A structural, spectroscopic and DFT theoretical comparison of the cis and trans isomers of a cyclohexasilane

Abstract

We report a synthesis of the trans and cis isomers of 1,4‐di‐tert‐butyl‐2,2,3,3,5,5,6,6‐octamethyl‐1,4‐diphenylcyclohexasilane (3), together with the solid‐state structure of cis‐3. Both isomers were characterized using multinuclear NMR and UV spectroscopies and were compared based on these data, together with DFT calculations. Remarkably, we found that both isomers of 3 showcase redshifted UV maxima when compared with other known cyclosilanes. To explain this, the theoretical calculations show that the transitions involved in the excited states of trans‐3 and cis‐3 have, in addition to the expected σ conjugation component of the Si6 ring, significant π contributions of phenyl substituents. The results presented herein show the effect of the substituent’s electronic properties regarding reactivity of intermediates, reaction yield, identity, and electronic properties of novel silicon‐containing molecules.