Crystal structure of μ3-tetrathioantimonato-tris[(cyclam)zinc(II)] tetrathioantimonate acetonitrile disolvate dihydrate showing Zn disorder over the cyclam ring planes (cyclam = 1,4,8,11-tetraazacyclotetradecane)

In the crystal structure of the title compound, [Zn(cyclam)]2+ cations and SbS4 3– anions are present, which are linked to acetonitrile and water solvate molecules via intermolecular hydrogen bonding.

Reaction of Zn(ClO 4 ) 2 Á6H 2 O with cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane, C 10 H 24 N 4 ) and Na 3 SbS 4 in an acetonitrile/water mixture led to the formation of crystals of the title compound, [Zn 3 (SbS 4 )(C 10 H 24 N 4 ) 3 ](SbS 4 )Á-2CH 3 CNÁ2H 2 O or [(Zn-cyclam) 3 (SbS 4 ) 2 ](H 2 O) 2 (acetonitrile) 2 . The set-up of the crystal structure is similar to that of [(Zn-cyclam) 3 (SbS 4 ) 2 ] . 8H 2 O reported recently [Danker et al. (2021). Dalton Trans. 50, 18107-18117]. The crystal structure of the title compound consists of three crystallographically independent Zn II cations (each disordered around centers of inversion), three centrosymmetric cyclam ligands, one SbS 4 3anion, one water and one acetonitrile molecule occupying general positions. The acetonitrile molecule is equally disordered over two sets of sites. Each Zn 2+ cation is bound to four nitrogen atoms of a cyclam ligand and one sulfur atom of the SbS 4 3anion within a distorted square-pyramidal coordination. The cation disorder of the [Zn(cyclam)] 2+ complexes is discussed in detail and is also observed in other compounds, where identical ligands are located above and below the [Zn(cyclam)] 2+ plane. In the title compound, the building units are arranged in layers parallel to the bc plane forming pores in which the acetonitrile solvate molecules are located. Intermolecular C-HÁ Á ÁS hydrogen bonding links these units to the SbS 4 3anions. Between the layers, additional water solvate molecules are present that act as acceptor and donor groups for intermolecular N-HÁ Á ÁO and O-HÁ Á ÁS hydrogen bonding.
For several years, we have been interested in the syntheses and structural behaviors of thioantimonate(V) compounds (Stä hler et al., 2001;Schur et al., 2001;Pienack et al., 2008). In the early stages of these studies, such compounds were prepared at elevated temperatures under solvothermal conditions but subsequently, new synthetic approaches using soluble precursors such as Na 3 SbS 4 Á9H 2 O were developed, which allowed the synthesis of new thioantimonates at room temperature (Anderer et al., 2016). The major advantage of this route is that, under these conditions, thioantimonate compounds containing Sb V atoms can be prepared selectively, which is otherwise difficult to achieve. In most cases, we used transition-metal complexes (TMCs) as counter-cations. In this context, cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) became of interest as a ligand. The formed complex cations are in a fourfold coordination environment and provide additional coordination sites for thioantimonate anions, which can lead to the formation of networks by (TMC)-S bonds to the anion. Following this synthetic approach, we reacted cyclam with Na 3 SbS 4 Á9H 2 O and different transition-metal salts, which led to the formation of compounds with compositions: [(Cu-cyclam) (Danker et al., 2021) and [(Co-cyclam) Nä ther et al., 2022). In the crystal structure of the cobalt and copper compounds, the metal cations are octahedrally coordinated by the four N atoms of the cyclam ligand and by two S atoms of the tetrathioantimonate(V) anions in trans-positions. Each of the SbS 4 3anions coordinates to three crystallographically independent [M(cyclam)] 2+ cations (M = Cu and Co), linking the cations and anions into layers. Within these layers, channels are formed in which water or acetonitrile solvate molecules are located. These layers are connected into a three-dimensional network by intermolecular hydrogen bonding via water molecules. In the case of M = Zn, a different coordination is observed, because this cation is shifted out of the N 4 plane of the cyclam ligand and because of the center of inversion is disordered over both ring planes (Danker et al., 2021). In this context, it is noted that such a disorder in Zn-cyclam complexes has already been observed in other, different compounds, but the structural consequences were not discussed in detail (see Database survey).
To find more examples of similar compounds, additional syntheses were performed. From an acetonitrile/water mixture, crystals of another Zn II -cyclam tetrathioantimonate(V) compound with composition [(Zn-cyclam) 3 -(SbS 4 ) 2 ](H 2 O) 2 (acetonitrile) 2 were obtained. Likewise, in this compound disorder of the Zn 2+ cations is observed and the structural consequences are discussed in this contribution.

