Crystal structures of (2,2′-bipyridyl-κ2N,N′)bis­[N,N-bis­(2-hydroxy­eth­yl)di­thio­carbamato-κ2S,S′]zinc dihydrate and (2,2′-bipyridyl-κ2N,N′)bis­[N-(2-hydroxy­eth­yl)-N-iso­propyl­dithio­carbamato-κ2S,S′]zinc

Safbri, S.A.M.; Halim, S.N.A.; Tiekink, E.R.T.

doi:10.1107/S2056989016000700

research communications

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 72| Part 2| February 2016| Pages 203-208

doi:10.1107/S2056989016000700

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Crystal structures of (2,2′-bipyridyl-κ²N,N′)bis[N,N-bis(2-hydroxyethyl)dithiocarbamato-κ²S,S′]zinc dihydrate and (2,2′-bipyridyl-κ²N,N′)bis[N-(2-hydroxyethyl)-N-isopropyldithiocarbamato-κ²S,S′]zinc

Siti Artikah M. Safbri,^a Siti Nadiah Abdul Halim ^a ^* and Edward R. T. Tiekink ^b ^*

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and ^bCentre for Crystalline Materials, Faculty of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
^*Correspondence e-mail: nadiahhalim@um.edu.my, edwardt@sunway.edu.my

Edited by M. Weil, Vienna University of Technology, Austria (Received 6 January 2016; accepted 14 January 2016; online 20 January 2016)

The common feature of the title compounds, [Zn(C₅H₁₀NO₂S₂)₂(C₁₀H₈N₂)]·2H₂O, (I), and [Zn(C₆H₁₂NOS₂)₂(C₁₀H₈N₂)], (II), is the location of the Zn^II atoms on a twofold rotation axis. Further, each Zn^II atom is chelated by two symmetry-equivalent and symmetrically coordinating dithiocarbamate ligands and a 2,2′-bipyridine ligand. The resulting N₂S₄ coordination geometry is based on a highly distorted octahedron in each case. In the molecular packing of (I), supramolecular ladders mediated by O—H⋯O hydrogen bonding are found whereby the uprights are defined by {⋯HO(water)⋯HO(hydroxy)⋯}_n chains parallel to the a axis and with the rungs defined by `Zn[S₂CN(CH₂CH₂)₂]₂'. The water molecules connect the ladders into a supramolecular layer parallel to the ab plane via water-O—H⋯S and pyridyl-C—H⋯O(water) interactions, with the connections between layers being of the type pyridyl-C—H⋯S. In (II), supramolecular layers parallel to the ab plane are sustained by hydroxy-O—H⋯S hydrogen bonds with connections between layers being of the type pyridyl-C—H⋯S.

Keywords: crystal structure; zinc; dithiocarbamate; hydrogen bonding.

CCDC references: 1447175; 1447174

1. Chemical context

The dithiocarbamate ligand ⁻S₂CNRR′, is well known as an effective chelator of transition metals, main group elements and lanthanides (Hogarth, 2005 ; Heard, 2005 ). The resulting four-membered MS₂C chelate ring has metalloaromatic character (Masui, 2001 ) and may act as an acceptor for C—H⋯π(chelate) interactions (Tiekink & Zukerman-Schpector, 2011 ) much in the same way as the now widely accepted C—H⋯π(arene) interactions. While other 1,1-dithiolate species may also form analogous interactions – these were probably first discussed in cadmium xanthate (⁻S₂COR) structures (Chen et al., 2003 ) – dithiocarbamate compounds have a greater propensity to form C—H⋯π(chelate) interactions, an observation related to the relatively greater contribution of the canonical structure ²⁻S₂C=N⁺RR′ to the overall electronic structure that enhances the electron density in the chelate ring (Tiekink & Zukerman-Schpector, 2011). This factor explains the strong chelation ability of the dithiocarbamate ligand and at the same time accounts for the reduced Lewis acidity of the metal cation in metal dithiocarbamates which reduces the ability of these species to form extended architectures in their interactions with Lewis bases. One way of overcoming the relative inability of the metal cation to engage in supramolecular association is to functionalize the dithiocarbamate ligand with, relevant to the present report, hydrogen-bonding functionality. In this context and as a continuation of earlier studies of the zinc-triad elements with dithiocarbamate ligands featuring hydroxyethyl groups capable of forming hydrogen-bonding interactions (Benson et al., 2007 ; Broker & Tiekink, 2011 ; Zhong et al., 2004 ; Tan et al., 2013 , 2016 ; Safbri et al., 2016 ; Howie et al., 2009 ), herein, the crystal and molecular structures of two new zinc dithiocarbamates, Zn[S₂CN(CH₂CH₂OH)₂]₂(bipy)·2H₂O, (I), and Zn[S₂CN(iPr)CH₂CH₂OH]₂(bipy), (II) where bipy = 2,2′-bipyridine are described.

2. Structural commentary

The molecular structure of the zinc compound in (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. The zinc cation is located on a twofold rotation axis and is chelated by two symmetry-equivalent dithiocarbamate ligands and the 2,2′-bipyridine ligand, which is bisected by the twofold rotation axis. The dithiocarbamate ligand chelates in a symmetric mode with the difference between the Zn—S_long and Zn—S_short bond lengths being 0.02 Å. The shorter Zn—S bond is approximately trans to a pyridyl-N atom. The N₂S₄ coordination geometry is based on an octahedron. In this description, one triangular face is defined by the S1, S2ⁱ and N2ⁱ atoms, and the other by the symmetry equivalent atoms [symmetry code: (i) $[{3\over 2}]$ − x, $[{1\over 2}]$ − y, z]. The dihedral angle between the two faces is 3.07 (4)° and the twist angle between them is approximately 35°, cf. 0 and 60° for ideal trigonal–prismatic and octahedral angles, respectively. The twist toward a trigonal prism is related in part to the acute bite angles subtended by the chelating ligands (Table 1).

Table 1
Geometric data (Å, °) for (I), unsolvated (I) and for (II)

Parameter	(I)^a	unsolvated (I)	(II)^b
Zn—S1	2.5361 (5)	2.4632 (12)	2.5068 (5)
Zn—S2	2.5163 (5)	2.5968 (13)	2.5247 (5)
Zn—S3	2.5361 (5)	2.5030 (12)	2.5068 (5)
Zn—S4	2.5163 (5)	2.6045 (13)	2.5247 (5)
Zn—N2	2.1682 (15)	2.157 (4)	2.1695 (15)
Zn—N3	2.1682 (15)	2.154 (3)	2.1695 (15)
C—S	1.7198 (18)–1.7253 (18)	1.696 (4)–1.726 (5)	1.7221 (19)–1.7301 (18)
S1—Zn—S2	71.376 (15)	70.46 (4)	71.289 (16)
S3—Zn—S4	71.376 (15)	70.15 (4)	71.289 (16)
N2—Zn—N2	75.71 (8)	74.72 (12)	75.08 (8)
Notes: (a) S3, S4 and N3 are S1ⁱ, S2ⁱ and N2ⁱ for (i) $[{3\over 2}]$ − x, $[{1\over 2}]$ − y, z; (b) S3, S4 and N3 are S1ⁱ, S2ⁱ and N2ⁱ for (i) 1 − x, y, $[{3\over 2}]$ − z.

Figure 1
The molecular structure of the zinc compound in (I)

, showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level; the water molecules of crystallization have been omitted. The unlabelled atoms are related by the symmetry operation $[{3\over 2}]$ − x, $[{1\over 2}]$ − y, z.

Compound (I) was characterized herein as a dihydrate and may be compared with an unsolvated literature precedent (Deng et al., 2007 ) for which selected geometric data are also collected in Table 1. First and foremost, the molecular symmetry observed in unsolvated (I) is lacking. Also, the range of Zn—S bond lengths is significantly broader at 0.14 Å, but the trend that the shorter Zn—S bonds are approximately trans to the pyridyl-N atoms persists. The dihedral angle between the trigonal faces is 5.33 (6)° and the twist between them is 31°, indicating an intermediate coordination geometry.

The molecule of compound (II) (Fig. 2) is also located about a twofold rotation axis and presents geometric features closely resembling those of (I), Table 1. The angle between the triangular faces is 1.50 (5)° and the twist angle is approximately 30°, again indicating a highly distorted coordination geometry.

Figure 2
The molecular structure of (II)

, showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level. The unlabelled atoms are related by the symmetry operation 1 − x, y, $[{3\over 2}]$ − z.

3. Supramolecular features

Geometric parameters characterizing the intermolecular interactions operating in the crystal structures of (I) and (II) are collected in Tables 2 and 3, respectively.

