The Dichloroplatinum(II) Complex of 5,5,7-Trimethyl-1,4-diazacycloheptane: Preparation, Crystal Structure and Binding to Nucleotides and DNA

Abstract

The preparation of [Pt(tmdz)Cl₂] (tmdz = 5,5,7-trimethyl-1,4-diazacycloheptane) is described. The crystal structure has been determined by X-ray diffraction methods and refined to an R value of 0·048 (764F). The crystals are triclinic, space group P ^-1, a 8·023(2), b 10·874(4), c 14·207(3) Å, α 95·34(3), β 94·96(2), γ 94·97(3)°. N.m.r. studies and molecular mechanics methods show that only one diastereomer of the complex—that observed in the crystal structure—is energetically accessible. In total DNA binding studies, [Pt(tmdz)Cl₂] binds less effectively and at a lower rate than cisplatin. The complex reacts with dG and d(GpG) to form a variety of isomeric products, as indicated by h.p.l.c. analysis.