Side chain functionalized η5-tetramethyl cyclopentadienyl complexes of Rh and Ir with a pendant primary amine group

Conversion of 2-(2,3,4,5-tetramethylcyclopentadien)ethylamine tautomere C 5 Me 4 H 2 (CHCH 2 )NH 2 ( 1) with MCl 3 · n H 2 O (M = Rh, Ir) under acidic conditions gives the respective μ-chloro-bridged chelates [(η 5 -Me 4 Cp(CH 2 ) 2 NH 3 )RhCl 2 ] 2 Cl 2 ( 2) and [(η 5 -Me 4 Cp(CH 2 ) 2 NH 3 )IrCl 2 ] 2 Cl 2 ( 3) . The dimeric complexes are received as ammonium salts and thus display good solubility in strong donor solvents such as water and DMSO. Addition of triphenyl phosphine converts Rh-dimer 2 into the mononuclear phosphine complex 4 . Under basic conditions, no intramolecular coordination of the pendant NH 2 is observed and thus the primary amino group of 4 reacts selectively with succinic anhydride by formation of a peptide bond. Hence, the electrophilic metal center and the latent nucleophilic nitrogen, which represent complementary functionalities, can be addressed separately under the appropriate reaction conditions.