Diammonium tetra­kis­(iso­thio­cyanato)­zincate–1,4,10,13,16-hexa­oxa­cyclo­octa­deca­ne–water (1/2/1)

K Showrilu; K Rajarajan; M NizamMohideen

doi:10.1107/S1600536813019739

. 2013 Jul 24;69(Pt 8):m469–m470. doi: 10.1107/S1600536813019739

Diammonium tetrakis(isothiocyanato)zincate–1,4,10,13,16-hexaoxacyclooctadecane–water (1/2/1)

K Showrilu ^a, K Rajarajan ^b,^*, M NizamMohideen ^c,^*

PMCID: PMC3793699 PMID: 24109286

Abstract

The title compound, (NH₄)₂[Zn(NCS)₄]·2C₁₂H₂₄O₆·H₂O, the result of the reaction of ammonium thiocyanate, 18-crown-6 and zinc(II) chloride in aqueous solution, exhibits an unusual supramolecular structure. The Zn atom, two of the thiocyanate chains and a water molecule, disordered over two positions, lie on a mirror plane. The macrocycle adopts a conformation with approximate D _3d symmetry. The ammonium molecules are contained within the bowl of the macrocycle via extensive N—H⋯O hydrogen bonds and the complex molecules are linked via N—H⋯S hydrogen bonds, forming chains along the c-axis direction. The macrocycle is disordered over two positions [refined occupancy ratio = 0.666 (8):0.334 (8)]. The S atoms of two isothiocyanate ligands are disordered within and about the mirror plane.

Related literature

For background to crown ether/ammonium ion complexes, see: Fender et al. (2002 ▶); Kryatova et al. (2004 ▶); Akutagawa et al. (2002 ▶); Ramesh et al. (2012 ▶). graphic file with name e-69-0m469-scheme1.jpg

Experimental

Crystal data

(NH₄)₂[Zn(NCS)₄]·2C₁₂H₂₄O₆·H₂O
M _r = 880.41
Orthorhombic,
a = 22.7875 (12) Å
b = 23.6254 (12) Å
c = 8.5593 (5) Å
V = 4608.0 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.77 mm⁻¹
T = 293 K
0.30 × 0.25 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.802, T _max = 0.861
24101 measured reflections
4641 independent reflections
2467 reflections with I > 2σ(I)
R _int = 0.058

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.175
S = 1.00
4641 reflections
454 parameters
276 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.72 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536813019739/su2617sup1.cif

e-69-0m469-sup1.cif^{(43.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813019739/su2617Isup2.hkl

e-69-0m469-Isup2.hkl^{(222.8KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4H⋯O1	0.88 (1)	2.44 (4)	3.069 (8)	129 (4)
N4—H4E⋯O2	0.87 (1)	2.06 (1)	2.934 (8)	176 (5)
N4—H4G⋯O4	0.88 (1)	1.97 (2)	2.829 (7)	166 (4)
N4—H4G⋯O5	0.88 (1)	2.53 (4)	3.010 (8)	115 (3)
N4—H4H⋯O6	0.88 (1)	2.05 (3)	2.850 (8)	150 (5)
N4—H4F⋯S1ⁱ	0.87 (1)	2.63 (2)	3.441 (4)	156 (4)

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

The authors are thankful to the SAIF, IIT Madras, for the data collection. KR thanks the University Grants Commission, Government of India, for financial support granted under a Major Research Project [F. No.41–1008/2012 (SR)].

supplementary crystallographic information

Comment

There is currently significant interest in crown ethers because of their ability to form non-covalent, hydrogen bonding complexes with ammonium cations both in the solid state and in solution (Fender et al., 2002; Kryatova et al., 2004; Akutagawa et al., 2002). Recently, the crystal structure of catena-Poly[ammonium(cadmium-tri-lthiocyanato κ⁴S:N; κ²N:S) -1,4,10,13,16- hexaoxacyclooctadecane (1/1)] (I), obtained in our laboratory, has been reported (Ramesh et al., 2012). In continuation of our studies of compounds containing 18-crown-6 macrocycles and ammonium cations NH₄⁺, we describe herein the crystal structure of the title compound (II), which is isostructural with (I).

The reaction of ammonium thiocyanate, 18-crown-6 and Zinc (II) chloride in aqueous solution yields the title compound, Fig. 1. All bond lengths and angles are normal and correspond to those reported for (I) (Ramesh et al., 2012). The C—S [average value of 1.658 (2) Å] and C—N [average value of 1.116 (2) Å] bond lengths indicate the presence of double-bond character. The zinc atom, Zn1, two of the thiocyanate chains [N2—C2—S2 and N3—C3—S3; symmetry code: x, -y + 1/2, z] and the water molecule lie in a mirror plane, except one of the disordered component sulfur atoms, which is inclined at quite an angle to the ac plane. The thiocyanate (N1—C1—S1 = 178.2 (4) °) ligands are almost linear.

The macrocycle adopts a conformation with approximate D_3d symmetry, with all O—C—C—O torsion angles being gauche and alternating in sign, and all C—O—C—C torsion angles being anti.

The sulfur atoms (S2 and S3) of the thiocyanate chains are disordered with large displacement parameters for the S atoms and short C—S bond lengths. The disorder over two positions was modelled and the site occupancies refined to 0.39 (9) and 0.61 (9) for atom S2 and 0.376 (9) and 0.248 (18) for atom S3. The entire crown either molecule is disordered, as detectable from the large displacement parameters for C and O atoms and short C—C and C—O bond lengths. The disorder over two positions was modelled and the site occupancies refined to 0.666 (9) and 0.334 (9) for carbon and oxygen atoms. The water molecule is disordered, as detectable from the large displacement parameters for the O atoms. The disorder over two positions was modelled and the site occupancies refined to 0.425 (15) and 0.575 (15). for carbon and oxygen atoms. The geometry was regularized by soft restraints.

The ammonium cations are contained within the bowl of the macrocycle via extensive N—H···O hydrogen bonding. The N—H···O [2.830 (7) to 3.074 (7) Å] and N—H···S [3.442 (4) Å] hydrogen bond lengths are within the usual range (Table 1 and Fig. 2).

In the crystal, the complex molecules are linked via N—H···S hydrogen bonds forming chains along the c axis (Table 1 and Fig. 2).

Experimental

A mixture of 18-crown-6, ammonium thiocyanate and Zinc (II) chloride were dissolved in an aqueous solution in the molar ratio 2:4:1 and thoroughly mixed for two hours to obtain a homogeneous mixture. The solution was allowed to evaporate slowly at ambient temperature. Colourless single crystals suitable for single-crystal X-ray diffraction analysis were obtained in a week.