Structural characterization of tetrakis(1,3-diazinane-2-thione)cadmium(II) sulfate

Abstract

A cadmium(II) complex tetrakis(1,3-diazinane-2-thione)cadmium(II) sulfate [Cd(Diaz) 4 ]SO 4 (1) is prepared and its crystal structure is determined by X-ray crystallography. The crystal structure of 1 consists of [Cd(Diaz) 4 ] 2+ and 2 4 SO − ions. In the complex ion, the central cadmium atom is coordinated by four Diaz molecules through sulfur atoms adopting a distorted tetrahedral geometry. The molecular structure is stabilized by N-H…O and N-H…S hydrogen bonding interactions. The complex is also characterized by IR and NMR spectroscopy and the spectroscopic data are discussed in terms of the nature of bonding.In recent years, considerable research efforts have been devoted to the structural characterization of cadmium(II) complexes of thioamides [1-22] because of their applications in biological systems [23,24], in analytical chemistry [25,26], in environmental toxicology [27], and as precursors for the preparation of CdS nanoparticles [28][29][30]. These structural reports describe that in most of the cases, cadmium(II) complexes exist as neutral monomeric [3][4][5][6][7][8][9][10][11][12][13][14][15][16] or polymeric [17][18][19] molecules of the general formula [CdL 2 X 2 ] with the cadmium atom possessing a tetrahedral or distorted octahedral coordination environment respectively. In some cases, ionic complexes of the type [CdL 4 ]X 2 (X = nitrate or sulfonate) are also formed [21, 22]. Recently, we have reported the crystal structures of two new complexes [Cd(Detu) 4 (SO 4 )] (Detu = N,N′diethylthiourea) [1] and [Cd(Diaz) 2 (CH 3 COO) 2 ] (Diaz = 1,3-diazinane-2-thione) [2] in which cadmium(II) shows severe distortions from the octahedral geometry. In view of our continued interest in the structural chemistry of cadmium(II) complexes with thiones [1-10], we report here the synthesis and crystal structure of a cadmium(II) complex of the heterocyclic ligand 1,3-diazinane-2-thione (3,4,5,6-tetrahydropyrimidine) [Cd(Diaz) 4 ]SO 4 . Experimental. Materials. Cadmium sulfate (CdSO 4 ⋅8/3H 2 O) was obtained from Merck Chemical Company, Germany. Diazinane-2-thione (Diaz) was prepared according to the procedure published in the literature [31].Synthesis of [Cd(Diaz) 4 ]SO 4 (1). The title complex was prepared by adding 0.24 g (2.0 mmol) of Diaz in 15 ml of methanol to an aqueous solution (5 ml) of cadmium sulfate (1.0 mmol, 0.26 g) and stirring the mixture for 30 min. The very light yellow cloudy solution was filtered and the filtrate was kept at room temperature for crystallization. As a result, the offwhite crystalline product was obtained, which was washed with methanol and dried.

Crystal structure of dichloridobis(1,3-diazinane-2-thione-κS)cadmium

“…The Cl-Cd-Cl bond angle is significantly smaller than the other bond angles, which could be due to the involvement of Cl in intramolecular (N-HÁ Á ÁCl) hydrogen bonding. The Cd-S and Cd-Cl bond lengths are in agreement with those reported for related compounds (Ahmad et al, 2011(Ahmad et al, , 2012Al-Arfaj et al, 1998;Bell et al, 2004;Lobana et al, 2008;Malik et al, 2010;Mahmood et al, 2012Mahmood et al, , 2015Wazeer et al, 2007). The two Diaz six-membered rings adopt half-chair conformations.…”

“…Therefore, complexes of cadmium with thiones are important as structural models to understand metal-sulfur interactions in biological systems (Akrivos, 2001;Bell et al, 2004). In view of this, the crystal structures of several cadmium complexes of thiones, such as imidazolidine-2-thione (Imt) and 1,3-diazinane-2-thione (Diaz), have been reported (Ahmad et al, 2012;Al-Arfaj et al, 1998;Bell et al, 2004;Lobana et al, 2008;Malik et al, 2010;Mahmood et al, 2012Mahmood et al, , 2015Wazeer et al, 2007). The complexity of structures of the L 2 CdX 2 type (where L is a thione and X is a halide or pseudohalide) ranges from mononuclear tetrahedral complexes to polymeric octahedral species.…”

“…The complexity of structures of the L 2 CdX 2 type (where L is a thione and X is a halide or pseudohalide) ranges from mononuclear tetrahedral complexes to polymeric octahedral species. We have reported recently the crystal structures of three cadmium complexes of Diaz, namely, [CdI 2 (Diaz) 2 ], [Cd(CH 3 COO) 2 (Diaz) 2 ] and [Cd(Diaz) 4 ]SO 4 (Ahmad et al, 2012;Mahmood et al, 2012Mahmood et al, , 2015. To learn more about the structural aspects of cadmium complexes, we report here the crystal structure of a cadmium chloride complex of 1,3-diazinane-2-thione, i.e.…”

2D polymeric cadmium(II) complexes containing 1,3-imidazolidine-2-thione (Imt) ligand, [Cd(Imt)(H 2 O) 2 (SO 4 )] n and [Cd(Imt) 2 (N 3 ) 2 ] n

“…The complexes with a Cd:thione ratio of 1:4 may be ionic or nonionic. In the ionic complexes like [Cd(2-mercaptopyridine) 4 ](NO 3 ) 2 [32] or [Cd(Diaz) 4 ]SO 4 (Diaz = 1,3-diazinane-2-thione) [33], the Cd(II) ion possesses a tetrahedral environment. The molecular species for instance, [Cd(Diaz) 4 Cl 2 ] [34] display a distorted octahedral geometry around the metal ion [29,34,35].…”

“…These structural studies show that thioureas or thiones coordinate to cadmium(II) via the sulfur atom. We have reported earlier the crystal structures of several cadmium(II) complexes of heterocyclic thiones [4,[5][6][7][8][9][10][14][15][16][17]23,24,[33][34][35]. To investigate further about the structural aspects of such complexes, we report in this work the spectroscopic data and the X-ray structures of two new 2D polymeric (2).…”