Table 2
Hydrogen-bond geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2O⋯O1	0.83 (2)	1.87 (2)	2.696 (2)	177 (3)
O1—H1O⋯O1W	0.83 (2)	1.88 (2)	2.7115 (19)	177 (2)
O1W—H1W⋯O2ⁱ	0.83 (2)	1.91 (2)	2.7216 (19)	166 (2)
O1W—H2W⋯S2ⁱⁱ	0.83 (2)	2.45 (2)	3.2733 (15)	170 (2)
C7—H7⋯O1Wⁱⁱⁱ	0.95	2.58	3.517 (2)	171
C6—H6⋯S2^iv	0.95	2.81	3.490 (2)	129
C9—H9⋯S1^v	0.95	2.84	3.6857 (18)	149
Symmetry codes: (i) x+1, y, z; (ii) $[x+{\script{1\over 2}}, -y+1, -z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z]$ ; (v) $[-x+{\script{3\over 2}}, y, z+{\script{1\over 2}}]$ .

Table 3
Hydrogen-bond geometry (Å, °) for (II)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯S2ⁱ	0.84 (2)	2.45 (2)	3.2437 (16)	160 (2)
C5—H5B⋯O1ⁱ	0.98	2.54	3.512 (2)	175
C9—H9⋯S2ⁱⁱ	0.95	2.86	3.550 (2)	130
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) -x+1, -y+2, -z+1.

In the molecular packing of (I), supramolecular ladders mediated by O—H⋯O hydrogen bonding are found. There is an intramolecular hydroxy-O—H⋯O(hydroxy) hydrogen bond as well as intermolecular hydroxy-O—H⋯O(water) and water-O—H⋯O(hydroxy) hydrogen bonds. This mode of association results in supramolecular {⋯HO(water)⋯HO(hydroxy)⋯HO(hydroxy)⋯}_n jagged chains parallel to the a axis that serve as the uprights in the supramolecular ladders whereby the rungs are defined by `Zn(S₂CN(CH₂CH₂)₂' (Fig. 3a). The water molecules are pivotal in connecting the ladders into a supramolecular layer parallel to the ab plane by forming water-O—H⋯S and pyridyl-C—H⋯O(water) interactions (Fig. 3b). The connections between layers to consolidate the three-dimensional architecture are of the type pyridyl-C—H⋯S (Fig. 3c).

Figure 3
Molecular packing in (I)

, showing (a) the supramolecular ladders aligned along the a axis and sustained by O—H⋯O hydrogen bonding, (b) the supramolecular layers parallel to the ab plane whereby the ladders in (a) are connected by O—H⋯S and C—H⋯O interactions, and (c) a view of the unit-cell contents in projection down the a axis, showing C—H⋯S interactions along the c axis connecting the layers in (b). The O—H⋯O, O—H⋯S, C—H⋯O and C—H⋯S interactions are shown as orange, blue, pink and green dashed lines, respectively.

Naturally, the molecular packing in the unsolvated form of (I) is distinct (Deng et al., 2007). However, a detailed analysis of the packing is restricted as one of the hydroxy groups is disordered over two sites. Further, there are large voids in the crystal structure, amounting to approximately 570 Å³ or 19.2% of the available volume (Spek, 2009 ). This is reflected in the crystal packing index of 59.2% which compares to 71.3% in (I). Globally, the crystal structure comprises alternating layers of hydrophilic and hydrophobic regions with the former arranged as supramolecular rods, indicating significant hydrogen bonding in this region of the crystal structure.

In the molecular packing of (II), hydroxy-O—H⋯S hydrogen bonds lead to supramolecular layers parallel to the ab plane (Fig. 4a). Additional stabilization to this arrangement is provided by methyl-C—H⋯O(hydroxy) interactions. Connections between layers to consolidate the three-dimensional packing are of the type pyridyl-C—H⋯S (Fig. 4b).

Figure 4
Molecular packing in (II)

, showing (a) the supramolecular layers parallel to the ab plane sustained by O—H⋯S and C—H⋯O interactions, and (b) a view of the unit-cell contents in projection down the b axis, showing C—H⋯S interactions along the c axis connecting the layers in (b). The O—H⋯S, C—H⋯O and C—H⋯S interactions are shown as orange, blue and pink dashed lines, respectively.

4. Database survey

Binary zinc dithiocarbamates are generally binuclear as a result of the presence of chelating and tridentate, μ₂-bridging ligands, leading to penta-coordinate geometries (Tiekink, 2003 ). The exceptional structures arise when the steric bulk of at least one of the terminal substituents is too great to allow for supramolecular association, e.g. R = cyclohexyl (Cox & Tiekink, 2009 ) and R = benzyl (Decken et al., 2004 ). However, there is a subtle energetic balance between the two forms as seen in the crystal structure of Zn[S₂CN(i-Bu)₂]₂ which comprises equal numbers of mono- and bi-nuclear molecules (Ivanov et al., 2005 ). As the R groups are generally aliphatic, there is limited scope for controlled supramolecular aggregation between the molecules. This changes in the case of the present study as at least one R group has an hydroxyethyl substituent. Indeed, a rich tapestry of structures have been observed for zinc compounds with this family of dithiocarbamate ligands.

The common feature of the molecular structures of the known binary species, Zn[S₂NC(R)CH₂CH₂OH]₂, is the adoption of a binuclear motif (Benson et al., 2007; Tan et al., 2015 ). In the molecular packing of these species, when R = CH₂CH₂OH, a three-dimensional architecture is constructed based on hydrogen bonding (Benson et al., 2007). When the hydrogen-bonding potential is reduced, as in the case when R = Et, linear supramolecular chains are formed (Benson et al., 2007). When R = Me, and in the 2:1 adduct with the bridging ligand (3-pyridyl)CH₂N(H)C(=O)C(=O)N(H)CH₂(3-pyridyl), interwoven supramolecular chains are formed based on hydrogen bonding (Poplaukhin & Tiekink, 2010 ). Extensive hydrogen bonding is also noted in co-crystals, e.g. for R = Me in the 2:1 adduct with (3-pyridyl)CH₂N(H)C(=S)C(=S)N(H)CH₂(3-pyridyl), a 2:1 co-crystal with S₈ has been characterized in which a two-dimensional array sustained by O—H⋯O hydrogen bonding is found (Poplaukhin et al., 2012 ). From the foregoing, it is clear that a rich structural chemistry exists for these compounds, well worthy of further investigation. Complementing these interests are the observations that zinc compounds with these ligands (Tan et al., 2015), along with gold (Jamaludin et al., 2013 ) and bismuth (Ishak et al., 2014 ) exhibit exciting anti-cancer potential.

5. Synthesis and crystallization

The potassium salts of the dithiocarbamate anions (Howie et al., 2008 ; Tan et al., 2013) and zinc compounds (Benson et al., 2007) were prepared in accord with the literature methods. The 1:1 adducts with 2,2′-bipyridine were prepared in the following manner. Zn[S₂CN(CH₂CH₂OH)₂]₂ (0.20 g, 0.47 mmol) and 2,2′-bipyridine (Sigma Aldrich; 0.07 g, 0.47 mmol) were dissolved in acetone (30 ml) and ethanol (10 ml), respectively. The solution of 2,2′-bipyridine was added dropwise into the other solution with stirring for about 30 mins, resulting in a change from a colourless to a light-yellow solution. The mixture was left to stand to allow for crystallization and crystals of (I) for X-ray analysis were harvested directly. Compound (II) was prepared and harvested similarly from the reaction of Zn[S₂CN(iPr)CH₂CH₂OH]₂ (0.20 g, 0.47 mmol) in chloroform (30 ml) and 2,2′-bipyridine (0.07 g, 0.47 mmol) in acetone (10 ml).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4. For each of (I) and (II), carbon-bound H atoms were placed in calculated positions (C—H = 0.95–1.00 Å) and were included in the refinement in the riding-model approximation, with U_iso(H) set to 1.2–1.5U_eq(C). The O-bound H atoms were located in a difference Fourier map but were refined with a distance restraint of O—H = 0.84±0.01 Å, and with U_iso(H) set to 1.5U_eq(O).

