STRUCTURAL CORRELATIONS IN ALUMS

The crystal data for 57 SO4, SeO4 and BeF4 alums of alpha and beta typ e, with a general formula M(I)M(III)(XY4)2 . 12H12O, were extracted fr om literature. Multiple linear regression was employed in order to est ablish a correlation between the length of the unit cell axis (depende nt variable) and (1-2) the effective ionic radii of both M+ and M3+; ( 3) the mean X-Y distance; (4) Pauling's electronegativity of atom Y, ( 5) the alum type; (6) the orbital quantum number of M3+ ion and (7) th e number of d-electrons in the highest energy shell. The adjusted r2 s tatistics had a high value (0.986), thus enabling the use of the regre ssion equation for predictive purposes. The effective ionic radii for CH3NH3+, NH3OH+, N2H5+ and C(NH2)3+ ions were calculated in this way. Some notes on the stability and existence of particular alums are also given.