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  • 1
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    Online Resource
    Formation of Aromatic O ‐Silylcarbamates from Aminosilanes and Their Subsequent Thermal Decomposition with Formation of Isocyanates
    Wiley ; 2021
    In:  European Journal of Inorganic Chemistry Vol. 2021, No. 23 ( 2021-06-21), p. 2211-2224
    Details
    In: European Journal of Inorganic Chemistry, Wiley, Vol. 2021, No. 23 ( 2021-06-21), p. 2211-2224
    Abstract: A novel phosgene‐free route to different isocyanates starts from CO 2 and aminosilanes (cf. silylamines) to form so‐called carbamoyloxysilanes ( O ‐silylcarbamates), i. e., compounds with the general motif R 1 R 2 N−CO−O−SiR 3 R 4 R 5 as potential precursors. We focused on the insertion reaction of CO 2 into Si−N bonds of substrates with cyclic (mostly aromatic) amine substituents, i. e., PhNHSiMe 3 , (PhNH) 2 SiMe 2 , PhCH 2 NHSiMe 3 , p‐(MeO)C 6 H 4 NHSiMe 3 , o‐C 6 H 4 (NHSiMe 3 ) 2 , 1,2‐C 6 H 10 (NHSiMe 3 ) 2 , o‐C 6 H 4 (NHSiMe 3 )(CH 2 NHSiMe 3 ) and 1,8‐C 10 H 6 (NHSiMe 3 ) 2 . Compared to previously investigated aminosilanes these reactions are hindered due to the reduced nucleophilicity/basicity of the N‐atoms. Whereas slightly increased CO 2 pressure (8 bar) and prolonged reaction times (24 h) were sufficient to overcome hindrance of the insertion into, e. g., PhNHSiMe 3 , intermolecular effects in some two‐fold NHSiMe 3 functionalized substrates led to partial mono‐insertion (e. g., into o‐C 6 H 4 (NHSiMe 3 )(CH 2 NHSiMe 3 )) or intra‐molecular condensation of the intermediate insertion product in case of 1,8‐C 10 H 6 (NHSiMe 3 ) 2 to form 1H‐perimidin‐2(3H)‐one and other side products. Thermal treatment of mono‐silylated O‐silylcarbamates RHN−CO−O−SiR’ 3 resulted mainly in the formation of substituted ureas (RHN) 2 CO, whereas desired isocyanates could not be detected in these cases. Therefore, we continued our studies focussing on N,O ‐bissilylated precursors, which were obtained by an additional N ‐silylation of the O ‐silylated carbamates. This allowed the successful formation of isocyanates. As a sole byproduct hexamethyldisiloxane is formed. In all cases, known as well as yet unknown substances were characterised by 1 H, 13 C and 29 Si NMR spectroscopy, along with X‐ray diffraction analysis for crystallized solids.
    Type of Medium: Online Resource
    ISSN: 1434-1948 , 1099-0682
    URL: Issue
    URL: Article
    DOI: 10.1002/ejic.v2021.23
    DOI: 10.1002/ejic.202100118
    RVK:
    VA 4072.5
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1475009-0
    detail.hit.zdb_id: 1409951-2
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  • 2
    Online Resource
    Online Resource
    Lactamomethylsilanes – Synthesis, Structures, and Reactivity towards CO 2 and Phenylisocyanate
    Wiley ; 2019
    In:  Zeitschrift für anorganische und allgemeine Chemie Vol. 645, No. 3 ( 2019-02-15), p. 377-387
    Details
    In: Zeitschrift für anorganische und allgemeine Chemie, Wiley, Vol. 645, No. 3 ( 2019-02-15), p. 377-387
    Abstract: Lactamomethylsilanes of γ‐butyrolactam, δ‐valerolactam, ε‐caprolactam, and 1‐isoindolinone (phthalimidine) with up to three methyl moieties were synthesized according to the chemical formula Me x SiLac (4– x ) ( x = 0, 1, 2, and 3). Using the lactams as starting materials four synthetic routes were tested: salt elimination, transsilylation, transamination, and metallation of the lactames followed by reaction with methylchlorosilanes. All products were analyzed by NMR ( 1 H, 13 C and 29 Si) and RAMAN spectroscopy. Selected solid products were crystallized and the molecular structure was determined by single‐crystal X‐ray diffraction. The reactivity of the lactamomethylsilanes towards phenylisocyanate and CO 2 was studied.
    Type of Medium: Online Resource
    ISSN: 0044-2313 , 1521-3749
    URL: Issue
    URL: Article
    DOI: 10.1002/zaac.v645.3
    DOI: 10.1002/zaac.201800424
    RVK:
    VA 8102
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 201094-X
    detail.hit.zdb_id: 1481139-X
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  • 3
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    Online Resource
    New cyclic and spirocyclic aminosilanes
    Walter de Gruyter GmbH ; 2021
    In:  Main Group Metal Chemistry Vol. 44, No. 1 ( 2021-01-01), p. 51-72
    Details
    In: Main Group Metal Chemistry, Walter de Gruyter GmbH, Vol. 44, No. 1 ( 2021-01-01), p. 51-72
    Abstract: New cyclic and spirocyclic aminosilanes were synthesised using ethylenediamine, 2-aminobenzylamine, 1,8-diaminonaphthalene, o-phenylenediamine, and trans -cyclohexane-1,2-diamine as starting material. These diamines were converted into aminosilanes using silicon tetrachloride and dimethyldichlorosilane directly and via the N,N’ -bis(trimethylsilylated) amino derivatives. 15 new compounds of the type (diamino)(SiMe 3 ) 2 , (diamino) 2 Si, (diamino)SiMe 2 , and (diamino)SiCl 2 have been prepared. The formation of two cyclotrisilazane derivatives was observed starting from ( N,N’ -2-aminobenzylamino)dichlorosilane by trimerisation. All synthesised compounds have been characterised with NMR-, Raman-, or IR-spectroscopy, mass-spectrometry, and boiling or melting point. Single-crystal X-ray structure analyses of several derivatives have been performed. The degree of substitution with trimethylsilyl groups in the final compounds depends on the ring size of the spirocycles. It was shown with quantum chemical calculations on the M062X/6-31G(d) level that trimethylsilyl groups have a stabilising effect on 5-membered ring systems and a destabilising effect on 6-membered rings in these compounds.
    Type of Medium: Online Resource
    ISSN: 2191-0219 , 0792-1241
    URL: Article
    DOI: 10.1515/mgmc-2021-0007
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 640138-7
    detail.hit.zdb_id: 2602433-0
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  • 4
    Online Resource
    Online Resource
    CO 2 Capture with Silylated Ethanolamines and Piperazines
    Wiley ; 2020
    In:  ChemistryOpen Vol. 9, No. 9 ( 2020-09), p. 893-893
    Details
    In: ChemistryOpen, Wiley, Vol. 9, No. 9 ( 2020-09), p. 893-893
    Abstract: Invited for this month's cover is the group of Marcus Herbig from the TU Bergakademie in Freiberg. The cover picture shows the reaction of CO 2 with a silyl derivative of the biogenic amine ethanolamine. The role of CO 2 as a contributor to climate change makes “carbon capture” a desirable goal. However, in addition to simply capture CO 2 , aminosilanes form silylcarbamates, which represent starting materials for a variety of crucial chemicals. Thus, the entrapped CO 2 represents a useful C 1 building block. The ESF‐funded Junior Research Group CO 2 ‐Sil at the TU Bergakademie Freiberg (represented by their Logo and location) pursues that kind of goals. CO 2 ‐Sil studies these key reactions of CO 2 insertion in depth by syntheses, quantum chemical calculations and calorimetric experiments. CO 2 brought to the ground by our method shall be feedstock for various branches in chemistry. Read the full text of their Full Paper at 10.1002/open.201900269 .
    Type of Medium: Online Resource
    ISSN: 2191-1363 , 2191-1363
    URL: Issue
    URL: Article
    DOI: 10.1002/open.v9.9
    DOI: 10.1002/open.202000212
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2655605-4
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  • 5
    Online Resource
    Online Resource
    Historische Präparate für alle
    Wiley ; 2023
    In:  Nachrichten aus der Chemie Vol. 71, No. 5 ( 2023-05), p. 10-13
    Details
    In: Nachrichten aus der Chemie, Wiley, Vol. 71, No. 5 ( 2023-05), p. 10-13
    Abstract: Clemens Winkler, ab 1873 Professor für anorganische Chemie an der Bergakademie Freiberg, schmolz seine Entdeckungen, darunter verschiedene Germaniumverbindungen, in Glasampullen ein. Damit begründete er die Sammlung anorganisch‐chemischer Präparate der TU Freiberg, die die Universität heute noch in der Lehre einsetzt. Jetzt wird diese Sammlung digitalisiert.
    Type of Medium: Online Resource
    ISSN: 1439-9598 , 1868-0054
    URL: Issue
    URL: Article
    DOI: 10.1002/nadc.v71.5
    DOI: 10.1002/nadc.20234134105
    RVK:
    VA 6120
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2000386-9
    detail.hit.zdb_id: 2375969-0
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  • 6
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    Online Resource
    Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines
    MDPI AG ; 2023
    In:  Crystals Vol. 13, No. 7 ( 2023-06-21), p. 990-
    Details
    In: Crystals, MDPI AG, Vol. 13, No. 7 ( 2023-06-21), p. 990-
    Abstract: A series of silylated 2-aminopyrimidines Me(4−n)Si(NHpyr)n (Me = methyl, NHpyr = pyrimid-2-ylamino, n = 1, 2, 3, 4), i.e., compounds 1, 2, 3, and 4, respectively, was prepared from a series of the respective chlorosilanes Me(4−n)SiCln and 2-aminopyrimidine. Triethylamine was used as a sacrificial base. Compounds 1, 2, 3, and 4 are solid at room temperature. They were analyzed using 1H, 13C, 29Si 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+n] 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 2 and 4 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)4 (compound 4) is higher than 300 °C.
