A well studied complex is tris(glycinato)cobalt(III). It is produced by the reaction of glycine with sodium tris(carbonato)cobalt(III).  Similar synthetic methods apply to the preparation of tris(chelates) of other amino acids.  
Commonly amino acid complexes are prepared by ligand displacement reactions of metal aquo complexes and the conjugate bases of amino acids:
:[PtCl]  +  2HNCH(R)CO  →  [Pt(HNCH(R)CO)]  +  4 Cl
Relevant to bioinorganic chemistry, amino acid complexes can be generated by the hydrolysis of amino acid esters and amides (en = ethylenediamine):
:[(en)CoOH(κ-HNCH(R)COEt)]  →  [(en)CoOH(κ-HNCH(R)CO)]  +  EtOH
Because their 5-membered MNCO chelate ring is rather stable, amino acid complexes represent protecting groups for amino acids, allowing diverse reactions of the side chains.