94 III. PORPHYRIN CHEMISTRY 



and Dezelic {2634-) have shown that the ratio of the maximum absorption 

 of the two bands varies gradually from palladium (3.4) over zinc (1.1) to 

 mercury (0.9) ; while the copper complexes of most porphyrins have a stronger 

 first band, those of porphin and a few porphyrins have the second band 

 stronger (2643). Table X gives the position and relative strength of the 

 absorption maxima of some metal complexes of mesoporphyrin IX dimethyl 

 ester, according to Stern and Dezelic {2634), unless another reference is given. 



TABLE X 



Absorption Spectra of Metal Complex Salts of Mesoporphyrin Ester " 



All values but one according to Stern and Dezelic {263 't). 

 According to Fischer, Plotz, and Filser {H6o). 



Stern found the frequency difference, Aa.p, between the two bands prac- 

 tically the same for all the complex salts (1180-1'-2'-2j cm."^, except for the 

 nickel complex, for which it was larger iyilS cm."^), and the silver and lead 

 complexes, for which it was smaller (1134 and 995 cm.~^, respectively). The 

 sodium, potassium, magnesium, zinc, cadmium, and tin (Sn*+) salts fluoresce, 

 while others, e.g., the iron and copper salts, do not fluoresce {1167). While 

 the absorption spectrum of porphyrins is greatly altered, that of dihydro- 

 porphin comppunds and diazaporphyrins is much less influenced by the 

 combination with metals, e.g., magnesium or copper {2643). 



