Metallkomplexe mit biologisch wichtigen Liganden, LXV. Chirale Halbsandwich‐Komplexe von Cobalt(III), Rhodium(III), Iridium(III) und Ruthenium(II) mit α‐Aminosäureamid‐, Glycinnitril‐ und Peptidester‐Liganden

Metal Complexes with Biologically Important Ligands, LXV [1] . — Chiral Half‐Sandwich Complexes of Cobalt(III), Rhodium(III), Iridium(III), and Ruthenium(II) with α‐Amino Amide, Glycinenitrile, and Peptide Ester Ligands Cp * Co(CO)I 2 (Cp * = η 5 ‐C 5 Me 5 ), [(η 6 ‐arene)RuCl 2 ] 2 (arene = p ‐cymene, hexamethylbenzene), and [Cp * MCl 2 ] 2 (M = Rh, Ir) react with α‐amino amides and various peptide esters to give the N,O ‐chelate complexes [Cp * (I)Co — NH 2 C(H)(R 1 )C(NHR 2 )‐O] + ( 1 ), [(η 6 ‐arene)(Cl)Ru — NH 2 C(H)(R 1 )C(NHR 2 )O] + ( 2 ), and [CP * (Cl)M—NH 2 CH 2 C(NHR)O] + (M = Rh, Ir) ( 5 , in solution), respectively. In the solid state the ligands are η 1 N ‐bonded in 5 . By deprotonation of the peptide bond in 2 and 5 the neutral N, N ‐chelate complexes (η 6 ‐arene)(Cl)Ru — NH 2 C(H)(R 1 )C(O)‐N̊ 2 ( 6 ) and Cp * (Cl)M — NH 2 C(H)(R 1 )C(O)NR 2 (M = Rh, Ir) ( 7 ) have been obtained. Glycinenitrile is η 1 ‐bonded in (η 6 ‐ p ‐cymene)(Cl) 2 Ru(NH 2 CH 2 CN) ( 3 ) and Cp * (Cl) 2 Rh(NH 2 CH 2 CN) ( 4 ). Double deprotonated triglycine methyl ester is a N,N,N ‐tridentate ligand in (η 6 ‐C 6 Me 6 )Ru(NH 2 CH 2 C(O)NCH 2 C(O)‐NCH 2 CO 2 Me) ( 8 ). The anions of L ‐asparagine and of aspartame ( L ‐aspartyl‐ L ‐phenylalanine methyl ester) give the complexes 9–12 with tridentate O,N,O ‐ or O,N,N ‐chelate ligands. The crystal structures of 1d (L = glyglyOEt), 5a (L = glycinamide), 6e (L = glyglyOEt), and 7k (L = glyglyglyOEt) have been determined by X‐ray structural analysis.