Peripherally-metallated porphyrins: preparations, spectroscopic properties and structural studies of trans-[PtBr(MDPP)(PPh3)2] (DPP = dianion of 5,15-diphenylporphyrin, M = MnCl, Co, Ni, Zn) and related meso-η1-organoplatinum porphyrins

Abstract

A series of meso-η¹-platiniometalloporphyrins comprising DPP (= dianion of 5,15-diphenylporphyrin) and the first row transition metal ions Mn(III), Co(II), Ni(II) and Zn(II) has been prepared. The syntheses, spectroscopy and voltammetry as well as crystal structures of several of these derivatives are reported. The –PtBr(PPh₃)₂ moiety attached to the macrocycle at the meso position is a strong electron donor, as shown by its effects on spectra, oxidation potentials and reactivity. The crystal structures of trans-[PtBr(MDPP)(PPh₃)₂]·0.5CH₂Cl₂, where M = Co (16), Ni (14) and Zn (17), and trans-[PtBr(NiDPPBr)(PPh₃)₂] were determined. The structures exhibit non-planar distortions of the macrocycle which are best described as hybrids of typical ruffled and saddled conformations.