112 



P. George, J. Beetlestone and J. S. Griffith 



In the discussions of electronic structure little use has been made of these 

 observations, and in the following sections it will be shown, first, that the 

 trend in spectroscopic properties parallels the trend in magnetic moments, 

 and secondly, that the data are quantitatively consistent with the view that 

 the hydroxides are thermal mixtures of high- and low-spin forms. 



QUALITATIVE CORRELATIONS BETWEEN THE MAGNETIC 

 MOMENTS AND THE SPECTRA OF FERRIHAEMOPROTEIN 



DERIVATIVES 



The close resemblance, which has long been recognized, between spectra of 

 the same derivative of different haemoproteins, is illustrated in Figs, 4 to 6 



^mM — 



4 — 





 650 



600 



550 



500 



/\(mjj) 



Fig. 4. Visible spectra of acidic ferrimyoglobin, ferrihaemoglobin and 

 ferriperoxidase (Keilin and Hartree, 1951 ; Hanania, 1953). 



in the case of the visible spectra of acidic ferrihaemoproteins and their 

 fluoride and cyanide complexes. Furthermore, all the high-spin ferric 

 complexes have visible spectra like the acidic ferrihaemoproteins and fluoride 

 derivatives, with an absorption band between 600 and 640 m// and a second 



