METAL-COMPLEXES OF BIOLOGICALLY IMPORTANT LIGANDS .92. HYDRIDOTRISPYRAZOLYLBORATO RHODIUM(III) COMPLEXES OF ALPHA-AMINO CARBOXYLATES AND PEPTIDES

Chiral chelate rhodium complexes Tp(Cl)RhNH2C(H)(R)CO2 and Tp(Cl)RhNH 2C(H)(R)CO2 (Tp = hydridotrispyrazolylborate, Tp=hydridotris(3,5-dime thylpyrazolylborate) were prepared and the ratio of diastereoisomers w ere determined. The diastereoisomers are remarkably stable towards epe rimization. The reaction of [TpRhCl(2)](2) with glycineamide gives the ionic complex [Tp(Cl)Rh(NH2CH2CONH2)(2)](+)[TpRhCl(3)](-) (15), where as the reaction of TpRh(Cl)(2)(HOMe) with glycine amide and di- and t riglycine esters in the presence of NaOMe affords the neutral complexe s 16-24, Tp(Cl)(2)Rh(NH2CH2CONHR), Tp*(Cl)Rh(NH2CH2NR) and Tp*(Cl)Rh( NH2CH2CONCH2CONCH2CO2Me), respectively. Amidine complexes (25, 26) wer e obtained from TpRh(Cl)(2)(NCMe) and glycyl glycine esters by nucleop hilic attack of the amino group to the carbon atom of coordinated acet onitrile. The structures of Tp(Cl)Rh(L-alaO), Tp*(Cl)Rh(L-trpO), 15 a nd 25 were determined by X-ray diffraction.