Oxidation of [(PtCl2)-Cl-II(ethane-1,2-diamine-N,N '-dicarboxylic acid)] and ligand ring closure in the platinum(IV) oxidation state

Oxidation of the dichloroplatinum(II) complex of the potentially tetradenta te ligand ethane-1,2-diamine-N,N'-diacetic acid (H(2)enda) gives rise to a variety of products. A number of these species have been crystallographical ly characterized. [(PtCl2)-Cl-IV (enda)] as the hemihydrate crystallizes in the monoclinic space group P2(1)/a, with a 11.238(1), b 15.665(2), c 13.73 7(2) Angstrom, beta 109.44(1)degrees, and was refined to an R value of 0.03 0 on 3015F. [(PtCl2)-Cl-IV (enda)] as the monohydrate crystallizes in the o rthorhombic space group Pna2(1), with a 6.984(2), b 9.000(3), c 18.431(3) A ngstrom, and was refined to an R value of 0.025 on 992F. [(PtCl3)-Cl-IV (He nda)].H2O crystallizes in the orthorhombic space group Pbca, with a 11.741( 1), b 12.851(2), c 17.133(2) Angstrom, and was refined to an R value of 0.0 29 on 2015F. The major product is the ring-closed complex [(PtCl2)-Cl-IV (e nda)] and if the solution is heated under reflux for 24 h, this is the only product. In contrast, reaction of cis, trans-[(PtCl2)-Cl-IV (OH)(2) (ethan e-1,2-diamine)] with excess acetic acid was shown not to lead to displaceme nt of the hydroxo ligands.