Table 4
Experimental details

	(I)	(II)
Crystal data
Chemical formula	[Zn(C₅H₁₀NO₂S₂)₂(C₁₀H₈N₂)]·2H₂O	[Zn(C₆H₁₂NOS₂)₂(C₁₀H₈N₂)]
M_r	618.10	578.12
Crystal system, space group	Orthorhombic, Pccn	Monoclinic, C2/c
Temperature (K)	100	100
a, b, c (Å)	6.7730 (3), 23.1063 (11), 16.9483 (8)	19.4997 (11), 9.0027 (5), 15.5352 (8)
α, β, γ (°)	90, 90, 90	90, 98.031 (5), 90
V (Å³)	2652.4 (2)	2700.5 (3)
Z	4	4
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	1.28	1.25
Crystal size (mm)	0.40 × 0.30 × 0.20	0.25 × 0.25 × 0.15

Data collection
Diffractometer	Agilent SuperNova Dual diffractometer with an Atlas detector	Agilent SuperNova Dual diffractometer with Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2012 )	Multi-scan (CrysAlis PRO; Agilent, 2012)
T_min, T_max	0.778, 1.000	0.737, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	21039, 3047, 2607	11190, 3095, 2657
R_int	0.049	0.048
(sin θ/λ)_max (Å⁻¹)	0.650	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.066, 1.02	0.030, 0.073, 1.03
No. of reflections	3047	3095
No. of parameters	171	155
No. of restraints	4	1
Δρ_max, Δρ_min (e Å⁻³)	0.39, −0.34	0.38, −0.35
Computer programs: CrysAlis PRO (Agilent, 2012), SHELXS97 (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 1447175; 1447174

Crystal structure: contains datablocks I, II, global. DOI: 10.1107/S2056989016000700/wm5262sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989016000700/wm5262Isup2.hkl

Structure factors: contains datablock II. DOI: 10.1107/S2056989016000700/wm5262IIsup3.hkl

checkCIF report

Chemical context top

The dithiocarbamate ligand ^-S₂CNRR', is well known as an effective chelator of transition metals, main group elements and lanthanides (Hogarth, 2005; Heard 2005). The resulting four-membered MS₂C chelate ring has metalloaromatic character (Masui, 2001) and may act as an acceptor for C—H···π(chelate) interactions (Tiekink & Zukerman-Schpector, 2011) much in the same way as the now widely accepted C—H···π(arene) interactions. While other 1,1-dithiolate species may also form analogous interactions – these were probably first discussed in cadmium xanthate (^-S₂COR) structures (Chen et al., 2003) – dithiocarbamate compounds have a greater propensity to form C—H···π(chelate) interactions, an observation related to the relatively greater contribution of the canonical structure ^2-S₂C═N⁺RR' to the overall electronic structure that enhances the electron density in the chelate ring (Tiekink & Zukerman-Schpector, 2011). This factor explains the strong chelation ability of the dithiocarbamate ligand and at the same time accounts for the reduced Lewis acidity of the metal cation in metal dithiocarbamates which reduces the ability of these species to form extended architectures in their interactions with Lewis bases. One way of overcoming the relative inability of the metal cation to engage in supramolecular association is to functionalize the dithiocarbamate ligand with, relevant to the present report, hydrogen-bonding functionality. In this context and as a continuation of earlier studies of the zinc-triad elements with dithiocarbamate ligands featuring hydroxyethyl groups capable of forming hydrogen-bonding interactions (Benson et al., 2007; Broker & Tiekink, 2011; Zhong et al., 2004; Tan et al., 2013, 2016; Safbri et al., 2016; Howie et al., 2009), herein, the crystal and molecular structures of two new zinc dithiocarbamates, Zn[S₂CN(CH₂CH₂OH)₂]₂(bipy)·2H₂O, (I), and Zn[S₂CN(iPr)CH₂CH₂OH]₂(bipy), (II) where bipy = 2,2'-bipyridine are described.

Structural commentary top

The molecular structure of the zinc compound in (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. The zinc cation is located on a twofold rotation axis and is chelated by two symmetry-equivalent dithiocarbamate ligands and the 2,2'-bipyridine ligand, which is bisected by the twofold rotation axis. The dithiocarbamate ligand chelates in a symmetric mode with the difference between the Zn—S_long and Zn—S_short bond lengths being 0.02 Å. The shorter Zn—S bond is approximately trans to a pyridyl-N atom. The N₂S₄ coordination geometry is based on an octahedron. In this description, one triangular face is defined by the S1, S2ⁱ and N2ⁱ atoms, and the other by the symmetry equivalent atoms [symmetry code: (i) 3/2 - x, 1/2 - y, z]. The dihedral angle between the two faces is 3.07 (4)° and the twist angle between them is approximately 35°, cf. 0 and 60° for ideal trigonal–prismatic and octahedral angles, respectively. The twist toward a trigonal prism is related in part to the acute bite angles subtended by the chelating ligands (Table 1).

Compound (I) was characterized herein as a dihydrate and may be compared with an unsolvated literature precedent (Deng et al., 2007) for which selected geometric data are also collected in Table 1. First and foremost, the molecular symmetry observed in unsolvated (I) is lacking. Also, the range of Zn—S bond lengths is significantly broader at 0.14 Å, but the trend that the shorter Zn—S bonds are approximately trans to the pyridyl-N atoms persists. The dihedral angle between the trigonal faces is 5.33 (6)° and the twist between them is 31°, indicating an intermediate coordination geometry.

The molecule of compound (II) is also located about a twofold rotation axis and presents geometric features closely resembling those of (I), Table 1. The angle between the triangular faces is 1.50 (5)° and the twist angle is approximately 30°, again indicating a highly distorted coordination geometry.

Supramolecular features top

Geometric parameters characterizing the intermolecular interactions operating in the crystal structures of (I) and (II) are collected in Tables 2 and 3, respectively.

In the molecular packing of (I), supramolecular ladders mediated by O—H···O hydrogen bonding are found. There is an intramolecular hydroxy-O—H···O(hydroxy) hydrogen bond as well as intermolecular hydroxy-O—H···O(water) and water-O—H···O(hydroxy) hydrogen bonds. This mode of association results in supramolecular {···HO(water)···HO(hydroxy)···HO(hydroxy)···}_n jagged chains parallel to the a axis that serve as the uprights in the supramolecular ladders whereby the rungs are defined by `Zn(S₂CN(CH₂CH₂)₂' (Fig. 3a). The water molecules are pivotal in connecting the ladders into a supramolecular layer parallel to the ab plane by forming water-O—H···S and pyridyl-C—H···O(water) interactions (Fig. 3b). The connections between layers to consolidate the three-dimensional architecture are of the type pyridyl-C—H···S (Fig. 3c).

Naturally, the molecular packing in the unsolvated form of (I) is distinct (Deng et al., 2007). However, a detailed analysis of the packing is restricted as one of the hydroxy groups is disordered over two sites. Further, there are large voids in the crystal structure, amounting to approximately 570 Å³ or 19.2% of the available volume (Spek, 2009). This is reflected in the crystal packing index of 59.2% which compares to 71.3% in (I). Globally, the crystal structure comprises alternating layers of hydrophilic and hydrophobic regions with the former arranged as supramolecular rods, indicating significant hydrogen bonding in this region of the crystal structure.

In the molecular packing of (II), hydroxy-O—H···S hydrogen bonds lead to supramolecular layers parallel to the ab plane (Fig. 4a). Additional stabilization to this arrangement is provided by methyl-C—H···O(hydroxy) interactions. Connections between layers to consolidate the three-dimensional packing are of the type pyridyl-C—H···S (Fig. 4b).

Database survey top

Binary zinc dithiocarbamates are generally binuclear as a result of the presence of chelating and tridentate, µ₂-bridging ligands, leading to penta-coordinate geometries (Tiekink, 2003). The exceptional structures arise when the steric bulk of at least one of the terminal substituents is too great to allow for supramolecular association, e.g. R = cyclohexyl (Cox & Tiekink, 2009) and R = benzyl (Decken et al. 2004). However, there is a subtle energetic balance between the two forms as seen in the crystal structure of Zn[S₂CN(i-Bu)₂]₂ which comprises equal numbers of mono- and bi-nuclear molecules (Ivanov et al., 2005). As the R groups are generally aliphatic, there is limited scope for controlled supramolecular aggregation between the molecules. This changes in the case of the present study as at least one R group has an hydroxyethyl substituent. Indeed, a rich tapestry of structures have been observed for zinc compounds with this family of dithiocarbamate ligands.

The common feature of the molecular structures of the known binary species, Zn[S₂NC(R)CH₂CH₂OH]₂, is the adoption of a binuclear motif (Benson et al., 2007; Tan et al., 2015). In the molecular packing of these species, when R = CH₂CH₂OH, a three-dimensional architecture is constructed based on hydrogen bonding (Benson et al., 2007). When the hydrogen-bonding potential is reduced, as in the case when R = Et, linear supramolecular chains are formed (Benson et al., 2007). When R = Me, and in the 2:1 adduct with the bridging ligand (3-pyridyl)CH₂N(H)C(═O)C(═O)N(H)CH₂(3-pyridyl), interwoven supramolecular chains are formed based on hydrogen bonding (Poplaukhin & Tiekink, 2010). Extensive hydrogen bonding is also noted in co-crystals, e.g. for R = Me in the 2:1 adduct with (3-pyridyl)CH₂N(H)C(═S)C(═S)N(H)CH₂(3-pyridyl), a 2:1 co-crystal with S₈ has been characterized in which a two-dimensional array sustained by O—H···O hydrogen bonding is found (Poplaukhin et al., 2012). From the foregoing, it is clear that a rich structural chemistry exists for these compounds, well worthy of further investigation. Complementing these interests are the observations that zinc compounds with these ligands (Tan et al., 2015), along with gold (Jamaludin et al., 2013) and bismuth (Ishak et al., 2014) exhibit exciting anti-cancer potential.

