Preparative, X‐ray, and NMR Studies of the Interaction of Beryllium with Salicylic and <i>o</i>‐Cresotic Acid: Crystal Structures of (NH₄)₂[Be(C₆H₄OCO₂)₂] · 2.25 H₂O and Na₃[Be(C₇H₆OCO₂)(OH)(CO₃)Be(C₇H₆OCO₂)] · 8 H₂O

Abstract

Abstract The existence of well‐defined crystalline beryllium salicylate(2 – ) and bis[salicylato(2 – )]beryllate complexes as well as of their o ‐cresotate analogs is established. The structure of (NH 4 ) 2 [Be(C 6 H 4 OCO 2 ) 2 ] · 2.25 H 2 O has been determined by an X‐ray structure analysis. It contains a beryllate anion of the composition [Be(C 6 H 4 OCO 2 ) 2 ] 2– with two salicylate(2 – ) ligands acting as chelate ligands. The considerable 9 Be NMR chemical shifts observed for aqueous solutions of the pure compounds indicate in all cases the persistence of the complexation of the metal ion by the catecholate ligands. 9 Be NMR studies of aqueous solutions containing BeSO 4 · 4 H 2 O and sodium salicylate(1 – ) or sodium o ‐cresotate(1 – ) in the molar ratios 1:1 and 1:2 show that a variety of beryllium/salicylate(2 – ) and beryllium/ o ‐cresotate(2 – ) species are present in solution, the most prominent being Be(C 6 H 4 OCO 2 )‐(H 2 O) 2 and [Be(C 6 H 4 OCO 2 ) 2 ] 2– (and their o ‐cresotate analogs). From such solutions in contact with air, a novel dinuclear beryllium hydroxido/ o ‐cresotato(2 – )/carbonato complex of the stoichiometry Na 3 [Be 2 (OH)(CO 3 )(C 7 H 6 OCO 2 ) 2 ] · 8 H 2 O is isolated. According to an X‐ray analysis the compound contains a cyclic beryllate anion with two Be(C 7 H 6 OCO 2 ) chelate units linked by bridging hydroxide and carbonate anions. In the light of the ubiquitous availability of phenolic and carboxylic groups in many biomolecules, the finding of strong bonding of Be 2+ to these functions in aqueous solution is very important.