Flash Communication:Strained and Bimetallic Structuresof Rhodium and Iridium Germyl Complexes with Phosphinoamido Ligands

In the coordination chemistry of heavier tetrylenes (:ER₂, where E = Si, Ge, Sn, Pb), chelating P,N-donor ligands occupy a privileged position, though phosphinoamido ligands, [R₂P–NR′]⁻, have been barely investigated. Herein, we report the synthesis and structural characterization of such complexes, whose structures drastically differ depending on the group 9 metal precursor used. Strained four-membered {P–N–Ge–M} metallacycles (M = Rh, Ir) are produced from the reaction of phosphinoamido germylenes with [MCl₂Cp*]₂ precursors (Cp* = η⁵-C₅Me₅). At variance, [MCl(COD)]₂ dimers are not broken apart; instead, they afford bimetallic species featuring bridging phosphinoamido–germyl and chloride ligands between the two metals. All new compounds were isolated on a preparative scale and spectroscopically characterized and their structures confirmed by X-ray diffraction. Computational studies support the σ-donor character of the Ge–M interaction and the absence of significant π-backbonding.