Synthesis and crystallization top

The potassium salts of the dithiocarbamate anions (Howie et al., 2008; Tan et al., 2013) and zinc compounds (Benson et al., 2007) were prepared in accord with the literature methods. The 1:1 adducts with 2,2'-bipyridine were prepared in the following manner. Zn[S₂CN(CH₂CH₂OH)₂]₂ (0.20 g, 0.47 mmol) and 2,2'-bipyridine (Sigma Aldrich; 0.07 g, 0.47 mmol) were dissolved in acetone (30 ml) and ethanol (10 ml), respectively. The solution of 2,2'-bipyridine was added dropwise into the other solution with stirring for about 30 mins, resulting in a change from a colourless to a light-yellow solution. The mixture was left to stand to allow for crystallization and crystals of (I) for X-ray analysis were harvested directly. Compound (II) was prepared and harvested similarly from the reaction of Zn[S₂CN(iPr)CH₂CH₂OH]₂ (0.20 g, 0.47 mmol) in chloroform (30 ml) and 2,2'-bipyridine (0.07 g, 0.47 mmol) in acetone (10 ml).

Refinement top

Structure description top

The molecular structure of the zinc compound in (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. The zinc cation is located on a twofold rotation axis and is chelated by two symmetry-equivalent dithiocarbamate ligands and the 2,2'-bipyridine ligand, which is bisected by the twofold rotation axis. The dithiocarbamate ligand chelates in a symmetric mode with the difference between the Zn—S_long and Zn—S_short bond lengths being 0.02 Å. The shorter Zn—S bond is approximately trans to a pyridyl-N atom. The N₂S₄ coordination geometry is based on an octahedron. In this description, one triangular face is defined by the S1, S2ⁱ and N2ⁱ atoms, and the other by the symmetry equivalent atoms [symmetry code: (i) 3/2 - x, 1/2 - y, z]. The dihedral angle between the two faces is 3.07 (4)° and the twist angle between them is approximately 35°, cf. 0 and 60° for ideal trigonal–prismatic and octahedral angles, respectively. The twist toward a trigonal prism is related in part to the acute bite angles subtended by the chelating ligands (Table 1).

Compound (I) was characterized herein as a dihydrate and may be compared with an unsolvated literature precedent (Deng et al., 2007) for which selected geometric data are also collected in Table 1. First and foremost, the molecular symmetry observed in unsolvated (I) is lacking. Also, the range of Zn—S bond lengths is significantly broader at 0.14 Å, but the trend that the shorter Zn—S bonds are approximately trans to the pyridyl-N atoms persists. The dihedral angle between the trigonal faces is 5.33 (6)° and the twist between them is 31°, indicating an intermediate coordination geometry.

Geometric parameters characterizing the intermolecular interactions operating in the crystal structures of (I) and (II) are collected in Tables 2 and 3, respectively.

Naturally, the molecular packing in the unsolvated form of (I) is distinct (Deng et al., 2007). However, a detailed analysis of the packing is restricted as one of the hydroxy groups is disordered over two sites. Further, there are large voids in the crystal structure, amounting to approximately 570 Å³ or 19.2% of the available volume (Spek, 2009). This is reflected in the crystal packing index of 59.2% which compares to 71.3% in (I). Globally, the crystal structure comprises alternating layers of hydrophilic and hydrophobic regions with the former arranged as supramolecular rods, indicating significant hydrogen bonding in this region of the crystal structure.

The common feature of the molecular structures of the known binary species, Zn[S₂NC(R)CH₂CH₂OH]₂, is the adoption of a binuclear motif (Benson et al., 2007; Tan et al., 2015). In the molecular packing of these species, when R = CH₂CH₂OH, a three-dimensional architecture is constructed based on hydrogen bonding (Benson et al., 2007). When the hydrogen-bonding potential is reduced, as in the case when R = Et, linear supramolecular chains are formed (Benson et al., 2007). When R = Me, and in the 2:1 adduct with the bridging ligand (3-pyridyl)CH₂N(H)C(═O)C(═O)N(H)CH₂(3-pyridyl), interwoven supramolecular chains are formed based on hydrogen bonding (Poplaukhin & Tiekink, 2010). Extensive hydrogen bonding is also noted in co-crystals, e.g. for R = Me in the 2:1 adduct with (3-pyridyl)CH₂N(H)C(═S)C(═S)N(H)CH₂(3-pyridyl), a 2:1 co-crystal with S₈ has been characterized in which a two-dimensional array sustained by O—H···O hydrogen bonding is found (Poplaukhin et al., 2012). From the foregoing, it is clear that a rich structural chemistry exists for these compounds, well worthy of further investigation. Complementing these interests are the observations that zinc compounds with these ligands (Tan et al., 2015), along with gold (Jamaludin et al., 2013) and bismuth (Ishak et al., 2014) exhibit exciting anti-cancer potential.

Synthesis and crystallization top

The potassium salts of the dithiocarbamate anions (Howie et al., 2008; Tan et al., 2013) and zinc compounds (Benson et al., 2007) were prepared in accord with the literature methods. The 1:1 adducts with 2,2'-bipyridine were prepared in the following manner. Zn[S₂CN(CH₂CH₂OH)₂]₂ (0.20 g, 0.47 mmol) and 2,2'-bipyridine (Sigma Aldrich; 0.07 g, 0.47 mmol) were dissolved in acetone (30 ml) and ethanol (10 ml), respectively. The solution of 2,2'-bipyridine was added dropwise into the other solution with stirring for about 30 mins, resulting in a change from a colourless to a light-yellow solution. The mixture was left to stand to allow for crystallization and crystals of (I) for X-ray analysis were harvested directly. Compound (II) was prepared and harvested similarly from the reaction of Zn[S₂CN(iPr)CH₂CH₂OH]₂ (0.20 g, 0.47 mmol) in chloroform (30 ml) and 2,2'-bipyridine (0.07 g, 0.47 mmol) in acetone (10 ml).

Refinement details top

Computing details top

For both compounds, 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: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. The molecular structure of the zinc compound in (I), showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level; the water molecules of crystallization have been omitted. The unlabelled atoms are related by the symmetry operation (3/2 - x, 1/2 - y, z).
	Fig. 2. The molecular structure of (II), showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level. The unlabelled atoms are related by the symmetry operation (1 - x, y, 3/2 - z).
	Fig. 3. Molecular packing in (I), showing (a) the supramolecular ladders aligned along the a axis and sustained by O—H···O hydrogen bonding, (b) the supramolecular layers parallel to the ab plane whereby the ladders in (a) are connected by O—H···S and C—H···O interactions, and (c) a view of the unit-cell contents in projection down the a axis, showing C—H···S interactions along the c axis connecting the layers in (b). The O—H···O, O—H···S, C—H···O and C—H···S interactions are shown as orange, blue, pink and green dashed lines, respectively.
	Fig. 4. Molecular packing in (II), showing (a) the supramolecular layers parallel to the ab plane sustained by O—H···S and C—H···O interactions, and (b) a view of the unit-cell contents in projection down the b axis, showing C—H···S interactions along the c axis connecting the layers in (b). The O—H···S, C—H···O and C—H···S interactions are shown as orange, blue and pink dashed lines, respectively.

(I) (2,2'-Bipyridyl-κ²N,N')bis[N,N-bis(2-hydroxyethyl)dithiocarbamato-κ²S,S']zinc dihydrate top

Crystal data top

[Zn(C₅H₁₀NO₂S₂)₂(C₁₀H₈N₂)]·2H₂O	D_x = 1.548 Mg m⁻³
M_r = 618.10	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pccn	Cell parameters from 5870 reflections
a = 6.7730 (3) Å	θ = 2.6–27.5°
b = 23.1063 (11) Å	µ = 1.28 mm⁻¹
c = 16.9483 (8) Å	T = 100 K
V = 2652.4 (2) Å³	Prism, light-yellow
Z = 4	0.40 × 0.30 × 0.20 mm
F(000) = 1288

Data collection top

Agilent SuperNova Dual diffractometer with an Atlas detector	3047 independent reflections
Radiation source: SuperNova (Mo) X-ray Source	2607 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.049
Detector resolution: 10.4041 pixels mm^-1	θ_max = 27.5°, θ_min = 2.6°
ω scan	h = −8→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −30→29
T_min = 0.778, T_max = 1.000	l = −22→21
21039 measured reflections

Refinement top

Refinement on F²	4 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.027	w = 1/[σ²(F_o²) + (0.0256P)² + 1.8882P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.066	(Δ/σ)_max = 0.001
S = 1.02	Δρ_max = 0.39 e Å⁻³
3047 reflections	Δρ_min = −0.34 e Å⁻³
171 parameters

