Conformational properties of 1-cyano-1-silacyclohexane, C5H10SiHCN: Gas electron diffraction, low-temperature NMR and quantum chemical calculations

Silacyclohexanes, Sila(hetero)cyclohexanes and Related Compounds: Structure and Conformational Analysis

“…The results are compiled in Table 4. For comparison, the recently published data for 1-cyano- [74] and 1-methoxy-1-silacyclohexane [75] as well as disubstituted silacyclohexanes with the phenyl group and Hlg = F, Cl [76] or other electronegative groups at silicon are included. Note, that 1-bromo-1-phenylsilacyclohexane has also been synthesized [77] but, because of low stability, its conformational analysis could not be performed.…”

Intramolecular inversions, structure and conformational behavior of gaseous and liquid N-cyanopiperidine. Comparison with other 1-cyanoheterocyclohexanes

“…Auxiliary basis sets (CABS) in the form of cc-pVnZ-F12/OptRI were used in all calculations [24]. Similar CCSD(T)/CBS protocols have been used in studies on silacyclohexanes [7].…”

“…For comparison, the free Gibbs energy barrier of ring inversion of 1-cyanosilacylohexane is ∆G # (e→a) =5.6(1) kcal/mol from NMR spectroscopy [7]. Thus, the short N-Cα bond nearly doubles the energy barrier of the ring inversion process as compared with the longer C-Si bond.…”

“…The investigation of equatorial-axial conformational preferences of carbonitrile group in saturated six-membered ring traces back to the 1960s. Both equatorial and axial conformers of cyanocyclohexane were found to exist in the gas phase and in solution [2][3][4][5] and for 1-cyanosilacycloxane in the gas phase [6,7].…”

At the Experimental Limit of the NMR Conformational Analysis: 29Si and 13C NMR Study of the Conformational Equilibrium of 1-Phenyl-1-tert-butylsilacyclohexane

“…Closing the circle by low-temperature NMR spectroscopy studied silacyclohexanes, let us consider the conformational equilibria of the mono- ( 2 ) and disubstituted ( 3 , 4 ) silacyclohexanes, as depicted in Scheme . In compounds 2 , the substituent X can be found in both equatorial (Me, SiH 3 , CN) and axial positions (F, CF 3 , Cl, Br, I, OMe, and NMe 2 ), − the latter unlike the case for the corresponding cyclohexanes, where they still remain equatorial. , …”