Structural commentary
The asymmetric unit of the title compound consists of three half cyclam ligands (completed by inversion symmetry), one SbS 4 3anion, one water solvent molecule, one disordered acetonitrile solvent molecule and three Zn 2+ cations that are disordered around centers of inversion (Fig. 1). In contrast to [(Cu-cyclam)  Part of the crystal structure of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level. The hydrogen atoms were omitted for clarity; the disorder of the acetonitrile solvent molecule and the Zn 2+ cations is shown with full and open bonds. [Symmetry codes: (i) Àx + 1, Ày, Àz + 1; (ii) Àx + 1, Ày + 1, Àz; (iii) Àx, Ày + 1, Àz + 1.] fivefold coordination defined by the four N atoms of the cyclam ligand in the basal plane and one S atom of the SbS 4 3anions in the apical position (Fig. 2, Table 1). The Zn-S distances to the Zn 2+ cation on the other side of the N 4 plane are 3.2748 (8) Å (Zn1), 3.2063 (9) Å (Zn2) and 3.4234 (9) Å (Zn3), which are much too long for a significant interaction. Because all of the Zn 2+ cations are disordered around centers of inversion, the connectivity within the crystal structure is difficult to define. In principle, the SbS 4 3anions can coordinate to one, two or three [Zn(cyclam] 2+ cations (Fig. 3).
If the disorder were not present and the Zn 2+ cations were located on centers of inversion in the planes of the cyclam ligands, layers would be formed ( 3anions must be present for charge balance as well as for the correct ratio between Zncyclam cations and tetrathioantimonate anions (Fig. 4B). Alternatively, the anion can coordinate to two cations forming [(Zn-cyclam) 2 (SbS 4 )] + cations. Then, an equivalent amount of [(Zn-cyclam)(SbS 4 )] À anions must be present to have the correct ratio between Zn-cyclam and the tetrathioantimonate anions (Fig. 4C). The arrangement with [(Zn-cyclam) 3 (SbS 4 )] 3+ cations and an SbS 4 3anion appears to be more likely because of the higher charge, but this is in fact difficult to prove. This possibility can also not be verified from the Sb-S bond lengths because they are very similar for the thioantimonate anions, which is expected because they are averaged over the whole crystal structure (Table 1).
It is noted that such a cation disorder is also observed in other compounds containing [Zn(cyclam)] 2+ cations, which includes [(Zn-cyclam) 3 (SbS 4 ) 2 ]Á8H 2 O (Danker et al., 2021) and other compounds where identical anions are located above and below the N 4 plane of the [Zn(cyclam] 2+ cations (see Database survey). The reason for this disorder is still unclear. For [(Cu-cyclam) 3 (SbS 4 ) 2 ]Á20H 2 O and [(Zncyclam) 3 (SbS 4 ) 2 ]Á8H 2 O, DFT calculations were performed, which reasonably reproduced the octahedral coordination for the Cu 2+ and the square-pyramidal coordination for the Zn 2+ cations (Danker et al., 2021). Moreover, these calculations also revealed that in the Cu compound, the attractive dispersion interactions between the cyclam ligand and the SbS 4 3anion contribute to the environment of the metal cation, which might be the reason for the different behavior of the Cu 2+ and View of the coordination spheres of the three crystallographically independent Zn 2+ cations. The cation disorder is not shown for clarity    the Zn 2+ cations. Also, for very large cations it might be possible that they are shifted out of the center of the cyclam ring, because there is not enough space available within the ring plane. To examine whether the size of Zn 2+ might be a reason for the shift out of the N 4 plane, we analyzed the ionic radii (Shannon, 1976) and found no significant differences for octahedrally coordinated Zn 2+ (r = 0.74 Å ), Co 2+ hs (r = 0.745 Å ), Co 2+ ls (r = 0.65 Å ) and Cu 2+ (r = 0.73 Å ). One may argue that in [(Co-cyclam) 3 (SbS 4 ) 2 ](H 2 O) 2 (acetonitrile) 2 , for which the spin state is not known, Co 2+ is ordered because it adopts the low-spin state with a smaller ionic radius compared to the high-spin state. However, in [(Cu-cyclam) 3 (SbS 4 ) 2 ]Á-20H 2 O, no disorder is observed and the ionic radius of Cu 2+ is similar to that of Zn 2+ , and larger than for Co II ls . Hence, the ionic radius is most probably not the driving force of the disorder of Zn 2+ . We also checked many other transitionmetal cations in the form of their cyclam complexes, and there were no indications for metal disorder except in some of the Zn compounds, which suggests that such a disorder is limited to Zn 2+ cations. Even for these compounds, only about 10% show disorder (see Database survey). A possible explanation for these observations might be the ligand field stabilization energy, which is zero for Zn 2+ (electronic configuration 3d 10 ), while it is reasonably large for Co 2+ (3d 7 ) and Cu 2+ (3d 9 ), resulting in a preference of the position of these cations within the N 4 plane. Because not all [Zn(cyclam] 2+ complexes show disorder, secondary effects (sterical demands, packing) may also be responsible for the disorder.

