Synthesis and crystal structure of poly[[di-μ3-tetrathioantimonato-tris[(cyclam)cobalt(II)]] acetonitrile disolvate dihydrate] (cyclam = 1,4,8,11-tetraazacyclotetradecane)

In the crystal structure of the title compound, the [SbS4]3− anions are linked by the Co(cyclam) complex cations into rings, which are further connected into layers that are linked by intermolecular hydrogen bonding via the water solvate molecules and are arranged in such a way that cavities are formed, in which the disordered acetonitrile solvate molecules are located.

Reaction of Co(ClO 4 ) 2 Á6H 2 O with cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) and Na 3 SbS 4 Á9H 2 O (Schlippesches salt) in a mixture of acetonitrile and water leads to the formation of crystals of the title compound with the composition {[Co 3 (SbS 4 ) 2 (C 10 H 24 N 4 ) 3 ]Á2CH 3 CNÁ2H 2 O} n or {[(Co-cyclam) 3 -(SbS 4 ) 2 ]Á2(acetonitrile)Á2H 2 O} n . The crystal structure of the title compound consists of three crystallographically independent [Co-cyclam] 2+ cations, which are located on centers of inversion, one [SbS 4 ] 3À anion, one water and one acetonitrile molecule that occupy general positions. The acetonitrile molecule is disordered over two orientations and was refined using a split model. The Co II cations are coordinated by four N atoms of the cyclam ligand and two trans-S atoms of the tetrathioantimonate anion within slightly distorted octahedra. The unique [SbS 4 ] 3À anion is coordinated to all three crystallographically independent Co II cations and this unit, with its symmetry-related counterparts, forms rings composed of six Co-cyclam cations and six tetrathioantimonate anions that are further condensed into layers. These layers are perfectly stacked onto each other so that channels are formed in which acetontrile solvate molecules that are hydrogen bonded to the anions are embedded. The water solvate molecules are located between the layers and are connected to the cyclam ligands and the [SbS 4 ] 3À anions via intermolecular N-HÁ Á ÁO and O-HÁ Á ÁS hydrogen bonding.

