Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines
A series of silylated 2-aminopyrimidines Me<sub>(4−<i>n</i>)</sub>Si(NHpyr)<i><sub>n</sub></i> (Me = methyl, NHpyr = pyrimid-2-ylamino, <i>n</i> = 1, 2, 3, 4), i.e., compounds <b>1</b>, <b>2</b>, <b>3</b>...
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MDPI AG
2023-06-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/13/7/990 |
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| author | Marcus Herbig Edwin Kroke Jörg Wagler |
| author_facet | Marcus Herbig Edwin Kroke Jörg Wagler |
| author_sort | Marcus Herbig |
| collection | DOAJ |
| description | A series of silylated 2-aminopyrimidines Me<sub>(4−<i>n</i>)</sub>Si(NHpyr)<i><sub>n</sub></i> (Me = methyl, NHpyr = pyrimid-2-ylamino, <i>n</i> = 1, 2, 3, 4), i.e., compounds <b>1</b>, <b>2</b>, <b>3</b>, and <b>4</b>, respectively, was prepared from a series of the respective chlorosilanes Me<sub>(4−<i>n</i>)</sub>SiCl<i><sub>n</sub></i> and 2-aminopyrimidine. Triethylamine was used as a sacrificial base. Compounds <b>1</b>, <b>2</b>, <b>3</b>, and <b>4</b> are solid at room temperature. They were analyzed using <sup>1</sup>H, <sup>13</sup>C, <sup>29</sup>Si NMR, and Raman spectroscopy, and their molecular structures were confirmed by single-crystal X-ray diffraction analyses. All structures exhibit intramolecular van der Waals contacts between the silicon atom and one nitrogen atom of the pyrimidine moiety. Thus, their Si coordination spheres can be interpreted as [4+<i>n</i>] coordinated capped tetrahedra. Intermolecular hydrogen bonds (N–H···N bridges between the Si-bound amino groups and the non-Si-capping pyrimidine N atoms) are a constant contributor to the solid-state structures of these compounds. Furthermore, compounds <b>2</b> and <b>4</b> exhibit N–H···N bridges which involve 50% of their Si-capping N atoms as hydrogen bridge acceptors. Consequently, 50% of the non-Si-capping pyrimidine N atoms are stabilized by C–H···N contacts. As a result of a particularly dense network of intermolecular hydrogen bridges, the melting point of Si(NHpyr)<sub>4</sub> (compound <b>4</b>) is higher than 300 °C. |
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| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-11T01:10:22Z |
| publishDate | 2023-06-01 |
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| series | Crystals |
| spelling | doaj.art-14f31294fdd9421589c8d7c33843d0912023-11-18T18:52:51ZengMDPI AGCrystals2073-43522023-06-0113799010.3390/cryst13070990Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-AminopyrimidinesMarcus Herbig0Edwin Kroke1Jörg Wagler2Institut für Anorganische Chemie, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyInstitut für Anorganische Chemie, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyInstitut für Anorganische Chemie, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyA series of silylated 2-aminopyrimidines Me<sub>(4−<i>n</i>)</sub>Si(NHpyr)<i><sub>n</sub></i> (Me = methyl, NHpyr = pyrimid-2-ylamino, <i>n</i> = 1, 2, 3, 4), i.e., compounds <b>1</b>, <b>2</b>, <b>3</b>, and <b>4</b>, respectively, was prepared from a series of the respective chlorosilanes Me<sub>(4−<i>n</i>)</sub>SiCl<i><sub>n</sub></i> and 2-aminopyrimidine. Triethylamine was used as a sacrificial base. Compounds <b>1</b>, <b>2</b>, <b>3</b>, and <b>4</b> are solid at room temperature. They were analyzed using <sup>1</sup>H, <sup>13</sup>C, <sup>29</sup>Si NMR, and Raman spectroscopy, and their molecular structures were confirmed by single-crystal X-ray diffraction analyses. All structures exhibit intramolecular van der Waals contacts between the silicon atom and one nitrogen atom of the pyrimidine moiety. Thus, their Si coordination spheres can be interpreted as [4+<i>n</i>] coordinated capped tetrahedra. Intermolecular hydrogen bonds (N–H···N bridges between the Si-bound amino groups and the non-Si-capping pyrimidine N atoms) are a constant contributor to the solid-state structures of these compounds. Furthermore, compounds <b>2</b> and <b>4</b> exhibit N–H···N bridges which involve 50% of their Si-capping N atoms as hydrogen bridge acceptors. Consequently, 50% of the non-Si-capping pyrimidine N atoms are stabilized by C–H···N contacts. As a result of a particularly dense network of intermolecular hydrogen bridges, the melting point of Si(NHpyr)<sub>4</sub> (compound <b>4</b>) is higher than 300 °C.https://www.mdpi.com/2073-4352/13/7/9902-aminopyrimidineaminosilanehydrogen bondingremote coordinationX-ray diffraction |
| spellingShingle | Marcus Herbig Edwin Kroke Jörg Wagler Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines Crystals 2-aminopyrimidine aminosilane hydrogen bonding remote coordination X-ray diffraction |
| title | Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines |
| title_full | Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines |
| title_fullStr | Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines |
| title_full_unstemmed | Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines |
| title_short | Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines |
| title_sort | molecular structures and intermolecular hydrogen bonding of silylated 2 aminopyrimidines |
| topic | 2-aminopyrimidine aminosilane hydrogen bonding remote coordination X-ray diffraction |
| url | https://www.mdpi.com/2073-4352/13/7/990 |
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