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Reaction of 1-phenyl-4-mono-or disubstituted thiosemicarbazides with platinum(I1,IV) salts affords the diamagnetic intensely colored neutral complexes Pt(C6Hb,R,R'-atf)s (8, R = R' = CH3; R = H, R' = CeH5, tert-CaH~). The nature of these complexes has been elucidated by a combination of electrochemical, epr, and electronic spectral studies. They have been shown to be the central members of five-membered electron transfer series Pt(C8Ha,R,R'-atf)zz whose component species (z = 2 --, 1--, 0, 1+, 2 + ) are interrelated by one-electron-transfer reactions. Polarographic half-wave potentials in acetonitrile solution occur in the range of ca. -1.2 to +0.8 V vs. sce. Cyclic voltammetric studies of the Pt(CaH5,tert-C4Ho-atf)gz series indicate reversible behavior for the processes 2 -1 -, 1t 0, and 0 * 1+ a t scan rates of 0.1-10 V/sec. Electronic spectra of all five members of this series are reported together with epr data for the spin-doublet z = 1 -, 1 + members of all three series This study provides a detailed demonstration of the validity of the electron-transfer series concept as applied to planar complexes containing unsaturated five-membered chelate rings.

Reaction of chloro[tetrakis(4-methoxyphenyl)porphinato]iron(III) with Zert-butyl hydroperoxide yields an isoporphyrin, hydroxo-or 10,15,-5/f,21/f-porphinato]iron(III), isolated as a microcrystalline solid. This compound is of interest as an example of an isoporphyrin generated by chemical rather than electrochemical oxidation and because it represents an alternative to the oxoiron species currently presumed to be involved in biomimetric oxidations utilizing peroxy acids and hydroperoxides mediated by (meso-tetraphenylporphinato)iron(III) complexes. The structure of the isoporphyrin has been established by its distinctive electronic spectrum with strong bands in the near-IR region, by high-field *H NMR, and by fast atom bombardment mass spectrometry. The presence of the peroxo linkage has been confirmed by redox titration, IR spectroscopy, and determination of elemental composition by high-resolution mass spectrometry. ZerZ-Butylperoxy substitution of the porphyrin ring has been confirmed by demonstrating that the peroxy functionality remains after treatment of the isoporphyrin with hydrogen chloride.

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