A Stable N-Hetero-Rh-Metallacyclic Silylene.

A cyclic (amino)metal-substituted dicoordinated silylene derivative has been synthesized and fully characterized. Of particular interest is that the N-hetero-Rh-I-metallacyclic silylene exhibits a distorted tetrahedral geometry around the rhodium atom and a considerably shortened Si-Rh bond (2.138 angstrom) compared to classical Si-Rh single bonds (ca. 2.30-2.35 angstrom). A theoretical investigation reveals that the geometrical deviation around the rhodium center from the classical square-planar to a tetrahedral geometry increases the pi-donating and sigma-accepting character of the rhodium atom, thereby efficiently stabilizing the silylene moiety.