Template Synthesis of Ruthenium Complexes with Saturated and Benzannulated NH,NH-Stabilized N-Heterocyclic Carbene Ligands

Reaction of [RuCl 2 ( p -cymene)] 2 with 2-azidoethyl isocyanide ( 1a ) or 2-azidophenyl isocyanide ( 1b ) leads to the isocyanide complexes [RuCl 2 ( p -cymene)( 1a )] [ 2a ] and [RuCl 2 ( p -cymene)( 1b )] [ 2b ], respectively. Complex [ 2a ] reacts with triphenylphosphine to yield the complex with a phosphinimine-substituted isocyanide ligand [ 3 ]. The attempted hydrolysis of the phosphinimine group in [ 3 ] with HCl·Et 2 O produced the complex with a protonated phosphinimine ligand [ 4 ]Cl instead of the expected complex with a 2-aminoethyl isocyanide ligand. An alternative method for the reduction of the azido group in [ 2a ] and [ 2b ] using FeCl 3 /NaI has been applied leading to complexes with the 2-amino-substituted isocyanide ligands, which undergo intramolecular ring closure to yield the complexes of type [RuI 2 ( p -cymene)(NHC)], [ 5a ] and [ 5b ].