Equilibria in acidic solutions of chromium(III) perchlorate

MOF catalysts in biomass upgrading towards value-added fine chemicals

“…Metal ions polarize and thereby increase the acidity of their aqua ligands. For [CrIJH 2 O) 6 ] 3+ , 99,100 [CrBr(en)(H 2 O) 3 ] 2+ , 101 102 and some other Cr(III) aqua-amine complexes 103 the first aqua-proton dissociation constant is estimated at pK a ≈4. The first acid dissociation constants for [Cr(III)(NH 3 ) n (OH 2 ) 6−n ] 3+ lie between 4.4 and 5.3 depending on the number of aqua ligands and their cis, trans, fac or mer orientation.…”

On the Nature of Sandwiched Chromium Complexes in Exchanged alpha-Zirconium Phosphate

“…Dried intercalated solids show two bands near 429 and 594 nm. It is currently admitted that d-d transition bands shift towards the lower energy region in proportion as chromium species form an extended structure; the position of the bands of the pentaquahydroxy complex [Cr(OH)(OH 2 ) 5 ] 2+ , which are seen at 430 and 590 nm following 26,27 , and of chromium hydroxide indicate that the correlation is not straightforward, since the latter compound is built from hydrogen bonded monomeric [Cr(OH) 3 (H 2 O) 3 ] complexes 28 . The experimental data rather suggest that the partial charge on the chromium atom should be considered to be responsible for the shift.…”

The effect of pressure on the hydrolysis equilibria of aqueous metal ions

“…Determination of K at Atmospheric Pressure The procedure followed was similar to that described by Emerson and Graven (7). Chromium nitrate solution (ca.…”