielded the title compound, [Cu(pivHA)₂] (where pivHA⁻ is pivaloyl hydroxamate, C₅H₁₀NO₂). The centrosymmetric mononuclear complex consists of a Cu^II ion, which is located on a center of inversion, with two coordinated pivaloyl hydroxamate monoanions. The Cu^II ion has a square-planar coordination environment consisting of four O atoms – two carbonyl O atoms and two hydroxamate O atoms from two hydroxamate pivHA⁻ ligands. The pivHA⁻ anions are coordinated to copper(II) in a trans-mode, forming two five-membered O,O′-chelate rings.

Keywords: crystal structure; copper(II); hydroxamates; pivalate derivatives; mononuclear complexes.

CCDC reference: 1864482

1. Chemical context

Numerous studies over the past decade of various hydroxamate complexes with 3d and 4f metal ions have been inspired by their potential applications in molecular magnetism, luminescence, adsorption and catalysis (Ostrowska et al., 2016 ; Pavlishchuk et al., 2015 ). The ability of further functionalized hydroxamic acids to serve as bridging ligands and to form polynuclear species with different structural motifs has been comprehensively examined in recent years (Mezei et al., 2007 ; Pavlishchuk et al., 2018 ; Odarich et al., 2016 ; McDonald et al., 2014 , 2015 ; Gaynor et al., 2002 ). Studies of simple unsubstituted hydroxamic acids have been undertaken because of their possible application as mimics of mononuclear iron(III) siderophores (Marmion et al., 2004 ). As a result of the potentially multiple coordination modes of unsubstituted hydroxamic acids, they can also lead to the formation of polynuclear assemblies (Tirfoin et al., 2014 ). However, reactions of unsubstituted hydroxamic acids with transition metal ions lead mainly to the formation of octahedral 1:3 (Abu-Dari et al., 1979 ) or square-planar 1:2 (Baughman et al., 2000 ) complexes with the hydroxamate in an O,O′-coordination mode. The ability of pivalic acid itself to form polynuclear metallamacrocyclic complexes with various metal ions is well known (Vitórica-Yrezábal et al., 2017 ; Garlatti et al., 2018 ). The aim of the current work was to investigate if a tert-butyl-substituted hydroxamic acid (i.e. the hydroxamate analogue of pivalic acid) could be used as a scaffold for the preparation of polynuclear copper(II) complexes.

2. Structural commentary

Crystals of the title compound 1 were obtained by reaction of copper(II) nitrate hexahydrate with pivaloylhydroxamic acid in methanol.

Complex 1 crystallizes in the space group I4₁/a, with eight [Cu(pivHA)₂] complex molecules per unit cell. The [Cu(pivHA)₂] molecules are centrosymmetric, with the copper ion located on an inversion center. Each [Cu(pivHA)₂] molecule contains one copper(II) ion in a square-planar coordination environment generated by the coordination of two pivaloylhydroxamate monoanions, forming five-membered chelate rings through both the carbonyl and hydroxamate O atoms (Fig. 1). The centrosymmetric nature of the complex forces the copper(II) ions to be exactly coplanar with the four donor O atoms, O1O2O1ⁱO2ⁱ [symmetry code: (i) −x, 1 − y, −z], and the two pivHA⁻ monoanions in [Cu(pivHA)₂] are necessarily mutually trans-coordinated. The axial positions of the copper(II) ions remain unoccupied. The Cu—O_carbonyl and Cu—O_hydroxamate bond lengths are typical for copper(II) hydroxamate or oximate complexes (Buvailo et al., 2012 ; Pavlishchuk et al., 2017a ,b ) (Table 1). The hydroxamate N—H groups remain protonated and are not involved in metal coordination. Deprotonation of the N—H groups could possibly be achieved at higher pH without hydrolysis of hydroxamic acid, which might aid in the formation of polynuclear complexes.

