Reactivity of Stable 9-Sila- and 9-Germa-phenanthrenes

Abstract

In recent years much interest has been focused on [4n+2]p-electron aromatic systems containing a group 14 element, and we have succeeded in the syntheses and isolations of sila-, germa-, and stannna-aromatic compounds as stable compounds by taking advantage of kinetic stabilization with a bulky substituent, Tbt group. These metallaaromatic compounds were found to have aromatic character based on their molecular structures, spectroscopic properties, and reactivities. In this report, we present the reactivity of 9-silaphenanthrene 1 and 9-germaphenanthrene 2. Ligand exchange reactions of 1 and 2 with [Cr(CH₃CN)₃(CO)₃] afforded eta-6-type complexes 3 and 4, respectively. The molecular structures of 3 and 4 were confirmed by NMR spectroscopy and finaly established by X-ray crystallographic analysis. Reactions of 1 and 2 with carbonyl compounds and alkynes will also be described.