SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF CIS-1,4-DIAMINOCYCLOHEXANETETRACHLOROPLATINUM(IV) - A NEW ANTITUMOR AGENT

cis-1,4-Diaminocyclohexanetetrachloroplatinum(IV), a new antitumor age nt, has been synthesized, where cis-1,4-diaminocyclohexane (cis-1,4-DA CH) is a novel carrier ligand. The structure of this complex has been determined by single crystal X-ray diffraction method. The crystal par ameters are as follows: space group P1BAR (triclinic), a=6.880(2), b=8 .177(3), c=11.784(4) angstrom, Z=2. The platinum has a slightly distor ted octahedral coordination with two adjacent corners being occupied b y the two amino nitrogens of cis-1,4-DACH, and the remaining two equat orial 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 bi nding to platinum. It forms a seven-membered chelating ring with plati num, leading to considerable strain in bidentate DACH binding. This st rain is evidenced by the large 125.7-degrees C-N-Pt angle. The N-Pt-N angle is expanded to 98.4-degrees owing to geometric constraints of th e cis-1,4-DACH geometry.