Spectroscopic studies on reversible reactions in compounds of the porphin series

CONTENTS
I. Introduction 153
II. Nomenclature and molecular structure of compounds of the porphin series 153
III. Isomerism and tautomeric changes 154
IV. Molecular compounds 155
V. Hydrogen exchange in compounds of the porphin series 160
VI. Hydrogenation and dehydrogenation of the pyrrole rings in compounds of the porphin series 161
VII. Reversible photochemical reduction of compounds of the porphin series 162