Chemical context
Inorganic-organic chalcogenidometallates are an important class of compounds and many such compounds have been reported in the literature (Sheldrick & Wachhold, 1988;Bensch et al., 1997;Dehnen & Melullis, 2007;Wang et al., 2016;Zhou, 2016;Zhu & Dai, 2017;Nie et al., 2017). A large part of this family of compounds consists of thioantimonates, which exhibit a variety of coordination numbers that can lead to networks of different dimensionality (Jia et al., 2004;Powell et al., 2005;Spetzler et al., 2004;Zhang et al., 2007;Liu & Zhou, 2011;Engelke et al., 2004;Puls et al., 2006). Moreover, some of them have potential for applications, for example in the field of superionic conductors (Zhou et al., 2019) or as photoconductive materials (Pienack et al., 2008a). For these reasons, we have explored such compounds over many years (Schaefer et al., 2003;Stä hler et al., 2001;Schur et al., 1998Schur et al., , 2001Kiebach et al., 2004;Spetzler et al., 2004;Lü hmann et al., 2008;Pienack et al., 2008b). In the beginning, we synthesized new thioantimonates using elemental antimony, sulfur and amine molecules under solvothermal conditions but later we found that ISSN 2056-9890 many of these compounds are also available under solvothermal conditions if Schlippesches salt (Na 3 SbS 4 Á9H 2 O) or NaSbS 3 are used as reactants (Anderer et al., 2014(Anderer et al., , 2016Danker et al., 2020) (Rammelsberg, 1841;Long & Bowen, 1970;Mosselmanns et al., 2000;Planer-Friedrich & Scheinost, 2011;Planer-Friedrich & Wilson, 2012;Anderer et al., 2014). In addition, a variety of complex redox and condensation reactions occur, generating polymeric thioantimonate(III) anions, which are found in the structures of the reaction products. To prevent the reduction of Sb V to Sb III , a different synthesis strategy is required and the reaction temperature must be reduced to slow down the decomposition of Schlippesches salt. Using an aqueous solution of Na 3 SbS 4 Á9H 2 O and adding a solution of late transition-metal cations leads to immediate precipitation of sulfides or hydroxides, even when chelating amine molecules are added. To solve the problem we developed a two-solution strategy: an organic solution contains the transition-metal cations and the chelating amine molecule and a second solution comprises Schlippesches salt. In the organic solution, the transitionmetal complex is already generated in situ and mixing the two solutions leads to nucleation and successive growth of the product. A challenge is the integration of transition-metal cations into a thioantimonate(V) network, despite the [SbS 4 ] 3À anion offering four possible binding sites. In the course of this project we became interested in cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane), which is a tetradentate ligand. This means that in an octahedral coordination of a transition-metal cation, two coordination sites are provided to which thioantimonate(V) anions can coordinate, which, depending on the nature of the anion, can lead to the formation of the desired thioantimonate(V) networks.
In this context, we have reported on two new polymeric thioantimonates with the composition [(Cu-cyclam) 3 (SbS 4 ) 2 ]Á-20H 2 O and [(Zn-cyclam) 3 (SbS 4 ) 2 ]Á8H 2 O (Danker et al., 2021). In the crystal structure of the Cu compound, the copper cations are sixfold coordinated by the four N atoms of the cyclam ligand and two trans-sulfur atoms of the [SbS 4 ] 3À anions within slightly distorted octahedra. The copper cations are linked by the anions into rings by corner-sharing SbS 4 and CuN 4 S 2 units, which are condensed into layers. These layers are stacked in such a way that large pores are formed. Between the layers, water molecules are embedded. At first glance, the arrangement of the building blocks in the crystal structure of the Zn compound looks similar, but in this case the Zn II cation is disordered above and below the N 4 plane in a 1:1 ratio, which means that it is in a fivefold coordination of the four N atoms of the cyclam ligand and one S atom of the [SbS 4 ] 3À anions in a square-pyramidal geometry. The structural difference between the Cu and Zn coordinations was reproduced by DFT calculations (Danker et al., 2021). In the course of our systematic work we tried to prepare a similar compound with cobalt using the same synthetic approach. This led to crystals of the title compound, which were characterized by single-crystal X-ray diffraction.

Structural commentary
The asymmetric unit of the title compound consists of three crystallographically independent Co II cations and three independent cyclam ligands that are located on centers of inversion, as well as one [SbS 4 ] 3À anion, one water and one acetonitrile molecule that occupy general positions (Fig. 1). The acetonitrile molecule is disordered over two orientations and was refined using a split model (see Refinement). The Co II cations are six-coordinate being bound to the four N atoms of cyclam ligand that are located in the equatorial plane and two trans-S atoms of two inversion-related tetrathioantimonate anions that occupy the apical positions (Fig. 2). The Co-N bond lengths are very similar for the three crystallographically independent Co II cations whereas significant differences are found for the Co-S bond lengths (Table 1). These changes, however, do not correlate with the Sb-S distances ( Table 1). The angles around the Co centers prove that the octahedra are slightly distorted (see supporting information). The cyclam ligands are in the trans-III(S,S,R,R) configuration, which is the research communications most stable arrangement for the first row transition-metal cation-centered cyclam complexes (Bosnich et al., 1965).
The Sb-S bond lengths in the tetrathioantimonate anion (Table 1) are comparable and correspond to those observed in other compounds with this anion. From the S-Sb-S bond angles it is obvious that the tetrahedron is only slightly distorted (see supporting information). The [SbS 4 ] 3À anion shows the rare tridentate coordination mode and is linked to each of the three crystallographically independent Co II cations and with inversion-related counterparts, forming rings composed of six [SbS 4 ] 3À anions and six [Co(cyclam] 2+ cations (Fig. 3). These rings are condensed into layers parallel to the bc plane (Fig. 4)

Figure 3
Crystal structure of the title compound with a view of an 24-membered ring composed of six Co cations and six [SbS 4 ] 3À anions.

