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Hydrosilylation Induced by N! Si Intramolecular Coordination: Spontaneous Transformation of Organosilanes into 1-Aza- SiloleType Molecules in the Absence of a Catalyst
Authors: Novák Miroslav | Dostál Libor | Alonso Mercedes | De Proft Frank | Růžička Aleš | Lyčka Antonín | Jambor Roman
Year: 2014
Type of publication: článek v odborném periodiku
Name of source: Chemistry - A European Journal
Publisher name: Wiley-VCH
Place: Weinheim
Page from-to: 2542-2550
Titles:
Language Name Abstract Keywords
cze Hydrosilylace řízená N-Si itramolekulární interakcí Cílená syntéza o přípravu intramolekulárně koordinovaných organosilánů (Ph2LSiH)-Si-1 (1a), (PhLSiH2)-Si-1 (2a), (Ph2LSiH)-Si-2 (3a), and (PhLSiH2)-Si-2 (4a) vedla k izolaci 1-aza-silolů, jako pruduktů spontální hysrosilylační reakce. Hydrosilylace; řízená; N-Si; itramolekulární; interakcí
eng Hydrosilylation Induced by N! Si Intramolecular Coordination: Spontaneous Transformation of Organosilanes into 1-Aza- SiloleType Molecules in the Absence of a Catalyst Our attempts to synthesize the NSi intramolecularly coordinated organosilanes (Ph2LSiH)-Si-1 (1a), (PhLSiH2)-Si-1 (2a), (Ph2LSiH)-Si-2 (3a), and (PhLSiH2)-Si-2 (4a) containing a CHN imine group (in which L-1 is the C,N-chelating ligand {2-[CHN(C6H3-2,6-iPr(2))]C6H4}(-) and L-2 is {2-[CHN(tBu)]C6H4}(-)) yielded 1-[2,6-bis(diisopropyl)phenyl]-2,2-diphenyl-1-aza-silole (1), 1-[2,6-bis(diisopropyl)phenyl]-2-phenyl-2-hydrido-1-aza-silole (2), 1-tert-butyl-2,2-diphenyl-1-aza-silole (3), and 1-tert-butyl-2-phenyl-2-hydrido-1-aza-silole (4), respectively. Isolated organosilicon amides 1-4 are an outcome of the spontaneous hydrosilylation of the CHN imine moiety induced by NSi intramolecular coordination. Compounds 1-4 were characterized by NMR spectroscopy and X-ray diffraction analysis. The geometries of organosilanes 1a-4a and their corresponding hydrosilylated products 1-4 were optimized and fully characterized at the B3LYP/6-31++G(d,p) level of theory. The molecular structure determination of 1-3 suggested the presence of a SiN double bond. Natural bond orbital (NBO) analysis, however, shows a very strong donor-acceptor interaction between the lone pair of the nitrogen atom and the formal empty p orbital on the silicon and therefore, the calculations show that the SiN bond is highly polarized pointing to a predominantly zwitterionic Si+N- bond in 1-4. Since compounds 1-4 are hydrosilylated products of 1a-4a, the free energies (G(298)), enthalpies (H-298), and entropies (H-298) were computed for the hydrosilylation reaction of 1a-4a with both B3LYP and B3LYP-D methods. On the basis of the very negative G(298) values, the hydrosilylation reaction is highly exergonic and compounds 1a-4a are spontaneously transformed into 1-4 in the absence of a catalyst. Hydrosilylation; Induced; Intramolecular; Coordination; Spontaneous; Transformation; Organosilanes; into; 1-Aza-; SiloleType; Molecules; the; Absence; Catalyst