Crystal data top

[Zn(C₅H₁₀NO₂S₂)₂(C₁₀H₈N₂)]·2H₂O	V = 2652.4 (2) Å³
M_r = 618.10	Z = 4
Orthorhombic, Pccn	Mo Kα radiation
a = 6.7730 (3) Å	µ = 1.28 mm⁻¹
b = 23.1063 (11) Å	T = 100 K
c = 16.9483 (8) Å	0.40 × 0.30 × 0.20 mm

Data collection top

Agilent SuperNova Dual diffractometer with an Atlas detector	3047 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	2607 reflections with I > 2σ(I)
T_min = 0.778, T_max = 1.000	R_int = 0.049
21039 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.027	171 parameters
wR(F²) = 0.066	4 restraints
S = 1.02	Δρ_max = 0.39 e Å⁻³
3047 reflections	Δρ_min = −0.34 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
Zn	0.7500	0.2500	0.25218 (2)	0.01179 (9)
S1	0.88162 (6)	0.32477 (2)	0.15608 (3)	0.01323 (11)
S2	0.48554 (6)	0.32443 (2)	0.22814 (3)	0.01403 (11)
N1	0.5960 (2)	0.39933 (6)	0.11619 (8)	0.0123 (3)
N2	0.5960 (2)	0.21427 (6)	0.35319 (8)	0.0122 (3)
O1	0.8068 (2)	0.51852 (6)	0.09325 (9)	0.0221 (3)
H1O	0.899 (3)	0.5406 (9)	0.1051 (14)	0.033*
O2	0.4459 (2)	0.52831 (6)	0.15907 (9)	0.0273 (3)
H2O	0.559 (2)	0.5263 (11)	0.1401 (14)	0.041*
O1W	1.1132 (2)	0.58995 (6)	0.12670 (8)	0.0202 (3)
H1W	1.225 (2)	0.5761 (10)	0.1348 (14)	0.030*
H2W	1.096 (3)	0.6133 (8)	0.1634 (10)	0.030*
C1	0.6497 (3)	0.35475 (8)	0.16217 (10)	0.0123 (4)
C2	0.7307 (3)	0.42078 (8)	0.05455 (10)	0.0151 (4)
H2A	0.6521	0.4409	0.0137	0.018*
H2B	0.7958	0.3872	0.0291	0.018*
C3	0.8882 (3)	0.46162 (8)	0.08437 (11)	0.0178 (4)
H3A	0.9390	0.4478	0.1358	0.021*
H3B	0.9996	0.4627	0.0466	0.021*
C4	0.3983 (3)	0.42555 (8)	0.12367 (11)	0.0151 (4)
H4A	0.3018	0.3948	0.1369	0.018*
H4B	0.3597	0.4422	0.0721	0.018*
C5	0.3875 (3)	0.47266 (8)	0.18629 (12)	0.0200 (4)
H5A	0.2503	0.4750	0.2061	0.024*
H5B	0.4731	0.4615	0.2311	0.024*
C6	0.4312 (3)	0.18264 (8)	0.34890 (11)	0.0161 (4)
H6	0.3897	0.1689	0.2988	0.019*
C7	0.3183 (3)	0.16904 (8)	0.41461 (11)	0.0170 (4)
H7	0.2017	0.1465	0.4096	0.020*
C8	0.3791 (3)	0.18905 (8)	0.48773 (11)	0.0154 (4)
H8	0.3034	0.1810	0.5336	0.019*
C9	0.5519 (3)	0.22098 (8)	0.49310 (10)	0.0140 (4)
H9	0.5975	0.2346	0.5428	0.017*
C10	0.6574 (2)	0.23279 (7)	0.42442 (10)	0.0115 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn	0.01403 (15)	0.01109 (16)	0.01025 (15)	0.00054 (11)	0.000	0.000
S1	0.0126 (2)	0.0131 (2)	0.0140 (2)	0.00237 (17)	0.00144 (16)	0.00154 (16)
S2	0.0142 (2)	0.0131 (2)	0.0149 (2)	0.00035 (17)	0.00304 (17)	0.00135 (16)
N1	0.0122 (7)	0.0119 (7)	0.0127 (7)	0.0013 (6)	−0.0001 (6)	−0.0003 (6)
N2	0.0126 (7)	0.0115 (7)	0.0124 (7)	0.0007 (6)	−0.0003 (6)	−0.0006 (6)
O1	0.0191 (7)	0.0139 (7)	0.0332 (8)	−0.0013 (6)	0.0019 (6)	0.0008 (6)
O2	0.0186 (7)	0.0141 (7)	0.0491 (10)	0.0024 (6)	0.0051 (7)	−0.0030 (6)
O1W	0.0197 (7)	0.0191 (8)	0.0219 (7)	0.0019 (6)	0.0003 (6)	−0.0048 (6)
C1	0.0142 (9)	0.0118 (9)	0.0110 (8)	−0.0004 (7)	−0.0005 (7)	−0.0028 (6)
C2	0.0182 (9)	0.0148 (9)	0.0123 (9)	0.0008 (7)	0.0018 (7)	0.0027 (7)
C3	0.0151 (9)	0.0147 (10)	0.0236 (10)	0.0024 (7)	0.0032 (7)	0.0034 (8)
C4	0.0130 (9)	0.0145 (9)	0.0176 (9)	0.0033 (7)	−0.0019 (7)	0.0004 (7)
C5	0.0168 (9)	0.0196 (10)	0.0235 (10)	0.0026 (8)	0.0020 (8)	−0.0027 (8)
C6	0.0169 (9)	0.0149 (9)	0.0164 (9)	−0.0014 (7)	−0.0036 (7)	−0.0019 (7)
C7	0.0131 (9)	0.0150 (10)	0.0228 (10)	−0.0033 (7)	−0.0017 (7)	0.0023 (8)
C8	0.0137 (9)	0.0157 (9)	0.0169 (9)	0.0007 (7)	0.0027 (7)	0.0047 (7)
C9	0.0159 (9)	0.0131 (9)	0.0129 (9)	0.0007 (7)	−0.0003 (7)	0.0017 (7)
C10	0.0115 (8)	0.0093 (8)	0.0136 (9)	0.0004 (7)	−0.0017 (7)	0.0001 (7)

Geometric parameters (Å, º) top

Zn—N2ⁱ	2.1682 (15)	C2—C3	1.511 (3)
Zn—N2	2.1682 (14)	C2—H2A	0.9900
Zn—S2ⁱ	2.5163 (5)	C2—H2B	0.9900
Zn—S2	2.5163 (5)	C3—H3A	0.9900
Zn—S1ⁱ	2.5361 (5)	C3—H3B	0.9900
Zn—S1	2.5361 (5)	C4—C5	1.522 (3)
S1—C1	1.7198 (18)	C4—H4A	0.9900
S2—C1	1.7253 (18)	C4—H4B	0.9900
N1—C1	1.342 (2)	C5—H5A	0.9900
N1—C2	1.473 (2)	C5—H5B	0.9900
N1—C4	1.475 (2)	C6—C7	1.387 (3)
N2—C6	1.336 (2)	C6—H6	0.9500
N2—C10	1.347 (2)	C7—C8	1.385 (3)
O1—C3	1.434 (2)	C7—H7	0.9500
O1—H1O	0.832 (10)	C8—C9	1.386 (3)
O2—C5	1.422 (2)	C8—H8	0.9500
O2—H2O	0.830 (10)	C9—C10	1.393 (2)
O1W—H1W	0.835 (10)	C9—H9	0.9500
O1W—H2W	0.832 (9)	C10—C10ⁱ	1.485 (3)

