Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds
As part of a systematic study on the structures of the mixed halide isothiocyanates, Sn<sup>II</sup>Hal(NCS), their single crystals were grown and structurally characterized. For Hal = F (<b>1</b>), the SnClF structure type was confirmed, while with Hal = Cl (<b>2</b...
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2025-06-01
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| author | Hans Reuter |
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| description | As part of a systematic study on the structures of the mixed halide isothiocyanates, Sn<sup>II</sup>Hal(NCS), their single crystals were grown and structurally characterized. For Hal = F (<b>1</b>), the SnClF structure type was confirmed, while with Hal = Cl (<b>2</b>), Br (<b>3</b>), and I (<b>4</b>), there are three isostructural compounds of a new structure type, and for Hal = Cl (<b>5</b>), there is a second modification of a third structure type. These structure types have been described with respect to the composition and coordination geometry of the first, second, and van der Waals crust coordination spheres and their dependence on the halogen size and thiocyanate binding modes. With respect to the first coordination spheres, all three structure types constitute one-dimensional coordination polymers. In <b>1</b>, “ladder”-type double chains result from μ<sub>3</sub>-bridging fluorine atoms, and in <b>2</b>–<b>4</b>, single-chains built up from μ<sub>2</sub>-halogen atoms are pairwise “zipper”-like interconnected via <i>κ</i><sup>2</sup><i>NS</i>-bridging NCS ligands, which manage the halogen-linked chain assembly in the double chains of <b>5</b>. Based on the octet rule, short atom distances are interpreted in terms of 2c-2e and various (symmetrical, quasi-symmetrical, and asymmetrical) kinds of 3c-4e bonds. Weak contacts, the topology of which suggests the extension of the latter bonding concept, are identified as electron-deficient, bifurcated tetrel bonds. |
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| publishDate | 2025-06-01 |
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| spelling | doaj-art-9e1a7eca9fb84b42a7d4fb77d305b0f42025-07-11T14:40:51ZengMDPI AGMolecules1420-30492025-06-013013270010.3390/molecules30132700Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e BondsHans Reuter0Chemistry, Department of Biology/Chemistry, Osnabrück University, Barbarastr. 7, D 49069 Osnabrück, GermanyAs part of a systematic study on the structures of the mixed halide isothiocyanates, Sn<sup>II</sup>Hal(NCS), their single crystals were grown and structurally characterized. For Hal = F (<b>1</b>), the SnClF structure type was confirmed, while with Hal = Cl (<b>2</b>), Br (<b>3</b>), and I (<b>4</b>), there are three isostructural compounds of a new structure type, and for Hal = Cl (<b>5</b>), there is a second modification of a third structure type. These structure types have been described with respect to the composition and coordination geometry of the first, second, and van der Waals crust coordination spheres and their dependence on the halogen size and thiocyanate binding modes. With respect to the first coordination spheres, all three structure types constitute one-dimensional coordination polymers. In <b>1</b>, “ladder”-type double chains result from μ<sub>3</sub>-bridging fluorine atoms, and in <b>2</b>–<b>4</b>, single-chains built up from μ<sub>2</sub>-halogen atoms are pairwise “zipper”-like interconnected via <i>κ</i><sup>2</sup><i>NS</i>-bridging NCS ligands, which manage the halogen-linked chain assembly in the double chains of <b>5</b>. Based on the octet rule, short atom distances are interpreted in terms of 2c-2e and various (symmetrical, quasi-symmetrical, and asymmetrical) kinds of 3c-4e bonds. Weak contacts, the topology of which suggests the extension of the latter bonding concept, are identified as electron-deficient, bifurcated tetrel bonds.https://www.mdpi.com/1420-3049/30/13/2700tin(II)coordination spherescoordination geometriesinterpenetration indicesbond valences3c-4e-bonds |
| spellingShingle | Hans Reuter Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds Molecules tin(II) coordination spheres coordination geometries interpenetration indices bond valences 3c-4e-bonds |
| title | Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds |
| title_full | Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds |
| title_fullStr | Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds |
| title_full_unstemmed | Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds |
| title_short | Mixed Halide Isothiocyanate Tin(II) Compounds, SnHal(NCS): Signs of Tetrel Bonds as Bifurcated Extensions of Long-Range Asymmetric 3c-4e Bonds |
| title_sort | mixed halide isothiocyanate tin ii compounds snhal ncs signs of tetrel bonds as bifurcated extensions of long range asymmetric 3c 4e bonds |
| topic | tin(II) coordination spheres coordination geometries interpenetration indices bond valences 3c-4e-bonds |
| url | https://www.mdpi.com/1420-3049/30/13/2700 |
| work_keys_str_mv | AT hansreuter mixedhalideisothiocyanatetiniicompoundssnhalncssignsoftetrelbondsasbifurcatedextensionsoflongrangeasymmetric3c4ebonds |