Low-dimensional compounds containing bioactive ligands. Part II: Palladium(II) and platinum(II) complexes with clioquinol as carboplatin analogues

[Pt(CQ)2] and [Pd(CQ)2] (yellow and green) complexes (CQ = 5-chloro-7-iodo-quinolin-8-ol, clioquinol) were prepared as potential anticancer agents. X-ray structure analysis revealed that the yellow [Pd(CQ)2] complex is a molecular coordination compound with Pd central atoms square-planarly coordinated by nitrogen and oxygen atoms of two trans-arranged bidentate molecules of CQ. Non-bonding interactions between parallel neighboring molecules in this complex were also investigated. The crystal structures of microcrystalline [Pt(CQ)2] and green [Pd(CQ)2] complexes were not solved but according to the LeBail (profile fitting) mode of the Rietveld analysis, all three complexes are isostructural. The complexes were characterized by thermal analysis, which revealed that they are stable up to 250 (yellow and green [Pd(CQ)2]) and 230 °C ([Pt(CQ)2]) as well as IR spectroscopy, which proved the presence of CQ in all complexes, and by elemental analysis which confirmed composition of the complexes.

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► Syntheses and characterization of [M(CQ)2] complexes (M = Pd, Pt, CQ = clioquinol).
► [Pd(CQ)2] consists of Pd(II) atom and two N,O-chelate coordinated molecules of CQ.
► Long-range interactions are present in the structure of [Pd(CQ)2].
► According to the powder diffractograms, prepared complexes are isostructural.