N2ⁱ—Zn—N2	75.71 (8)	H2A—C2—H2B	107.6
N2ⁱ—Zn—S2ⁱ	92.61 (4)	O1—C3—C2	109.67 (15)
N2—Zn—S2ⁱ	102.13 (4)	O1—C3—H3A	109.7
N2ⁱ—Zn—S2	102.13 (4)	C2—C3—H3A	109.7
N2—Zn—S2	92.61 (4)	O1—C3—H3B	109.7
S2ⁱ—Zn—S2	161.36 (2)	C2—C3—H3B	109.7
N2ⁱ—Zn—S1ⁱ	159.33 (4)	H3A—C3—H3B	108.2
N2—Zn—S1ⁱ	94.50 (4)	N1—C4—C5	113.40 (15)
S2ⁱ—Zn—S1ⁱ	71.377 (15)	N1—C4—H4A	108.9
S2—Zn—S1ⁱ	96.394 (15)	C5—C4—H4A	108.9
N2ⁱ—Zn—S1	94.50 (4)	N1—C4—H4B	108.9
N2—Zn—S1	159.33 (4)	C5—C4—H4B	108.9
S2ⁱ—Zn—S1	96.394 (15)	H4A—C4—H4B	107.7
S2—Zn—S1	71.376 (15)	O2—C5—C4	114.03 (16)
S1ⁱ—Zn—S1	100.09 (2)	O2—C5—H5A	108.7
C1—S1—Zn	85.11 (6)	C4—C5—H5A	108.7
C1—S2—Zn	85.62 (6)	O2—C5—H5B	108.7
C1—N1—C2	120.14 (14)	C4—C5—H5B	108.7
C1—N1—C4	120.76 (15)	H5A—C5—H5B	107.6
C2—N1—C4	119.02 (14)	N2—C6—C7	122.73 (17)
C6—N2—C10	118.74 (15)	N2—C6—H6	118.6
C6—N2—Zn	124.56 (12)	C7—C6—H6	118.6
C10—N2—Zn	115.97 (11)	C8—C7—C6	118.61 (17)
C3—O1—H1O	107.5 (17)	C8—C7—H7	120.7
C5—O2—H2O	109.3 (18)	C6—C7—H7	120.7
H1W—O1W—H2W	105 (2)	C7—C8—C9	119.16 (17)
N1—C1—S1	121.46 (13)	C7—C8—H8	120.4
N1—C1—S2	120.88 (13)	C9—C8—H8	120.4
S1—C1—S2	117.64 (10)	C8—C9—C10	118.85 (16)
N1—C2—C3	114.22 (15)	C8—C9—H9	120.6
N1—C2—H2A	108.7	C10—C9—H9	120.6
C3—C2—H2A	108.7	N2—C10—C9	121.89 (16)
N1—C2—H2B	108.7	N2—C10—C10ⁱ	115.54 (10)
C3—C2—H2B	108.7	C9—C10—C10ⁱ	122.56 (11)

C2—N1—C1—S1	4.9 (2)	N1—C4—C5—O2	85.17 (19)
C4—N1—C1—S1	−178.34 (12)	C10—N2—C6—C7	1.4 (3)
C2—N1—C1—S2	−173.68 (12)	Zn—N2—C6—C7	−168.48 (14)
C4—N1—C1—S2	3.1 (2)	N2—C6—C7—C8	−0.1 (3)
Zn—S1—C1—N1	−173.88 (14)	C6—C7—C8—C9	−1.1 (3)
Zn—S1—C1—S2	4.70 (9)	C7—C8—C9—C10	1.1 (3)
Zn—S2—C1—N1	173.85 (14)	C6—N2—C10—C9	−1.4 (3)
Zn—S2—C1—S1	−4.73 (9)	Zn—N2—C10—C9	169.27 (13)
C1—N1—C2—C3	−81.8 (2)	C6—N2—C10—C10ⁱ	179.44 (18)
C4—N1—C2—C3	101.31 (18)	Zn—N2—C10—C10ⁱ	−9.8 (2)
N1—C2—C3—O1	−80.47 (19)	C8—C9—C10—N2	0.2 (3)
C1—N1—C4—C5	86.7 (2)	C8—C9—C10—C10ⁱ	179.3 (2)
C2—N1—C4—C5	−96.50 (19)

Symmetry code: (i) −x+3/2, −y+1/2, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O1	0.83 (2)	1.87 (2)	2.696 (2)	177 (3)
O1—H1O···O1W	0.83 (2)	1.88 (2)	2.7115 (19)	177 (2)
O1W—H1W···O2ⁱⁱ	0.83 (2)	1.91 (2)	2.7216 (19)	166 (2)
O1W—H2W···S2ⁱⁱⁱ	0.83 (2)	2.45 (2)	3.2733 (15)	170 (2)
C7—H7···O1W^iv	0.95	2.58	3.517 (2)	171
C6—H6···S2^v	0.95	2.81	3.490 (2)	129
C9—H9···S1^vi	0.95	2.84	3.6857 (18)	149

Symmetry codes: (ii) x+1, y, z; (iii) x+1/2, −y+1, −z+1/2; (iv) −x+1, y−1/2, −z+1/2; (v) −x+1/2, −y+1/2, z; (vi) −x+3/2, y, z+1/2.

(II) (2,2'-Bipyridyl-κ²N,N')bis[N-(2-hydroxyethyl)-N-isopropyldithiocarbamato-κ²S,S']zinc top

Crystal data top

[Zn(C₆H₁₂NOS₂)₂(C₁₀H₈N₂)]	F(000) = 1208
M_r = 578.12	D_x = 1.422 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 19.4997 (11) Å	Cell parameters from 3771 reflections
b = 9.0027 (5) Å	θ = 2.3–27.5°
c = 15.5352 (8) Å	µ = 1.25 mm⁻¹
β = 98.031 (5)°	T = 100 K
V = 2700.5 (3) Å³	Prism, light-yellow
Z = 4	0.25 × 0.25 × 0.15 mm

Data collection top

Agilent SuperNova Dual diffractometer with Atlas detector	3095 independent reflections
Radiation source: SuperNova (Mo) X-ray Source	2657 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.048
Detector resolution: 10.4041 pixels mm^-1	θ_max = 27.5°, θ_min = 2.5°
ω scan	h = −21→25
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −11→10
T_min = 0.737, T_max = 1.000	l = −20→20
11190 measured reflections

Refinement top

Refinement on F²	1 restraint
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.030	w = 1/[σ²(F_o²) + (0.0309P)² + 1.2812P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.073	(Δ/σ)_max = 0.001
S = 1.03	Δρ_max = 0.38 e Å⁻³
3095 reflections	Δρ_min = −0.35 e Å⁻³
155 parameters

Crystal data top

[Zn(C₆H₁₂NOS₂)₂(C₁₀H₈N₂)]	V = 2700.5 (3) Å³
M_r = 578.12	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 19.4997 (11) Å	µ = 1.25 mm⁻¹
b = 9.0027 (5) Å	T = 100 K
c = 15.5352 (8) Å	0.25 × 0.25 × 0.15 mm
β = 98.031 (5)°

Data collection top

Agilent SuperNova Dual diffractometer with Atlas detector	3095 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	2657 reflections with I > 2σ(I)
T_min = 0.737, T_max = 1.000	R_int = 0.048
11190 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	155 parameters
wR(F²) = 0.073	1 restraint
S = 1.03	Δρ_max = 0.38 e Å⁻³
3095 reflections	Δρ_min = −0.35 e Å⁻³

Special details top

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

	x	y	z	U_iso*/U_eq
Zn	0.5000	0.74113 (3)	0.7500	0.01278 (9)
S1	0.58946 (2)	0.56650 (5)	0.82428 (3)	0.01649 (12)
S2	0.58906 (2)	0.69208 (5)	0.65006 (3)	0.01671 (12)
O1	0.81368 (8)	0.48579 (17)	0.82921 (10)	0.0311 (4)
H1O	0.8403 (11)	0.416 (2)	0.8210 (17)	0.047*
N1	0.67544 (8)	0.47424 (17)	0.71467 (10)	0.0146 (3)
N2	0.46566 (8)	0.93220 (16)	0.67036 (10)	0.0138 (3)
C1	0.62467 (10)	0.56746 (19)	0.72861 (12)	0.0141 (4)
C2	0.70163 (10)	0.3630 (2)	0.78132 (12)	0.0193 (4)
H2A	0.7249	0.2822	0.7533	0.023*
H2B	0.6619	0.3191	0.8056	0.023*
C3	0.75234 (11)	0.4277 (2)	0.85548 (13)	0.0270 (5)
H3A	0.7288	0.5078	0.8837	0.032*
H3B	0.7651	0.3491	0.8994	0.032*
C4	0.69560 (10)	0.4583 (2)	0.62598 (12)	0.0182 (4)
H4	0.6837	0.5539	0.5946	0.022*
C5	0.65197 (11)	0.3372 (2)	0.57632 (13)	0.0256 (5)
H5A	0.6028	0.3617	0.5737	0.038*
H5B	0.6613	0.2419	0.6061	0.038*
H5C	0.6638	0.3301	0.5172	0.038*
C6	0.77272 (11)	0.4326 (3)	0.62649 (14)	0.0273 (5)
H6A	0.7989	0.5095	0.6617	0.041*
H6B	0.7836	0.4371	0.5668	0.041*
H6C	0.7854	0.3347	0.6513	0.041*
C7	0.43644 (10)	0.9239 (2)	0.58712 (12)	0.0169 (4)
H7	0.4245	0.8288	0.5631	0.020*
C8	0.42296 (10)	1.0474 (2)	0.53475 (12)	0.0208 (4)
H8	0.4014	1.0375	0.4763	0.025*
C9	0.44151 (11)	1.1856 (2)	0.56917 (13)	0.0242 (5)
H9	0.4330	1.2725	0.5346	0.029*
C10	0.47270 (11)	1.1956 (2)	0.65477 (13)	0.0212 (4)
H10	0.4863	1.2894	0.6795	0.025*
C11	0.48384 (10)	1.0669 (2)	0.70400 (11)	0.0151 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn	0.01357 (17)	0.01108 (16)	0.01328 (16)	0.000	0.00045 (12)	0.000
S1	0.0208 (3)	0.0152 (2)	0.0139 (2)	0.00390 (18)	0.00368 (19)	0.00164 (17)
S2	0.0166 (3)	0.0176 (3)	0.0158 (2)	0.00287 (19)	0.00185 (18)	0.00486 (18)
O1	0.0267 (9)	0.0260 (9)	0.0369 (9)	0.0060 (7)	−0.0081 (7)	−0.0051 (7)
N1	0.0148 (8)	0.0147 (8)	0.0139 (8)	0.0021 (6)	0.0006 (6)	−0.0012 (6)
N2	0.0136 (8)	0.0141 (8)	0.0135 (8)	−0.0003 (6)	0.0015 (6)	−0.0003 (6)
C1	0.0145 (10)	0.0128 (9)	0.0142 (9)	−0.0027 (7)	−0.0008 (7)	−0.0016 (7)
C2	0.0231 (11)	0.0150 (10)	0.0191 (10)	0.0072 (8)	0.0004 (8)	0.0017 (8)
C3	0.0301 (13)	0.0275 (12)	0.0208 (11)	0.0131 (9)	−0.0054 (9)	−0.0023 (9)
C4	0.0202 (10)	0.0195 (10)	0.0157 (10)	0.0018 (8)	0.0053 (8)	−0.0018 (7)
C5	0.0280 (12)	0.0292 (12)	0.0191 (10)	−0.0040 (9)	0.0020 (9)	−0.0073 (9)
C6	0.0200 (11)	0.0360 (13)	0.0266 (12)	0.0052 (9)	0.0051 (9)	−0.0051 (9)
C7	0.0150 (10)	0.0201 (10)	0.0152 (9)	−0.0009 (7)	0.0006 (7)	−0.0020 (7)
C8	0.0199 (11)	0.0300 (12)	0.0119 (9)	0.0049 (8)	0.0002 (8)	0.0041 (8)
C9	0.0296 (12)	0.0224 (11)	0.0211 (11)	0.0079 (9)	0.0058 (9)	0.0099 (8)
C10	0.0304 (12)	0.0127 (10)	0.0205 (10)	0.0032 (8)	0.0042 (9)	0.0015 (8)
C11	0.0166 (10)	0.0144 (9)	0.0149 (10)	0.0022 (7)	0.0041 (8)	−0.0007 (7)

