STRUCTURAL STUDIES AND REDOX REACTIVITY OF PLATINUM COMPLEXES OF 14-MEMBERED TETRAAZA MACROCYCLIC LIGANDS

Pt(II) monomeric complexes of N-containing macrocycles have been synth esized and characterized in solution by H-1 NMR, C-13 NMR, and electro spray mass spectroscopy (ESMS) and in the solid state by X-ray crystal lography. Crystals of [Pt(cyclam)](ClO4)(2) (cyclam = 1,4,8,11 -tetraa zacyclotetradecane) are orthorhombic, space group P2(1)cn, a = 9.596 ( 3), b = 14.595 (21), c = 24.8782 (20) Angstrom, Z = 8. The structure w as solved by direct methods and was refined by the full-matrix least-s quares method to R = 0.073 and R-w = 0.093 for 2976 reflections with I greater than or equal to 2.5 sigma(I). Crystals of [Pt(N-methylcyclam )]-(ClO4)(2) . CH3CN (N-methylcyclam = 1,4,8,11 tetramethyl-1,4,8,11-t etraazacyclotetradecane = NMe(4)cyclam = tmc) are orthorhombic, space group Pmcn, a = 9.574 (8), b = 14.116 (5), c = 17.5456 (15) Angstrom, Z = 4. The structure was solved by direct methods and was refined by t he full-matrix least-squares method to R = 0.067 and R-w = 0.091 for 2 216 reflections with I greater than or equal to 2.5 sigma(I). Cyclic v oltammetry and EPR spectroscopy have been used to study the redox reac tivity of the Pt(II) and Pt(IV) complex ions. The solution chemistry o f Pt(IV) complexes based on cyclam and N-methylcyclam was investigated by electrospray mass spectrometry. Electrospray mass spectral evidenc e has been obtained for the formation of [Pt(III)(cyclam)Cl-2](+) and [Pt(III)(N-methylcyclam)Cl-2](+) ions.