Diastereomeric mixtures of epimers at metal of the α-amino carboxylate compounds [(η n-ring)M(Aa)Cl] [(η n- ring)M = (η 5-C 5Me 5)Rh(III), (η 5-C 5Me 5)Ir(III), (η 6-p- MeC 6H 4iPr)Ru(II); Aa = α-amino carboxylate] can be readily prepared from the corresponding acetylacetonate compounds [(η n-ring)M(acac)Cl]. In general, even below 0 °C, these complexes epimerise at the metal. The absolute configuration at the metal has been determined by X-ray diffractometric methods and NMR and CD spectroscopies. The molecular structures of the complexes [(η 5-C 5Me 5)M(Aa)Cl] [M(Aa) = Rh(l-Pro), Ir(l-Pro), Rh(MePro), Ir(MePro)] and [(η 6-p-MeC 6H 4iPr)Ru(Aa)Cl] (Aa = Hyp, MePhe, MePro) are reported. Related iodide complexes, [(η n-ring)M(Aa)I], can be prepared from the corresponding chlorides by halogen metathesis. © 2012 Elsevier B.V. All rights reserved.

We thank the Ministerio de Educación y Ciencia (Grant CTQ 2009-10303/BQU and CONSOLIDER INGENIO-2010 program under the project Factoría de Cristalización, CSD2006-0015) and Gobierno de Aragón (Grupo Consolidado: Catalizadores Organometálicos Enantioselectivos) for financial support. P. G. O. acknowledges financial support from the CSIC, “JAE-Doc” program, contract cofounded by the ESF.

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