Table 1
Selected geometric parameters (Å, °)

C1—O2	1.2821 (13)	O1—Cu1	1.8899 (8)
C1—N1	1.3066 (14)	O2—Cu1	1.9244 (8)
N1—O1	1.3764 (12)

O1—Cu1—O1ⁱ	180 (5)	O1—Cu1—O2ⁱ	95.16 (3)
O1—Cu1—O2	84.84 (3)	O1ⁱ—Cu1—O2ⁱ	84.84 (3)
O1ⁱ—Cu1—O2	95.16 (3)	O2—Cu1—O2ⁱ	180
Symmetry code: (i) -x, -y+1, -z.

Figure 1
The molecular structure of complex 1 showing the neutral centrosymmetric fragment [Cu(pivHA)₂], along with the atom labelling. Displacement ellipsoids are at the 50% probability level. Symmetry code: (') −x, 1 − y, −z.

3. Supramolecular features

Adjacent [Cu(pivHA)₂] complexes are connected to each other via N1–H1⋯O1ⁱⁱ hydrogen bonds between the hydroxamate N—H group of one complex molecule and a deprotonated hydroxamate oxygen of an adjacent [Cu(pivHA)₂] molecule (Table 2, Fig. 2). Four of these N—H⋯O hydrogen bonds connect molecules into tetramers arranged around a fourfold rotoinversion center. The N—H group of the second hydroxamate ligand of each complex creates an equivalent tetramer trans across the copper ion, thus creating an infinite three-dimensional network of corner-connected tetramers (with the copper ions acting as the bridging element, Fig. 3).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱⁱ	0.88	1.90	2.7185 (13)	154
Symmetry code: (ii) $[y-{\script{1\over 4}}, -x+{\script{1\over 4}}, -z+{\script{1\over 4}}]$ .

Figure 2
A fragment of the lattice of complex 1, showing the intramolecular hydrogen-bonding connections (dashed lines) between the [Cu(pivHA)₂] molecules. The tert-butyl groups are omitted for clarity.

Figure 3
A fragment of the packing of complex 1, showing the formation of supramolecular tetramers [Cu(pivHA)₂]₄ formed by hydrogen bonds. The tert-butyl groups are omitted for clarity.

4. Database survey

The Cambridge Structural Database (CSD, Version 5.27, updated in August 2012; Groom et al., 2016 ) contains one report with structural information for pivaloylhydroxamic acid (CCDC 1155138; Due et al., 1987 ). Though the survey did not contain any information about complexes with pivaloylhydroxamic acid, there are two reports devoted to structural studies of Th⁴⁺ (1180613 and 1180614; Smith & Raymond, 1981 ) and MoO₂²⁺ (763210–763214; Dzyuba et al., 2010 ) complexes with structurally similar ligands (N-isopropyl-2,2-dimethylpropanehydroxamate, N-isopropyl-3,3-dimethylbutanehydroxamate and decano-, N-methyl-decano-, N-methyl-hexano-, N-methyl-1-adamantano- or N-tert-butyl-hexanohydroxamates, respectively). It should be mentioned that coordination of hydroxamate ligands in the O,O′-chelating mode is quite typical (Tedeschi et al., 2003 ; Seitz et al., 2007a ,b ; Brewer & Sinn, 1981 ) and the CSD contains many records with such binding in various mononuclear bis-hydroxamate complexes (e.g. Drovetskaia et al., 1996 ; Li et al., 2004 ; Fisher et al., 1989 ; Harrison et al., 1976 ), which are usually coordinated in the trans- mode with respect to each other (Gaynor et al., 2001 ; Lasri et al., 2012 ; Casellato et al., 1984 ).

