Novel ferrocenyl functionalised phosphinecarboxamides: synthesis, characterisation and coordination

The synthesis of two novel ferrocenyl-substituted phosphinecarboxamides, FcNHC(O)PH₂ (1; Fc = ferrocenyl) and FcCH₂NHC(O)PH₂ (2), is reported. These two primary phosphines were obtained by the reaction of aminoferrocene with sodium 2-phosphaethynolate in the presence of a proton source or, directly, from aminomethylferrocene hydrochloride and sodium 2-phosphaethynolate. Their ability to act as ligands was probed via reactions of 1 with rhodium(iii) and ruthenium(ii) precursors. The isoelectronic metal complexes [(η⁵-C₅Me₅)RhCl₂(1-κP)] and [(η⁶-mes)RuCl₂(1-κP)] were obtained. Treatment of these compounds with a base resulted in HCl elimination to afford phosphide-bridged dirhodium and diruthenium complexes highlighting that on coordination to a metal, the P-H bonds of these phosphinecarboxamides become increasingly protic.