Synthesis and X-ray crystal structure of cis-1,4-diaminocyclohexanetetrachloroplatinum(IV): A new antitumor agent

cis-1,4-Diaminocyclohexanetetrachloroplatinum(IV), a new antitumor agent, has been synthesized, where cis-1,4-diaminocyclohexane (cis-i,4-DACH) is a novel carrier ligand. The structure of this complex has been determined by single crystal X-ray diffraction method. The crystal parameters are as follows: space group P1. (triclinic), a=6.880(2), b=8.177(3), c=11.784(4) Å, Z=2. The platinum has a slightly distorted octahedral coordination with two adjacent corners being occupied by the two amino nitrogens of cis-1,4-DACH, and the remaining two equatorial and two axial positions are bound to four chloride ions. The cis-1,4-DACH is in a twist-boat conformation, which is necessitated by binding to platinum. It forms a seven-membered chelating ring with platinum, leading to considerable strain in bidentate DACH binding. This strain is evidenced by the large 125.7° C-N-Pt angle. The N-Pt-N angle is expanded to 98.4° owing to geometric constraints of the cis-1,4-DACH geometry.