Synthesis and Spectroscopic Characterization of the New Sitting-atop Complexes from Reaction of Zirconyl Nitrate and Free Base meso-Tetraarylporphyrins in Mild Conditions

Abstract

A series of sitting-atop (SAT) complexes, [(ZrO)<TEX>$H_2t(X)pp(NO_3)_2$</TEX>], have been prepared via the reactions of free base meso-tetraarylporphyrins, <TEX>$H_2$</TEX>t(X)pp, with zirconyl nitrate hydrate, ZrO(N<TEX>$O_3)_2{\cdot}xH_2$</TEX>O. The products have been characterized by a variety of methods including <TEX>$^1H\;NMR,\;^{13}C$</TEX> NMR, IR and UV-Vis spectroscopies, elemental analysis and conductance measurements. The data indicate that the meso-tetraarylporphyrins coordinate with two pyrrolenine nitrogen atoms to the zirconyl cation located above the distorted porphyrin plane and two protons remain on the pyrrole nitrogens. Such half sandwich-type sitting-atop complexes may be considered as models for the initial steps of the metallation of the macrocycles.