SYNTHESIS AND CRYSTAL-STRUCTURE OF A NEW ANTITUMOR AGENT - [PT(CIS-1,4-DIAMINOCYCLOHEXANE)(1,1-CYCLOBUTANEDICARBOXYLATE)]

The crystal structure of [Pt(cis-1,4-diaminocyclohexane) (1,1-cyclobutanedicarboxylate)].1 1/2H2O has been determined by X-ray diffraction. The crystal is monoclinic with space group P2(1)/c, a = 10.358(5), b = 21.887(6), c = 13.920(7) angstrom, beta = 107.26(3)-degrees and Z = 8. The platinum atom has slightly distorted square planar geometry, with two adjacent corners being occupied by two amino nitrogens of cis-1,4-diaminocyclohexane (1,4-DACH) and the remaining two positions occupied with two oxygens of 1,1-cyclobutanedicarboxylate. The DACH moiety is in a twist-boat conformation and makes a seven-membered chelating ring with platinum. The strain in bidentate 1,4-DACH binding with platinum is evidenced by the expansion of average N-Pt-N and Pt-N-C angles to 98.2-degrees and 123.4-degrees, respectively. The cyclobutane ring is nonplanar. There are two crystallographically independent molecules in the asymmetric unit surrounding the three water molecules. The equatorial planes of the two molecules are titled at 32-degrees to each other. The near edges are directly hydrogen-bonded, while the open side is hydrogen bonded through the water molecules.