5. Synthesis and crystallization

A solution of pivaloylhydroxamic acid (23.4 mg, 0.20 mmol) in 5 mL of methanol was added to copper(II) nitrate hexahydrate (29.6 mg, 0.10 mmol) in 5 mL of methanol. The resulting blue solution was stirred for 30 min. at room temperature, filtered and left for slow evaporation. After a week, blue crystals suitable for single crystal X-ray analysis had formed. Yield: 23 mg (78%). Elemental analysis C:H:N Expected (calculated): 40.75 (40.60): 7.03 (6.81): 9.22 (9.47). IR in KBr pellets (cm⁻¹): 3400 (ν_N–H); 3196–3040 (ν_O–H, likely due to the presence of N1—H1⋯O1ⁱⁱ hydrogen bonds); 1595 and 1503 (ν_{amid I}); 1330, 1220 and 1053 (ν_C–C and ν_-C-N); 963 (ν_N–O).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms attached to carbon and nitrogen atoms were positioned geometrically and constrained to ride on their parent atoms: C—H =0.98 Å with U_iso(H) = 1.5U_eq(C) and N—H = 0.88 Å with U_iso(H) = 1.2U_eq(N). Methyl H atoms were allowed to rotate but not to tip to best fit the experimental electron density.

Table 3
Experimental details

Crystal data
Chemical formula	[Cu(C₅H₁₀NO₂)₂]
M_r	295.82
Crystal system, space group	Tetragonal, I4₁/a
Temperature (K)	100
a, c (Å)	12.8059 (5), 17.7051 (8)
V (Å³)	2903.5 (3)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	1.51
Crystal size (mm)	0.35 × 0.35 × 0.29

Data collection
Diffractometer	Bruker D8 Quest CMOS
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.656, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections	24433, 2764, 2444
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.769

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.074, 1.19
No. of reflections	2764
No. of parameters	82
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.46, −0.48
Computer programs: APEX2 and, SAINT (Bruker, 2014 ), SHELXS97 (Sheldrick, 2008 ), SHELXL2018 (Sheldrick, 2015 ), shelXle (Hübschle et al., 2011 ), Mercury (Macrae et al., 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1864482

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989018012227/ex2012sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018012227/ex2012Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989018012227/ex2012Isup3.cdx

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015), shelXle (Hübschle et al., 2011); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Bis(pivaloylhydroxamato-κ²O,O')copper(II) top

Crystal data top

[Cu(C₅H₁₀NO₂)₂]	D_x = 1.353 Mg m⁻³
M_r = 295.82	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4₁/a	Cell parameters from 9939 reflections
a = 12.8059 (5) Å	θ = 3.2–33.2°
c = 17.7051 (8) Å	µ = 1.51 mm⁻¹
V = 2903.5 (3) Å³	T = 100 K
Z = 8	Prism, blue
F(000) = 1240	0.35 × 0.35 × 0.29 mm

Data collection top

Bruker AXS D8 Quest CMOS diffractometer	2764 independent reflections
Radiation source: I-mu-S microsource X-ray tube	2444 reflections with I > 2σ(I)
Laterally graded multilayer (Goebel) mirror monochromator	R_int = 0.035
ω and phi scans	θ_max = 33.2°, θ_min = 3.2°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −19→19
T_min = 0.656, T_max = 0.747	k = −19→19
24433 measured reflections	l = −27→27

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.074	H-atom parameters constrained
S = 1.19	w = 1/[σ²(F_o²) + (0.0257P)² + 3.2993P] where P = (F_o² + 2F_c²)/3
2764 reflections	(Δ/σ)_max < 0.001
82 parameters	Δρ_max = 0.46 e Å⁻³
0 restraints	Δρ_min = −0.48 e Å⁻³

