Cornelia Vetter, C. Wagner, G. Kaluđerović
2009
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0
Influential Citations
26
Citations
Quality indicators
Journal
Inorganica Chimica Acta
Abstract
Abstract The reaction of [PtMe 3 (MeOH)(bpy)][BF 4 ] ( 1 ) with the thionucleobases 2-thiocytosine (SCy, 2 ) and 1-methyl-2-thiocytosine (1-MeSCy, 3 ) resulted in the formation of the complexes [PtMe 3 (bpy)(SCy- κS )][BF 4 ] ( 4 ) and [PtMe 3 (bpy)(1-MeSCy- κS )] [BF 4 ] ( 5 ), respectively. The complexes were characterized by 1 H and 13 C NMR spectroscopy as well as by single-crystal X-ray analyses of 4 · MeOH and 5 . In 4 · MeOH two strong hydrogen bonds (N4–H⋯N3′: N4⋯N3′ 2.976(7) A) between the thiocytosine ligands give rise to base pairing thus forming dinuclear cations [{PtMe 3 (bpy)(SCy- κS )} 2 ] 2+ . In both complexes the platinum atom is octahedrally coordinated [PtC 3 N 2 S] by three methyl ligands, the 2,2′-bipyridine ligand and the κS coordinated nucleobase (configuration index: OC -6-33). The structural investigations gave evidence that the sulfur atoms of the nucleobase ligands in 4 · MeOH and 5 have to be regarded as sp 3 and sp 2 hybridized, respectively. Thus, the ligand in 4 · MeOH has to be considered as the deprotonated thiol-amino form of thiocytosine being reprotonated at N1. In complex 5 the 1-MeSCy is coordinated in its thione-amino form. DFT-calculations of the base-paired dinuclear cation in 4 as well as of 4 itself gave proof of the strength of the hydrogen bond (8.5 kcal/mol) and exhibited that cation–anion interactions influence the conformation of the complex. In vitro cytotoxicity studies of 4 and 5 using nine different human tumor cell lines revealed moderate cytotoxic activity.