Conformational control by halogen substitution and by crystallisation: a study of the molecular structures of CH(SiMe2H)3 and CH(SiMe2Br)3 by gas-phase electron diffraction, and ab initio molecular orbital calculations †

SARACEN ? molecular structures from theory and experiment: the best of both worlds

“…In CH(SiMe 2 -Br) 3 just three of these are significantly populated at the temperature of the GED experiment, and with the application of suitable restraints on difference parameters relating to the positions of the heavier atoms, the structures could be refined. 38 However, although the calculated abundances of the three conformers were 76, 15 and 9%, the data could only be fitted satisfactorily with approximately equal amounts of all three. If the bromine atoms are replaced by hydrogen, nine of the eleven conformers become significantly populated at the temperature of the experiment, 38 and in C[SiMe 2 H] 3 SiH 3 all eleven (Fig.…”

The gas-phase structure and some reactions of the bulky primary silane (Me3Si)3CSiH3 and the solid-state structure of the bulky dialkyl disilane [(Me3Si)3CSiH2]2

“…57 The Si-H bonds are also elongated to 1.492(5) Å from an unstrained value of 1.485(5) Å in MeSiH 3 determined from MW spectroscopy. 58 Si-H bond lengths do not change much in the gas-phase structures of similarly crowded molecules (HMe 2 Si) 3 CH 59 by Tsi] group. Similar observations were made when the gasphase structures of the analogous molecules (Me 3 Si) 3 SiCl 3 19 and (HMe 2 Si) 3 CSiH 3 20 were determined.…”

Hybrid polymeric systems bearing bulky derivatives of tris(trimethylsilyl)methane

“…TG-MS analysis of volatiles formed during the thermolysis in argon suggests that the decomposition proceeds via abstraction of bulky (Me 3 Si) 3 CR-fragments. 53 The length of central Si-C bonds within the T Si group is enlarged in order to release the steric congestion within the molecule 56,57 but according to the reported data, the fact has no inuence on the thermal decomposition of T Si -modied polymers. Pyrolysis of T Si (A)-silsesquioxanes in air proceeds via standard oxidation of H-C and C-Si bonds at 600-900 K. Interestingly, photolytic degradation (high energy ArF laser light) of polysiloxanes with Fig.…”