Long-range coupling in cyclic silanes

Abstract

We report the synthesis of a mixed methyl- and hydro-substituted cyclosilane (1) possessing cis/trans stereoisomerism. Each diastereomer of 1 possesses distinct symmetry elements (cis-1: C_s-symmetric; trans-1: C₂-symmetric). Cyclosilane 1 is a model system to probe configuration- and conformation-dependent long-range proton–proton coupling. Extensive NMR spectroscopic characterization is reported, including one-dimensional ¹H NMR and ²⁹Si DEPT and INEPT+ spectra and two-dimensional ¹H–²⁹Si and ¹H–¹H correlated spectroscopy (HSQC, HMBC, COSY). On the basis of these experiments, molecular connectivity consistent with four-bond ¹H–¹H coupling is confirmed.