Geometric parameters (Å, º) top

Zn—N2ⁱ	2.1695 (15)	C3—H3B	0.9900
Zn—N2	2.1695 (15)	C4—C6	1.521 (3)
Zn—S1	2.5068 (5)	C4—C5	1.525 (3)
Zn—S1ⁱ	2.5068 (5)	C4—H4	1.0000
Zn—S2ⁱ	2.5247 (5)	C5—H5A	0.9800
Zn—S2	2.5247 (5)	C5—H5B	0.9800
S1—C1	1.7221 (19)	C5—H5C	0.9800
S2—C1	1.7301 (18)	C6—H6A	0.9800
O1—C3	1.417 (3)	C6—H6B	0.9800
O1—H1O	0.833 (10)	C6—H6C	0.9800
N1—C1	1.338 (2)	C7—C8	1.381 (3)
N1—C2	1.479 (2)	C7—H7	0.9500
N1—C4	1.492 (2)	C8—C9	1.382 (3)
N2—C7	1.340 (2)	C8—H8	0.9500
N2—C11	1.348 (2)	C9—C10	1.386 (3)
C2—C3	1.525 (3)	C9—H9	0.9500
C2—H2A	0.9900	C10—C11	1.388 (3)
C2—H2B	0.9900	C10—H10	0.9500
C3—H3A	0.9900	C11—C11ⁱ	1.479 (4)

N2ⁱ—Zn—N2	75.08 (8)	O1—C3—H3B	108.7
N2ⁱ—Zn—S1	95.47 (4)	C2—C3—H3B	108.7
N2—Zn—S1	154.06 (4)	H3A—C3—H3B	107.6
N2ⁱ—Zn—S1ⁱ	154.07 (4)	N1—C4—C6	113.45 (16)
N2—Zn—S1ⁱ	95.47 (4)	N1—C4—C5	109.62 (16)
S1—Zn—S1ⁱ	102.32 (2)	C6—C4—C5	112.05 (17)
N2ⁱ—Zn—S2ⁱ	88.40 (4)	N1—C4—H4	107.1
N2—Zn—S2ⁱ	107.78 (4)	C6—C4—H4	107.1
S1—Zn—S2ⁱ	95.822 (17)	C5—C4—H4	107.1
S1ⁱ—Zn—S2ⁱ	71.289 (16)	C4—C5—H5A	109.5
N2ⁱ—Zn—S2	107.78 (4)	C4—C5—H5B	109.5
N2—Zn—S2	88.39 (4)	H5A—C5—H5B	109.5
S1—Zn—S2	71.288 (16)	C4—C5—H5C	109.5
S1ⁱ—Zn—S2	95.822 (17)	H5A—C5—H5C	109.5
S2ⁱ—Zn—S2	159.86 (3)	H5B—C5—H5C	109.5
C1—S1—Zn	86.29 (6)	C4—C6—H6A	109.5
C1—S2—Zn	85.55 (6)	C4—C6—H6B	109.5
C3—O1—H1O	109.6 (19)	H6A—C6—H6B	109.5
C1—N1—C2	120.14 (15)	C4—C6—H6C	109.5
C1—N1—C4	120.40 (15)	H6A—C6—H6C	109.5
C2—N1—C4	118.15 (14)	H6B—C6—H6C	109.5
C7—N2—C11	118.51 (16)	N2—C7—C8	122.95 (17)
C7—N2—Zn	124.18 (12)	N2—C7—H7	118.5
C11—N2—Zn	116.66 (12)	C8—C7—H7	118.5
N1—C1—S1	121.98 (14)	C7—C8—C9	118.59 (18)
N1—C1—S2	121.71 (14)	C7—C8—H8	120.7
S1—C1—S2	116.28 (11)	C9—C8—H8	120.7
N1—C2—C3	113.23 (16)	C8—C9—C10	119.06 (18)
N1—C2—H2A	108.9	C8—C9—H9	120.5
C3—C2—H2A	108.9	C10—C9—H9	120.5
N1—C2—H2B	108.9	C9—C10—C11	119.24 (18)
C3—C2—H2B	108.9	C9—C10—H10	120.4
H2A—C2—H2B	107.7	C11—C10—H10	120.4
O1—C3—C2	114.06 (17)	N2—C11—C10	121.63 (17)
O1—C3—H3A	108.7	N2—C11—C11ⁱ	115.33 (10)
C2—C3—H3A	108.7	C10—C11—C11ⁱ	123.03 (11)

C2—N1—C1—S1	1.8 (2)	C1—N1—C4—C5	−89.1 (2)
C4—N1—C1—S1	168.55 (13)	C2—N1—C4—C5	77.9 (2)
C2—N1—C1—S2	−176.25 (13)	C11—N2—C7—C8	−1.2 (3)
C4—N1—C1—S2	−9.5 (2)	Zn—N2—C7—C8	−171.67 (14)
Zn—S1—C1—N1	−170.98 (15)	N2—C7—C8—C9	1.2 (3)
Zn—S1—C1—S2	7.21 (9)	C7—C8—C9—C10	−0.2 (3)
Zn—S2—C1—N1	171.03 (15)	C8—C9—C10—C11	−0.7 (3)
Zn—S2—C1—S1	−7.16 (9)	C7—N2—C11—C10	0.3 (3)
C1—N1—C2—C3	−79.6 (2)	Zn—N2—C11—C10	171.46 (14)
C4—N1—C2—C3	113.39 (18)	C7—N2—C11—C11ⁱ	−179.62 (19)
N1—C2—C3—O1	−62.3 (2)	Zn—N2—C11—C11ⁱ	−8.5 (3)
C1—N1—C4—C6	144.80 (18)	C9—C10—C11—N2	0.7 (3)
C2—N1—C4—C6	−48.2 (2)	C9—C10—C11—C11ⁱ	−179.4 (2)

Symmetry code: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···S2ⁱⁱ	0.84 (2)	2.45 (2)	3.2437 (16)	160 (2)
C5—H5B···O1ⁱⁱ	0.98	2.54	3.512 (2)	175
C9—H9···S2ⁱⁱⁱ	0.95	2.86	3.550 (2)	130

Symmetry codes: (ii) −x+3/2, y−1/2, −z+3/2; (iii) −x+1, −y+2, −z+1.