Supramolecular features
The cations and anions are arranged into layers parallel to the bc plane in such a way that channels are formed in which the disordered acetonitrile solvate molecules are located. The latter are hydrogen-bonded to the tetrathioantimonate anions by intermolecular C-HÁ Á ÁS interactions (Figs. 4 and 5, Table 2). One of the C-HÁ Á ÁS angles is close to linearity, which indicates that this is a relatively strong interaction. The water molecules are located between the layers and are hydrogen-bonded to the tetrathioantimonate anions via comparatively strong intermolecular O-HÁ Á ÁS interactions ( Table 2). The water molecules also act as acceptors for strong N-HÁ Á ÁO hydrogen bonding involving the NH hydrogen atoms of the cyclam ligands (Fig. 5, Table 2). The NH groups are also hydrogen-bonded to the S atoms of the tetrathioantimonate(V) groups. There are additional C-HÁ Á ÁS interactions, but according to the the corresponding angles, it seems that these are only weak (Table 2).

Database survey
A search for structures of Zn 2+ -cyclam complexes in the Cambridge Structural Database (CSD version 5.42, last update November 2020; Groom et al., 2016) led to 34 hits but none of them contains SbS 4 3anions. However, as mentioned above, one compound with composition [(Zn-cyclam) 3 -(SbS 4 ) 2 ]Á8H 2 O has already been reported (Danker et al., 2021) but so far is not included in the database.
In one of the other structures, two [Zn(cyclam] 2+ cations are linked by oxalate anions into a centrosymmetric dimer, which means that both O atoms are on the same side of one cyclam ring (FIHYEB; Jo et al., 2005). In all remaining structures, the Zn 2+ cations seem to be sixfold coordinated with one monocoordinating donor atom at each side of the cyclam ring; however, for five of them no atomic coordinates are given (HEGNEM10, HEGNOW, HEGNOW10, VUSDUI20 and WARJAD). For these hits, it is difficult to decide whether disorder is present or not. In some of the entries, the Zn Crystal structure of the title compound in a view along the a axis with intermolecular hydrogen bonding shown as dashed lines. The disorder of the acetonitrile molecules is omitted for clarity, whereas that of each Zn 2+ cation is indicated. Symmetry codes: (i) Àx þ 1; Ày; Àz þ 1; (ii) Àx þ 1; Ày þ 1; Àz; (iii) Àx; Ày þ 1; Àz þ 1; (iv) x; y À 1; z; (v) Àx; Ày þ 1; Àz; (vi) Àx þ 1; Ày þ 1; Àz þ 1. disorder is mentioned in the database and this includes structures with the following refcodes: CUZHUA (Kato & Ito, 1985), in which the Zn 2+ cations are coordinated by methylcarbonato anions from both sites, DITZIP (Ito et al., 1984), in which the cations are linked to two thiocyanate anions and HEGNEM, HEGNOW and VUSDUI10 (Porai-Koshits et al., 1994), in which chloride, bromide and iodine anions are located on each side of the cyclam ligand. It should be noted that, for the first structure determination of ZnCl 2 (cyclam) (VUSDUI; Antsyshkina et al., 1991), no disorder is mentioned. One can assume that the disorder was overlooked and the Zn 2+ cation forced to be situated at the center of inversion. For the remaining structures, the two Zn-X bond lengths (X = O, Cl, Br, I) are identical in each case, which points to ordered structures. Nonetheless, in some cases the Zn 2+ cations are located on special positions and because no anisotropic displacement parameters are available in the corresponding CIFs, one cannot decide whether there are hints of disorder.

Synthesis of Na 3 SbS 4 Á9H 2 O (Schlippe's salt)
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 333 K for 1h and 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. The reaction mixture was then heated to 343 K for 6 h, filtered off and the filtrate was stored overnight at room temperature. Light-yellow-colored crystals formed overnight, were filtered off, washed with small amounts of water and dried in vacuo.

Synthesis of tris(cyclam-zinc(II)-bis-tetrathioantimonate)bis water-bis-acetonitrile solvate
Single crystals of the title compound were serendipitously obtained by dissolving 10 mg (0.274 mmol) of Zn(ClO 4 ) 2 Á6H 2 O (purchased from Alfa Aesar) and 10 mg (0.05 mmol) of cyclam (purchased from Strem Chemicals) in 2 ml of acetonitrile (purchased from Merck) to which 20 mg (0.14 mmol) of Na 3 SbS 4 Á9H 2 O dissolved in 1 ml of water were added. After storing this mixture for 3d at room temperature, a few colorless crystals of the title compound were obtained.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The C-H and N-H hydrogen atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined with U iso (H) =1.2U eq (C,N) (1.5 for methyl H atoms) using a riding model. The water hydrogen atoms were located in a difference-Fourier map, and their bond lengths set to ideal values with U iso (H) = 1.5U eq (O) using a riding model. The acetontrile molecule was modeled as being equally disordered over two sets of sites and was refined using a split model with restraints for the geometry and the components of the anisotropic displacement parameters. Each of the three Zn 2+ cations was found to be disordered around a center of inversion and thus was refined with half occupancy.
The crystal structure was alternatively refined in space group P1 but the disorder remained the same. There were also no hints of superstructure reflections, and in the diffraction pattern diffuse scattering was not observed.   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.