The molecular structure and the puckering potential function of silacyclobutane as determined by gas electron diffraction and relaxation constraints from ab initio calculations

A gas-phase electron diffraction and quantum chemical investigation of the molecular structure of 1-bromosilacyclobutane

“…This finding confirms once more the validity of the Jonvik and Boggs rules which were developed more than two decades ago for cyclobutane derivatives [41][42][43]. The predicted correlation between the electronegativity of the substituent and the higher conformational stability of the equatorial form in cyclobutanes was repeatedly verified by us [44][45][46][47] and transferred to heterocyclobutanes [2,7].…”

“…These studies have clearly shown that earlier published Si-C and C-C bond distances [6] for the parent molecule silacyclobutane (SCB) contradict the systematic structural behavior we found within the haloginated SCB series [1,2]. Accordingly, we very recently have reinvestigated SCB [7] and the new structural parameters affirmed the systematic features that have been observed in the substituted derivatives.…”

“…With the present electron diffraction study of the structure and the conformational axial-equatorial equilibrium of MBSCB we completed the systematic investigation of silacyclobutane [7] and its monohalogenated derivatives [1][2][3][4][5].…”

Synchrotron-based far infrared study of the rotation-vibration-inversion spectrum of silacyclobutane below 500 cm−1: The ν29 and ν30 bands

“…The geometric parameters of the ring backbone were derived using isotopic substitution ( 13 C, 29 Si, 30 Si) and the ring puckering angle (31.1(4) o ) in the ground state compares favourably with that reported via ab initio methods (34.5 o , MP2/cc-pVTZ) 17 and gas phase electron diffraction (33.5 o ) experiments. 18 The use of synchrotron far infrared radiation as a light source for vibrational spectroscopy is another technological advance that holds great promise for probing small molecules with very high resolution (better than 0.001 cm -1 ). 19 The high photon flux of synchrotron radiation allows the study of low intensity spectral features as well as the use of narrow apertures to achieve the high resolution needed to unravel tunneling splittings and to characterize minor perturbations.…”

On the geometric structure, puckering potential and electronic transitions of monosilacyclobutanes and disilacyclobutanes – A theoretical study

“…Various experimental methods including microwave spectroscopy [17][18][19], infrared/ Raman spectroscopy [20][21][22][23][24][25], and gas electron diffraction [26][27][28][29][30] have been employed to elucidate the geometric structures of silacyclobutane and its substituted derivatives. At the same time, theoretical calculations of a variety of such molecules as silacyclobutane (SCB) [30][31][32], 1-methyl-1-silacyclobutane (MSCB) [25], 1,1-dimethyl-1-silacycolbutane (DMSCB) [27], 1,3-disilacyclobutane (DSCB) [33], and 1,1,3,3-tetramethyl-1,3-disilacyclobutane (TMDSCB) [28] have been reported in the literatures. In a recent study of the structures of silacyclobutane and its 1,1-dicholoro and 1,1-difluoro derivatives using ab initio calculations [32], AlSaadi and Laane have shown that the dihedral angles of puckering decreased in the two 1,1-disubstituted derivatives of SCB as a result of increasing electronegativity of the substituent.…”