Cobalt(III)-pyen systems as potential carriers of β-ketoester-based ligands.

Two cobalt(III) complexes containing different β-ketoesters, namely [Co(L1)(pyen)](ClO)·HO (1) and [Co(L2)(pyen)](ClO) (2) (pyen = N,N'-bis(pyridin-2-ylmethyl)ethylenediamine; L1 = methylacetoacetate; L2 = ethyl 4-chloroacetoacetate) have been prepared and investigated as prototypes of bioreductive prodrugs. The presence of β-ketoester and pyen ligands in 1 and 2, as well as the perchlorate counterions, was supported by IR spectroscopy and CHN elemental analysis. The composition molecular structure of both complexes was confirmed by NMR spectroscopy and ESI mass spectrometry.