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.13160 (8)	0.34258 (8)	−0.02113 (6)	0.01465 (18)
C2	0.20901 (9)	0.26772 (9)	−0.05643 (7)	0.01747 (19)
C3	0.30109 (12)	0.33273 (12)	−0.08492 (10)	0.0327 (3)
H3A	0.349813	0.287558	−0.112390	0.049*
H3B	0.337056	0.364691	−0.041874	0.049*
H3C	0.275434	0.387597	−0.118744	0.049*
C4	0.15406 (12)	0.21475 (12)	−0.12341 (8)	0.0284 (3)
H4A	0.130218	0.268097	−0.159159	0.043*
H4B	0.093923	0.174854	−0.105007	0.043*
H4C	0.203005	0.167530	−0.148793	0.043*
C5	0.24745 (12)	0.18527 (12)	−0.00063 (8)	0.0274 (3)
H5A	0.187982	0.144200	0.017576	0.041*
H5B	0.281569	0.219691	0.042206	0.041*
H5C	0.297448	0.139024	−0.025866	0.041*
N1	0.10376 (7)	0.33335 (8)	0.04955 (5)	0.01550 (17)
H1	0.128862	0.282995	0.078083	0.019*
O1	0.03387 (7)	0.40497 (7)	0.07791 (5)	0.01837 (16)
O2	0.09269 (7)	0.41676 (7)	−0.06079 (5)	0.01830 (16)
Cu1	0.000000	0.500000	0.000000	0.01360 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0150 (4)	0.0146 (4)	0.0143 (4)	−0.0005 (3)	0.0017 (3)	0.0009 (3)
C2	0.0180 (5)	0.0179 (5)	0.0166 (5)	0.0020 (4)	0.0038 (4)	0.0011 (4)
C3	0.0242 (6)	0.0314 (7)	0.0424 (8)	−0.0013 (5)	0.0165 (6)	0.0028 (6)
C4	0.0311 (7)	0.0303 (6)	0.0238 (6)	0.0075 (5)	−0.0015 (5)	−0.0098 (5)
C5	0.0321 (7)	0.0275 (6)	0.0227 (6)	0.0144 (5)	0.0056 (5)	0.0046 (5)
N1	0.0168 (4)	0.0156 (4)	0.0142 (4)	0.0034 (3)	0.0031 (3)	0.0026 (3)
O1	0.0227 (4)	0.0186 (4)	0.0138 (3)	0.0077 (3)	0.0063 (3)	0.0033 (3)
O2	0.0241 (4)	0.0172 (4)	0.0136 (3)	0.0045 (3)	0.0037 (3)	0.0035 (3)
Cu1	0.01670 (10)	0.01244 (9)	0.01165 (9)	0.00085 (6)	0.00182 (6)	0.00171 (6)

Geometric parameters (Å, º) top

C1—O2	1.2821 (13)	C4—H4B	0.9800
C1—N1	1.3066 (14)	C4—H4C	0.9800
C1—C2	1.5141 (16)	C5—H5A	0.9800
C2—C5	1.5275 (18)	C5—H5B	0.9800
C2—C3	1.5290 (18)	C5—H5C	0.9800
C2—C4	1.5368 (18)	N1—O1	1.3764 (12)
C3—H3A	0.9800	N1—H1	0.8800
C3—H3B	0.9800	O1—Cu1	1.8899 (8)
C3—H3C	0.9800	O2—Cu1	1.9244 (8)
C4—H4A	0.9800

O2—C1—N1	119.04 (10)	H4A—C4—H4C	109.5
O2—C1—C2	119.84 (10)	H4B—C4—H4C	109.5
N1—C1—C2	121.12 (10)	C2—C5—H5A	109.5
C1—C2—C5	112.43 (10)	C2—C5—H5B	109.5
C1—C2—C3	107.24 (10)	H5A—C5—H5B	109.5
C5—C2—C3	109.95 (12)	C2—C5—H5C	109.5
C1—C2—C4	107.35 (10)	H5A—C5—H5C	109.5
C5—C2—C4	109.97 (11)	H5B—C5—H5C	109.5
C3—C2—C4	109.81 (11)	C1—N1—O1	117.82 (9)
C2—C3—H3A	109.5	C1—N1—H1	121.1
C2—C3—H3B	109.5	O1—N1—H1	121.1
H3A—C3—H3B	109.5	N1—O1—Cu1	108.18 (6)
C2—C3—H3C	109.5	C1—O2—Cu1	110.11 (7)
H3A—C3—H3C	109.5	O1—Cu1—O1ⁱ	180.00 (5)
H3B—C3—H3C	109.5	O1—Cu1—O2	84.84 (3)
C2—C4—H4A	109.5	O1ⁱ—Cu1—O2	95.16 (3)
C2—C4—H4B	109.5	O1—Cu1—O2ⁱ	95.16 (3)
H4A—C4—H4B	109.5	O1ⁱ—Cu1—O2ⁱ	84.84 (3)
C2—C4—H4C	109.5	O2—Cu1—O2ⁱ	180.0

