Polyfuryl(aryl)alkanes and their derivatives. 5. Cations and radicals in the polyfuryl(aryl)methane series

The perchlorates of trifuryl- and difuryl(aryl)carbene have been prepared by the oxidation of polyfuryl(aryl)-methanes with trityl perchlorate and have been characterized. The temperature dependence of the PMR and 13C NMR spectra of the cations suggests that they exist in solution in the form of various rotamers. X-ray diffraction has been used to establish that the tris(5-methyl-2-furyl)carbene perchlorate molecule is a symmetrical propeller in which each furan ring is twisted from the plane by 10.4°. Reduction of the corresponding perchlorates on a zinc mirror in tetrahydrofuran gives stable polyfuryl(aryl)-methane radicals which were recorded by ESR spectroscopy.