Figure 4
Crystal structure of the title compound with a view of the Co 3 (SbS 4 ) 2 network along the crystallographic a axis. The cyclam ligands are not shown for clarity.

Figure 2
Crystal structure of the title compound with a view of the coordination sphere of the three crystallographically independent Co cations.

Supramolecular features
Within the channels are embedded acetonitrile solvate molecules that are disordered and hydrogen bonded to the tetrathioantimonate anion (Fig. 5). The C-HÁ Á ÁS angles are close to linear, indicating that this is a significant interaction (Table 2). Water molecules are located between the layers and are connected to the [SbS 4 ] 3À anions via intermolecular O-HÁ Á ÁS hydrogen bonding, which is classed as strong because the angles are close to linearity and relatively short HÁ Á ÁS distances are observed (Table 2). These water molecules also act as acceptors for N-HÁ Á ÁO hydrogen bonding to the cyclam ligands (

Synthesis and crystallization
Synthesis of Na 3 SbS 4 Á9H 2 O Na 3 SbS 4 Á9H 2 O was synthesized by adding 16.6 g (0.213 mol) of Na 2 SÁxH 2 O (technical grade, purchased from Acros Organics) to 58 mL of demineralized water. This solution was heated to 323 K for 1 h. Afterwards, 19.6 g (0.058 mol) of Sb 2 S 3 (98%, purchased from Alfa Aesar) and 3.69 g (0.115 mol) of sulfur (min. 99%, purchased from Alfa Aesar) were added and the reaction mixture was heated to 343 K for 6 h. The reaction mixture was filtered and the filtrate was stored overnight, leading to the formation of slightly yellow crystals, which were filtered off, washed with small amounts of water and dried under vacuum (yield about 30% based on Sb 2 S 3 ).
Synthesis of the title compound 16 mg (0.044 mmol) of Co(ClO 4 ) 2 Á6H 2 O (purchased from Alfa Aesar) and 16 mg (0.08 mmol) of cyclam (purchased from Strem Chemicals) were dissolved in 2 mL of acetonitrile (purchased from Merck). To this solution, a solution of 50 mg (0.14 mmol) of Na 3 SbS 4 Á9H 2 O dissolved in 1 mL of H 2 O was added. Within 3d a few colorless crystals of the title compound were obtained, which were always contaminated with an additional and unknown phase that is amorphous to X-rays. This additional phase is also present if the reaction conditions are varied slightly. Therefore, one of the colorless crystals was selected for structure determination.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. All non-hydrogen atoms were refined anisotropically. The C-and N-bound H atoms were Crystal structure of the title compound with a view in the a-axis direction with intermolecular hydrogen bonding shown as dashed lines. The disorder of the acetonitrile molecules is omitted for clarity. Symmetry codes: (i) Àx þ 1; Ày; Àz þ 2; (ii) Àx þ 2; Ày; Àz þ 2; (iii) Àx þ 1; Ày; Àz þ 1; (iv) Àx þ 1; Ày þ 1; Àz þ 1; (v) Àx þ 2; Ày; Àz þ 1. located in the difference map but were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropically with U iso (H) = 1.2U eq (C,N) (1.5 for methyl H atoms) using a riding model. The O-bound H atoms were located in the difference map, their bond lengths were set to ideal values and finally they were refined isotropically with U iso (H) = 1.5U eq (O) using a riding model. The acetontrile molecule is disordered over two orientations and was refined using a split model (ratio: 1:1) with restraints for the geometry and the components of the anisotropic displacement parameters.  program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

Poly[[di-µ 3 -tetrathioantimonato-tris[(cyclam)cobalt(II)]] acetonitrile disolvate dihydrate]
Crystal data  (11) Special details 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.