Shul'ga A M, Siniakov G N, Gurinovich G P
Biofizika. 1978 Jan-Feb;23(1):5-10.
It was shown on the basis of NMR-H spectra that the addition of proton to dianions of Zn-octaethylchlorine, Zn-octaethylporphin, and Zn-monoasaethioporphyrin results in the formation of products with the structure of alpha-dihydroflorine, alpha-florine, and gamma-florine respectively. This indicates that electron density greatly increases when the anions are formed in the centres which had a decreased density in the initial molecule.