O2—C1—C2—C5	179.56 (11)	C2—C1—N1—O1	179.33 (10)
N1—C1—C2—C5	−0.14 (16)	C1—N1—O1—Cu1	−0.49 (12)
O2—C1—C2—C3	58.59 (15)	N1—C1—O2—Cu1	1.02 (13)
N1—C1—C2—C3	−121.11 (13)	C2—C1—O2—Cu1	−178.69 (8)
O2—C1—C2—C4	−59.37 (14)	N1—O1—Cu1—O2	0.79 (7)
N1—C1—C2—C4	120.94 (12)	N1—O1—Cu1—O2ⁱ	−179.21 (7)
O2—C1—N1—O1	−0.37 (16)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱⁱ	0.88	1.90	2.7185 (13)	154

Symmetry code: (ii) y−1/4, −x+1/4, −z+1/4.

Acknowledgements

AWA thanks Drexel University for support.

Funding information

Funding for this research was provided by: National Science Foundation, Division of Materials Research (grant No. 1337296 to Matthias Zeller).

References

Abu-Dari, K., Ekstrand, J. D., Freyberg, D. P. & Raymond, K. N. (1979). Inorg. Chem. 18, 108–112. Google Scholar
Baughman, R. G., Brink, D. J., Butler, J. M. & New, P. R. (2000). Acta Cryst. C56, 528–531. CrossRef IUCr Journals Google Scholar
Brewer, G. A. & Sinn, E. (1981). Inorg. Chem. 20, 1823–1830. CrossRef Google Scholar
Bruker (2014). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Buvailo, A. I., Pavlishchuk, A. V., Penkova, L. V., Kotova, N. V. & Haukka, M. (2012). Acta Cryst. E68, m1480–m1481. CSD CrossRef IUCr Journals Google Scholar
Casellato, U., Vigato, P. A., Tamburini, S., Graziani, R. & Vidali, M. (1984). Inorg. Chim. Acta, 81, 47–54. CrossRef Google Scholar
Drovetskaia, T. V., Yashina, N. S., Leonova, T. V., Petrosyan, V. S., Lorberth, J., Wocadlo, S., Massa, W. & Pebler, J. (1996). J. Organomet. Chem. 507, 201–205. CrossRef Google Scholar
Due, L., Rasmussen, H. & Larsen, I. K. (1987). Acta Cryst. C43, 582–585. CrossRef IUCr Journals Google Scholar
Dzyuba, V. I., Koval, L. I., Bon, V. V. & Pekhnyo, V. I. (2010). Polyhedron, 29, 2900–2906. CrossRef Google Scholar
Fisher, D. C., Barclay-Peet, S. J., Balfe, C. A. & Raymond, K. N. (1989). Inorg. Chem. 28, 4399–4406. CSD CrossRef CAS Web of Science Google Scholar
Garlatti, El. T., Guidi, A., Chiesa, S., Ansbro, S., Baker, J., Ollivier, H., Mutka, H., Timco, D. I., Vitorica-Yrezabal, E., Pavarini, P., Santini, G., Amoretti, G., Winpenny, S. & Carretta, S. (2018). Chem. Sci. 9, 3555–3562. CrossRef Google Scholar
Gaynor, D., Starikova, Z. A., Haase, W. & Nolan, K. B. (2001). J. Chem. Soc. Dalton Trans. pp. 1578–1581. Web of Science CrossRef Google Scholar
Gaynor, D., Starikova, Z. A., Ostrovsky, S., Haase, W. & Nolan, K. B. (2002). Chem. Commun. pp. 506–507. Web of Science CSD CrossRef Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CSD CrossRef IUCr Journals Google Scholar
Harrison, P. G., King, T. J. & Richards, J. A. (1976). J. Chem. Soc. Dalton Trans. pp. 1414–1418. CrossRef Google Scholar
