- Insertion of phenyl isocyanate into monoand diaminosilanes
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The aminosilanes MenSi(NRR')4-n (n = 2,3) with NRR' = ethylamino (NHEt), n-propylamino (NHnPr), sec-butylamino (NHsBu), n-octylamino (NHnOct), n-dodecylamino (NHnDodec), allylamino (NHAll), tert-butylamino (NHtBu), diethylamino (NEt2), and anilino (NHPh) were synthesized and their reactions with phenyl isocyanate were studied. In all cases of these silanes Me3SiNRR' and Me2Si(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.
- Kraushaar, Konstantin,Herbig, Marcus,Schmidt, Dana,Wagler, J?rg,B?hme, Uwe,Kroke, Edwin
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p. 909 - 921
(2018/01/19)
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- From CO2 to polysiloxanes: Di(carbamoyloxy)silanes Me 2Si[(OCO)NRR′]2 as precursors for PDMS
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Double insertion of carbon dioxide into the Si-N bonds of diaminosilanes of the type Me2Si(NRR′)2 gives di(carbamoyloxy)silanes Me2Si[(OCO)NRR′]2. The reactions proceed exothermically and quantitatively in most cases. A comprehensive analysis of the CO2-insertion products including single-crystal X-ray structure analyses was carried out. Quantum chemical calculations indicate an activation energy of about 124 kJ/mol for both the first and the second insertion and support the exothermal nature of the reaction. Investigation of the thermal decomposition of the di(carbamoyloxy)silanes Me2Si[(OCO)NRR′] 2 reveals the formation of oligo- and polysiloxanes. Depending on the thermolysis parameters, isocyanates, amines, and/or ureas are formed in addition to the siloxanes. Various methods were applied to study the decomposition process and to identify and quantify the products, including thermal analyses, mass spectrometry, and FTIR and NMR (solution and solid-state) spectroscopy. The overall reaction scheme provides a novel route to polysiloxanes which uses carbon dioxide as an oxygen source.
- Kraushaar, Konstantin,Wiltzsch, Conny,Wagler, Joerg,Boehme, Uwe,Schwarzer, Anke,Roewer, Gerhard,Kroke, Edwin
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experimental part
p. 4779 - 4785
(2012/10/07)
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- Synthesis and characterisation of novel zirconium(IV) derivatives containing the bis-amido ligand SiMe2(NRR′)2
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The silicon compounds SiMe2(NRR′)2 [NRR′ = NMe2 (1), NEt2 (2), NC4H8 (3), NHEt (4), NHiPr (5), NHtBu (6), NMeBu (7)] have been synthesised via aminolysis of the dichloro species SiMe2Cl 2 and their ligating ability has been investigated towards zirconium(IV). The dimer zirconium compound {Zr[(NiPr) 2SiMe2]2}2 (8) has been synthesised by reacting ZrCl4 with the lithium salt Li2[(N iPr)2SiMe2] and its molecular structure has been determined in the solid state by X-ray diffraction analysis. The reaction of ZrCl4 with SiMe2(NRR′)2 yields the Lewis adducts ZrCl4[(NRR′)2SiMe2] [NRR′ = NMe2 (10), NC4H8 (11), NHEt (12), NHiPr (13), NHtBu (14), NMeBu (15)]. On the other hand, the mixed amido derivative Zr(NMe2)3(NHMe)[(N′Bu) SiMe2(NH′Bu)] (9) has been obtained from the reaction of Zr(NMe2)4 with SiMe2(NHtBu) 2. The solution molecular structure and dynamics of the zirconium derivatives have been elucidated by 1D and 2D multinuclear NMR spectroscopy.
- Passarelli, Vincenzo,Benetollo, Franco,Zanella, Pierino,Carta, Giovanni,Rossetto, Gilberto
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p. 1411 - 1418
(2007/10/03)
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