    Type of Medium: Online Resource
    ISSN: 2073-4352
    URL: Article
    DOI: 10.3390/cryst13070990
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2661516-2
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  • 7
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    Online Resource
    Insertion of CO2 and related heteroallenes into the Si–N-bond of methyl(N-morpholino)silanes
    Elsevier BV ; 2018
    In:  Inorganica Chimica Acta Vol. 473 ( 2018-03), p. 20-28
    Details
    In: Inorganica Chimica Acta, Elsevier BV, Vol. 473 ( 2018-03), p. 20-28
    Type of Medium: Online Resource
    ISSN: 0020-1693
    URL: Article
    DOI: 10.1016/j.ica.2017.12.020
    RVK:
    VA 4810
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
    detail.hit.zdb_id: 1484441-2
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  • 8
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    Online Resource
    Front Cover: CO 2 Capture with Silylated Ethanolamines and Piperazines (ChemistryOpen 9/2020)
    Wiley ; 2020
    In:  ChemistryOpen Vol. 9, No. 9 ( 2020-09), p. 890-890
    Details
    In: ChemistryOpen, Wiley, Vol. 9, No. 9 ( 2020-09), p. 890-890
    Type of Medium: Online Resource
    ISSN: 2191-1363 , 2191-1363
    URL: Issue
    URL: Article
    DOI: 10.1002/open.v9.9
    DOI: 10.1002/open.202000213
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2655605-4
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  • 9
    Online Resource
    Online Resource
    CO 2 Capture with Silylated Ethanolamines and Piperazines
    Wiley ; 2020
    In:  ChemistryOpen Vol. 9, No. 9 ( 2020-09), p. 894-902
    Details
    In: ChemistryOpen, Wiley, Vol. 9, No. 9 ( 2020-09), p. 894-902
    Abstract: Amine treatment is commonly used to capture CO 2 from exhaust gases and from ambient air. The Si−N bond in aminosilanes is capable of reacting with CO 2 more readily than amines. In the current study we have synthesized trimethylsilylated ethanolamines, diethanolamines and piperazines and investigated their reaction toward CO 2 . All products were characterized by 1 H, 13 C, and 29 Si NMR, RAMAN spectroscopy as well as mass spectrometry. The product of a twofold CO 2 ‐insertion into bis‐trimethylsilylated piperazine was analysed by single‐crystal X‐ray diffraction. Furthermore, quantum chemical calculations (DFT) were used to supplement the experimental results. Geometry optimizations and NBO calculations for each starting material were carried out at the B3LYP level with different basis sets. DFT calculations at the B3LYP, WB97XD and M062x level were conducted for geometry optimization and frequency calculations to examine the thermochemical data. The calculations were carried out both for the gas phase and in solvent environment. The calculated reaction enthalpies varied between −37 and −107 kJ mol −1 , while experimental values around −100 kJ mol −1 were determined.
    Type of Medium: Online Resource
    ISSN: 2191-1363 , 2191-1363
    URL: Issue
    URL: Article
    DOI: 10.1002/open.v9.9
    DOI: 10.1002/open.201900269
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2655605-4
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  • 10
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    Online Resource
    Insertion of phenyl isocyanate into mono- and diaminosilanes
    Walter de Gruyter GmbH ; 2017
    In:  Zeitschrift für Naturforschung B Vol. 72, No. 11 ( 2017-11-27), p. 909-921
    Details
    In: Zeitschrift für Naturforschung B, Walter de Gruyter GmbH, Vol. 72, No. 11 ( 2017-11-27), p. 909-921
    Abstract: The aminosilanes Me n Si(NRR′) 4− n ( n =2,3) with NRR′=ethylamino (NHEt), n -propylamino (NH n Pr), sec -butylamino (NH s Bu), n -octylamino (NH n Oct), n -dodecylamino (NH n Dodec), allylamino (NHAll), tert -butylamino (NH t Bu), diethylamino (NEt 2 ), and anilino (NHPh) were synthesized and their reactions with phenyl isocyanate were studied. In all cases of these silanes Me 3 SiNRR′ and Me 2 Si(NRR′) 2 formal insertion of the –NCO group into their Si–N bonds was observed, i.e. formation of products with Si–N (rather than Si–O) bonds was found. In some cases, the products could be crystallized and their molecular structures have been elucidated with single-crystal X-ray diffraction analyses.
    Type of Medium: Online Resource
    ISSN: 1865-7117 , 0932-0776
    URL: Article
    DOI: 10.1515/znb-2017-0149
    RVK:
    WA 15000
    RVK:
    VA 8360
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2017
    detail.hit.zdb_id: 2078109-X
    detail.hit.zdb_id: 124635-5
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