Hübschle, C. B., Sheldrick, G. M. & Dittrich, B. (2011). J. Appl. Cryst. 44, 1281–1284. Web of Science CrossRef IUCr Journals Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Lasri, J., Gupta, S., da Silva, M. F. C. G. & Pombeiro, A. J. L. (2012). Inorg. Chem. Commun. 18, 69–72. CrossRef Google Scholar
Li, Q., Guedes da Silva, M. F. C. & Pombeiro, A. J. L. (2004). Chem. Eur. J. 10, 1456–1462. CrossRef Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Marmion, C. J., Griffith, D. & Nolan, K. B. (2004). Eur. J. Inorg. Chem. pp. 3003–3016. Web of Science CrossRef Google Scholar
McDonald, C., Sanz, S., Brechin, E. K., Singh, M. K., Rajaraman, G., Gaynor, D. & Jones, L. F. (2014). RSC Adv. 4, 38182–38191. CrossRef Google Scholar
McDonald, C., Williams, D. W., Comar, P., Coles, S. J., Keene, T. D., Pitak, M. B., Brechin, E. K. & Jones, L. F. (2015). Dalton Trans. 44, 13359–13368. CrossRef Google Scholar
Mezei, G., Zaleski, C. M. & Pecoraro, V. L. (2007). Chem. Rev. 107, 4933–5003. Web of Science CrossRef PubMed CAS Google Scholar
Odarich, I. A., Pavlishchuk, A. V., Kalibabchuk, V. A. & Haukka, M. (2016). Acta Cryst. E72, 147–150. CrossRef IUCr Journals Google Scholar
Ostrowska, M., Fritsky, I. O., Gumienna-Kontecka, E. & Pavlishchuk, A. V. (2016). Coord. Chem. Rev. 327–328, 304–332. Web of Science CrossRef CAS Google Scholar
Pavlishchuk, A. V., Kolotilov, S. V., Zeller, M., Lofland, S. E. & Addison, A. W. (2018). Eur. J. Inorg. Chem. doi: 1002ejic.201800461. Google Scholar
Pavlishchuk, A. V., Kolotilov, S. V., Zeller, M., Lofland, S. E., Kiskin, M. A., Efimov, N. N., Ugolkova, E. A., Minin, V. V., Novotortsev, V. M. & Addison, A. W. (2017b). Eur. J. Inorg. Chem. pp. 4866–4878. CrossRef Google Scholar
Pavlishchuk, A. V., Kolotilov, S. V., Zeller, M., Lofland, S. E., Thompson, L. K., Addison, A. W. & Hunter, A. D. (2017a). Inorg. Chem. 56, 13152–13165. CrossRef Google Scholar
Pavlishchuk, A. V., Satska, Y. A., Kolotilov, S. V. & Fritsky, I. O. (2015). Curr. Inorg. Chem. 5, 5–25. CrossRef Google Scholar
Seitz, M., Oliver, A. G. & Raymond, K. N. (2007a). J. Am. Chem. Soc. 129, 11153–11160. CrossRef Google Scholar
Seitz, M., Pluth, M. D. & Raymond, K. N. (2007b). Inorg. Chem. 46, 351–353. CrossRef Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Smith, W. L. & Raymond, K. N. (1981). J. Am. Chem. Soc. 103, 3341–3349. CrossRef Google Scholar
Tedeschi, C., Azéma, J., Gornitzka, H., Tisnès, P. & Picard, C. (2003). Dalton Trans. pp. 1738–1745. CrossRef Google Scholar
Tirfoin, R., Chamoreau, L.-M., Li, Y., Fleury, B., Lisnard, L. & Journaux, Y. (2014). Dalton Trans. 43, 16805–16817. CrossRef Google Scholar
Vitórica-Yrezábal, I. J., Sava, D. F., Timco, G. A., Brown, M. S., Savage, M., Godfrey, H. G. W., Moreau, F., Schröder, M., Siperstein, F., Brammer, L., Yang, S., Attfield, M. P., McDouall, J. J. W. & Winpenny, R. E. P. (2017). Angew. Chem. Int. Ed. 56, 5527–5530. Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar