Homopiperazine Pt(II) adducts with DNA bases and nucleosides: Crystal structure of [PtII(homopiperazine)(9-ethylguanine)2](NO3)2

A series of platinum(II) mono- and diadducts of the type [PtII(hmp)XCl]NO3 and [PtII(hmp)X2](NO3)2 (where hmp = homopiperazine and X = adenine, 9-ethylguanine, 7-methylguaninine, cytosine, 1-methylcytosine, or cytidine), have been synthesized and characterized by elemental analysis and by 1H, 13C, and 195Pt nuclear magnetic resonance spectroscopy. The crystal structure of diadduct [PtII(homopiperazine)(9-ethylguanine)2](NO3)2 was determined using a single crystal X-ray diffraction method. In this complex, platinum had a slightly distorted square planar geometry owing to the presence of a geometrically strained 5-membered ring. The two adjacent corners of the platinum plane were occupied by the two amino nitrogens of hmp, whereas the other two equatorial positions were occupied by two nitrogen atoms of two 9-ethylguanine. The 9-ethylguanine ligands are oriented in a head to tail fashion between 9-ethylguanine and platinum coordination plane possessing approximate C2 molecular symmetry.

Graphical abstractA series of homopiperazine-Pt(II) mono and diadducts with purine and pyrimidines nucleobases and nucleosides have been synthesized and characterized by 1H, 13C, 195Pt NMR. The crystal structure of one of these complexes [PtII(homopiperazine)(9-EtGua)2](NO3)2 is also reported here.Figure optionsDownload full-size imageDownload as PowerPoint slide