Coordination and C-H Activation of an Amidobis(phosphaalkene) Ligand at Rhodium(I)

Abstract

Phosphaalkkenes are an underrepresented class of phosphorus-based ligands that hold great potential for the stabilisation of low-valent transition metal and main group fragments. We present the synthesis of a monoanionic PNP type bis-phosphaalkene ligand and its reactions with [Rh(cod)(Cl)]2 which furnish two unique dinuclear Rh(I) complexes. These complexes show C-H activation of the Mes* groups of the PNP ligand and the presence of three different phosphaalkene coordination modes, respectively. Computational analyses suggests the presence of a unique Rh−Rh donor-acceptor interaction in the C-H activated complex. Stabilisation of the desired tricoordinate PNP supported Rh(I) species is possible in presence of the strongly donating CO ligand, yielding a mononuclear square-planar complex of the type [(PNP)Rh(CO)].