Geometric data (Å, °) for (I), unsolvated (I) and for (II) top

Parameter	(I)^a	unsolvated (I)	(II)^b
Zn—S1	2.5361 (5)	2.4632 (12)	2.5068 (5)
Zn—S2	2.5163 (5)	2.5968 (13)	2.5247 (5)
Zn—S3	2.5361 (5)	2.5030 (12)	2.5068 (5)
Zn—S4	2.5163 (5)	2.6045 (13)	2.5247 (5)
Zn—N2	2.1682 (15)	2.157 (4)	2.1695 (15)
Zn—N3	2.1682 (15)	2.154 (3)	2.1695 (15)
C—S	1.7198 (18)–1.7253 (18)	1.696 (4)–1.726 (5)	1.7221 (19)–1.7301 (18)
S1—Zn—S2	71.376 (15)	70.46 (4)	71.289 (16)
S3—Zn—S4	71.376 (15)	70.15 (4)	71.289 (16)
N2—Zn—N2	75.71 (8)	74.72 (12)	75.08 (8)

Notes: (a) S3, S4 and N3 are S1ⁱ, S2ⁱ and N2ⁱ for (i) 3/2 - x, 1/2 - y, z; (b) S3, S4 and N3 are S1ⁱ, S2ⁱ and N2ⁱ for (i) 1 - x, y, 3/2 - z.

Hydrogen-bond geometry (Å, º) for (I) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O1	0.832 (15)	1.865 (16)	2.696 (2)	177 (3)
O1—H1O···O1W	0.83 (2)	1.88 (2)	2.7115 (19)	177 (2)
O1W—H1W···O2ⁱ	0.834 (16)	1.905 (18)	2.7216 (19)	166 (2)
O1W—H2W···S2ⁱⁱ	0.832 (18)	2.451 (18)	3.2733 (15)	169.9 (19)
C7—H7···O1Wⁱⁱⁱ	0.95	2.58	3.517 (2)	171
C6—H6···S2^iv	0.95	2.81	3.490 (2)	129
C9—H9···S1^v	0.95	2.84	3.6857 (18)	149

Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+1, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1/2, −y+1/2, z; (v) −x+3/2, y, z+1/2.

Hydrogen-bond geometry (Å, º) for (II) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···S2ⁱ	0.84 (2)	2.448 (19)	3.2437 (16)	160 (2)
C5—H5B···O1ⁱ	0.98	2.54	3.512 (2)	175
C9—H9···S2ⁱⁱ	0.95	2.86	3.550 (2)	130

Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) −x+1, −y+2, −z+1.

Experimental details

	(I)	(II)
Crystal data
Chemical formula	[Zn(C₅H₁₀NO₂S₂)₂(C₁₀H₈N₂)]·2H₂O	[Zn(C₆H₁₂NOS₂)₂(C₁₀H₈N₂)]
M_r	618.10	578.12
Crystal system, space group	Orthorhombic, Pccn	Monoclinic, C2/c
Temperature (K)	100	100
a, b, c (Å)	6.7730 (3), 23.1063 (11), 16.9483 (8)	19.4997 (11), 9.0027 (5), 15.5352 (8)
α, β, γ (°)	90, 90, 90	90, 98.031 (5), 90
V (Å³)	2652.4 (2)	2700.5 (3)
Z	4	4
Radiation type	Mo Kα	Mo Kα
µ (mm⁻¹)	1.28	1.25
Crystal size (mm)	0.40 × 0.30 × 0.20	0.25 × 0.25 × 0.15

Data collection
Diffractometer	Agilent SuperNova Dual diffractometer with an Atlas detector	Agilent SuperNova Dual diffractometer with Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2012)	Multi-scan (CrysAlis PRO; Agilent, 2012)
T_min, T_max	0.778, 1.000	0.737, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	21039, 3047, 2607	11190, 3095, 2657
R_int	0.049	0.048
(sin θ/λ)_max (Å⁻¹)	0.650	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.066, 1.02	0.030, 0.073, 1.03
No. of reflections	3047	3095
No. of parameters	171	155
No. of restraints	4	1
Δρ_max, Δρ_min (e Å⁻³)	0.39, −0.34	0.38, −0.35

Computer programs: CrysAlis PRO (Agilent, 2012), SHELXS97 (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015), ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).

Acknowledgements

The University of Malaya's Postgraduate Research Grant Scheme (No. PG097-2014B) is gratefully acknowledged.

References

Agilent (2012). CrysAlis PRO. Agilent Technologies Inc., Santa Clara, CA, USA. Google Scholar
Benson, R. E., Ellis, C. A., Lewis, C. E. & Tiekink, E. R. T. (2007). CrystEngComm, 9, 930–941. Web of Science CSD CrossRef CAS Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Broker, G. A. & Tiekink, E. R. T. (2011). Acta Cryst. E67, m320–m321. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Chen, D., Lai, C. S. & Tiekink, E. R. T. (2003). Z. Kristallogr. 218, 747–752. CAS Google Scholar
Cox, M. J. & Tiekink, E. R. T. (2009). Z. Kristallogr. 214, 184–190. Google Scholar
Decken, A., Gossage, R. A., Chan, M. Y., Lai, C. S. & Tiekink, E. R. T. (2004). Appl. Organomet. Chem. 18, 101–102. Web of Science CSD CrossRef CAS Google Scholar
Deng, Y.-H., Liu, J., Li, N., Yang, Y.-L. & Ma, H.-W. (2007). Acta Chim. Sin. 65, 2868–2874. CAS Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Heard, P. J. (2005). Prog. Inorg. Chem. 53, 1–69. Web of Science CrossRef CAS Google Scholar
Hogarth, G. (2005). Prog. Inorg. Chem. 53, 71–561. Web of Science CrossRef CAS Google Scholar
Howie, R. A., de Lima, G. M., Menezes, D. C., Wardell, J. L., Wardell, S. M. S. V., Young, D. J. & Tiekink, E. R. T. (2008). CrystEngComm, 10, 1626–1637. Web of Science CSD CrossRef CAS Google Scholar
Howie, R. A., Tiekink, E. R. T., Wardell, J. L. & Wardell, S. M. S. V. (2009). J. Chem. Crystallogr. 39, 293–298. CSD CrossRef CAS Google Scholar
Ishak, D. H. A., Ooi, K. K., Ang, K. P., Akim, A. Md., Cheah, Y. K., Nordin, N., Halim, S. N. B. A., Seng, H.-L. & Tiekink, E. R. T. (2014). J. Inorg. Biochem. 130, 38–51. Web of Science CrossRef CAS PubMed Google Scholar
Ivanov, A. V., Korneeva, E. V., Gerasimenko, A. V. & Forsling, W. (2005). Russ. J. Coord. Chem. 31, 695–707. CrossRef CAS Google Scholar
Jamaludin, N. S., Goh, Z.-J., Cheah, Y. K., Ang, K.-P., Sim, J. H., Khoo, C. H., Fairuz, Z. A., Halim, S. N. B. A., Ng, S. W., Seng, H.-L. & Tiekink, E. R. T. (2013). Eur. J. Med. Chem. 67, 127–141. Web of Science CSD CrossRef CAS PubMed Google Scholar
Masui, H. (2001). Coord. Chem. Rev. 219–221, 957–992. Web of Science CrossRef CAS Google Scholar
Poplaukhin, P., Arman, H. D. & Tiekink, E. R. T. (2012). Z. Kristallogr. 227, 363–368. CSD CrossRef CAS Google Scholar
Poplaukhin, P. & Tiekink, E. R. T. (2010). CrystEngComm, 12, 1302–1306. Web of Science CSD CrossRef Google Scholar
Safbri, S. A. M., Halim, S. N. A., Jotani, M. M. & Tiekink, E. R. T. (2016). Acta Cryst. E72 158–163. CSD CrossRef IUCr Journals 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
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tan, Y. S., Halim, S. N. A. & Tiekink, E. R. T. (2016). Z. Kristallogr. 231. doi: 10.1515/zkri-2015-1889. Google Scholar
Tan, Y. S., Ooi, K. K., Ang, K. P., Akim, A. Md., Cheah, Y.-K., Halim, S. N. A., Seng, H.-L. & Tiekink, E. R. T. (2015). J. Inorg. Biochem. 150, 48–62. CSD CrossRef CAS PubMed Google Scholar
Tan, Y. S., Sudlow, A. L., Molloy, K. C., Morishima, Y., Fujisawa, K., Jackson, W. J., Henderson, W., Halim, S. N., Ng, S. W. & Tiekink, E. R. T. (2013). Cryst. Growth Des. 13, 3046–3056. CSD CrossRef CAS Google Scholar
Tiekink, E. R. T. (2003). CrystEngComm, 5, 101–113. Web of Science CrossRef CAS Google Scholar
Tiekink, E. R. T. & Zukerman-Schpector, J. (2011). Chem. Commun. 47, 6623–6625. CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhong, Y., Zhang, W., Fan, J., Tan, M., Lai, C. S. & Tiekink, E. R. T. (2004). Acta Cryst. E60, m1633–m1635. CSD CrossRef IUCr Journals Google Scholar

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ISSN: 2056-9890

Volume 72| Part 2| February 2016| Pages 203-208

doi:10.1107/S2056989016000700

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