Synthesis and crystal structure of catena-poly[[bis[(2,2′;6′,2′′-terpyridine)manganese(II)]-μ4-pentathiodiantimonato] tetrahydrate] showing a 1D MnSbS network

In the crystal structure of the title compound, two [Sb2S5 [anions built up of two SbS3 units sharing common corners with each linked by two [Mn(terpyridine)]2+ cations into chains that are further linked into a 3D network by intermolecular O—H⋯O and O—H⋯S hydrogen bonding.


Chemical context
Inorganic-organic chalcogenidometallates are an important class of compounds that have been systematically investigated for several decades (Sheldrick & Wachhold, 1998;Dehnen & Melullis, 2007;Zhou et al., 2009;Seidlhofer et al., 2010;Wang et al., 2016;Zhou, 2016;Zhu & Dai, 2017). Therefore, a variety of compounds have been reported and some of them have potential for applications in different fields (Seidlhofer et al., 2011;Nie et al., 2014Nie et al., , 2016Nie et al., , 2017Yue et al.;. In this context, thioantimonates and thioselenates are of special interest because they consist of primary building units that show a variety of coordination numbers, which can be traced back to the lone electron pair of antimony (Bensch et al., 1997;Spetzler et al., 2004;Lü hmann et al., 2008). These primary building units can be further linked into discrete anions or networks of different dimensionality (Jia et al., 2004;Powell et al., 2005;Zhang et al., 2007;Liu & Zhou, 2011). This is the main reason why we have been interested in this class of compounds for many years.
In the course of these investigations we have prepared compounds with the general composition Mn 2 LSb 2 S 5 or Mn 2 L 2 Sb 2 S 5 with L as an mono-coordinating or a bis-chelating amine ligand such as, for example, methylamine, ethylamine, ethylenediamine or 1,3-diaminopropane (Bensch & Schur, 1996;Schur & Bensch, 2002;Schur et al., 2001). All of these compounds consist of SbS 3 pyramids as primary building units as well as MnS 6 and MnS 4 N 2 distorted octahedra. These units are linked to form Mn 2 Sb 2 S 4 hetero-cubane-like units that share common corners, edges and faces with a neighbouring heterocubane unit. These secondary building units are interconnected into layers. Within the MnSbS network, the SbS 3 pyramids are linked via common edges into chains. Thus, no discrete [Sb 2 S 5 ] 4À anions are present. The N atoms of the amine ligands in these compounds are coordinated to the Mn II ions and are always in the cis-position, thus arranged to form extended networks via Mn-S bond formation. Similar compounds have also been reported with 1,3-diaminopentane, diethylenetriamine and N-methyl-1,3-diaminopropane as ligands (Puls et al., 2006;Engelke et al., 2004). It is noted that diethylenetriamine acts as a bis-chelating ligand, because the central N atom is not involved in the Mn coordination.
To reduce the dimensionality of the MnSbS network that might allow access to discrete [Sb 2 S 5 ] 4À anions, we used the tetradentate ligand tris(2-aminoethyl)amine for the synthesis of such MnSbS compounds. In this case, a compound with the composition Mn 2 (tris(2-aminoethyl)amine) 2 Sb 2 S 5 was obtained, in which all four N atoms of the amine ligand are involved in the Mn coordination (Schaefer et al., 2004). In this case, only two of the six coordination sites of the Mn II cations are accessible for Mn-S bond formation. This compound consists of discrete [Sb 2 S 5 ] 4À anions, in which two SbS 3 pyramids are joined together via a common sulfur atom, which is in contrast to the compound mentioned above, where the SbS 3 units are linked by common sulfur edges into chains. These anions are connected to two [Mn(tris(2-aminoethyl)amine)] 2+ cations via the cis-coordinating terminal S atoms, forming discrete units instead of the condensed networks with monocoordinating or bis-chelating ligands.

Structural commentary
Mn II ion is fivefold coordinated by the three N atoms of the terpyridine ligand and two S atoms of two [Sb 2 S 5 ] 4À anions that are related by symmetry (Fig. 2). The Mn-N and Mn-S distances are very similar for both independent Mn II ions and correspond to literature values (Table 1). The Mn coordination environment is highly distorted with the three N atoms of the neutral terpyridine ligand and the Mn II ion in the same plane and the two S atoms above and below this plane, leading to an irregular coordination ( Fig. 1 and Table 1). The [Sb 2 S 5 ] 4À anion consists of two trigonal-pyramidal SbS 3 units that are linked by common corners (Fig. 3: top). The Sb-S bond lengths to the bridging S atom S3 are significantly longer than that to the terminal S atoms (

Supramolecular features
In the crystal of the title compound, the MnSbS chains are linked to the solvent water molecules by strong intermolecular O-HÁ Á ÁS hydrogen bonds ( Fig. 4 and Table 2). The water molecules of neighbouring chains are interlinked by additional water molecules via strong intermolecular O-HÁ Á ÁO hydrogen bonds into a three-dimensional network ( Fig. 4 and Table 2). There are additional C-HÁ Á ÁS and C-HÁ Á ÁO interactions, but most of the C-HÁ Á ÁS and C-HÁ Á ÁO angles are far from linearity and thus, they should represent relatively weak interactions (Table 2).

Synthesis and crystallization
General: Na 3 SbS 3 was prepared by the reaction of anhydrous Na 2 S (ABCR, 95%), Sb (99.5%, Sigma Aldrich) and sulfur (99%, ABCR) in a molar ratio of 3:2:3 at 870 K in a silica glass ampoule according to a literature procedure (Pompe & Pfitzner, 2013). The pale-yellow compound is sensitive to air and moisture and must be stored under a nitrogen atmosphere.

Figure 4
Crystal packing of the title compound viewed along the b axis with intermolecular O-HÁ Á ÁO and O-HÁ Á ÁS hydrogen bonds shown as dashed lines.

Experimental methods:
The XRPD measurements were performed by using a Stoe Transmission Powder Diffraction System (STADI P) with Cu K radiation that was equipped with a linear, positionsensitive MYTHEN detector from Stoe & Cie.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. Hydrogen atoms were positioned with idealized geometry and were refined with U iso (H) = 1.2U eq (C) using a riding model. Some of the water H atoms were located in a difference-Fourier map; their bond lengths were set to ideal values and finally they were refined isotropically with U iso (H) = 1.5U eq (O). The water H atoms that could not be located in a difference-Fourier map were included in idealized calculated positions that gave the most sensible geometry as donors for hydrogen bonds.
The crystal studied was twinned by non-merohedry around a pseudo twofold rotation axis, with a matrix close to 0 1 0 1 0 0 0 0 1 but refinement in SHELXL (Sheldrick, 2015) assuming this kind of twinning lead to only very poor reliability factors. Therefore, both individual domains were indexed separately and the overlapping reflections were removed. In this case, relatively good reliability factors were observed but the completeness was only 68.6%. Thus, the data were integrated neglecting the twinning, corrected for absorption and merged. Afterwards the twin law was determined and the data were transformed into HKLF-5 format (Sheldrick, 2015), leading to full completeness and acceptable reliability factors.