Crystal structure of bis-(N,N'-di-methyl-thio-urea-κS)bis-(thio-cyanato-κN)cobalt(II).

Aleksej Jochim,Christian Näther,Inke Jess,Rastko Radulovic

doi:10.1107/s2056989020011111

Aleksej Jochim, Christian Näther + Show 2 more

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https://doi.org/10.1107/s2056989020011111

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Abstract

During systematic investigations on the synthesis of coordination polymers with Co(NCS)2 involving different thio-urea derivatives as coligands, crystals of the title compound Co(NCS)2(N,N'-di-methyl-thio-urea)2, or [Co(C3H8N2S)2(NCS)2], were obtained. These crystals were non-merohedric twins and therefore, a twin refinement using data in HKLF-5 format was performed. In the crystal structure of this compound, the CoII cations are coordinated by two N-terminally bonded thio-cyanate anions as well as two S-bonding N,N'-di-methyl-thio-urea mol-ecules, forming two crystallographically independent discrete complexes each with a strongly distorted tetra-hedral geometry. An intricate network of inter-molecular N-H⋯S and C-H⋯S hydrogen bonds can be found between the complexes. The thermogravimetric curve of the title compound shows two discrete steps in which all coligand mol-ecules have been emitted, which is also accompanied by partial decomposition of the cobalt thio-cyanate. If the measurement is stopped after the first mass loss, only broad reflections of CoS can be found in the XRPD pattern of the residue, which proves that this compound decomposes completely upon heating. However, at lower temperatures an endothermic signal can be found in the DTA and DSC curve, which corresponds to melting, as proven by thermomicroscopy.

Highlights

During systematic investigations on the synthesis of coordination polymers with Co(NCS)2 involving different thiourea derivatives as coligands, crystals of the title compound Co(NCS)2(N,N0-dimethylthiourea)2, or [Co(C3H8N2S)2(NCS)2], were obtained
Investigations on the synthesis, crystal structures and magnetic properties of coordination polymers based on transition-metal thiocyanates have become of increasing interest in recent years, which is due to the high structural diversity of the thiocyanate anion and its ability to mediate reasonable magnetic exchange
Many different transition-metal thiocyanate coordination compounds are known, our main interests focus on first-row transition-metal thiocyanate compounds with the general composition M(NCS)2(L)2 in which paramagnetic metal cations M are connected by pairs of -1,3 bridging thiocyanate anions into chains, while the remaining coordination sites are occupied by neutral coligands L, forming an octahedral coordination polyhedron

Summary

Chemical context

Investigations on the synthesis, crystal structures and magnetic properties of coordination polymers based on transition-metal thiocyanates have become of increasing interest in recent years, which is due to the high structural diversity of the thiocyanate anion and its ability to mediate reasonable magnetic exchange. With other metal cations different layer topologies are known in which, for example, trimers are formed instead of dimers, which are connected by single -1,3thiocyanate bridges (Kozıskovaet al., 1990; Kabesovaet al., 1990) or in which each metal cation is directly connected to four neighboring metal cations by single -1,3-thiocyanate bridges (McElearney et al, 1979; Werner et al, 2015c; Ðakovicet al., 2010) It is not clear by which parameters the formation of either chains or layers is promoted, a third isomer of composition Co(NCS)2(L) exists in which the thiocyanate anions are N-terminally coordinated, forming discrete tetrahedral complexes (Prananto et al, 2017; Neumann et al, 2018c; Hannachi et al, 2019). Types of chain are connected via C—HÁ Á ÁS hydrogen bonds between the N,N0-dimethylthiourea molecules, forming layers parallel to the ac plane (Fig. 4), which are further connected into a three-dimensional network by additional N—HÁ Á ÁSNCS hydrogen bonds

Supramolecular features

Synthesis and crystallization

Findings

Refinement