Sodium and potassium compounds of [(η6-benzenecarboxylate)Cr(CO)3] and [(η6-1,4-benzenedicarboxylate)Cr(CO)3]

Abstract

Reactions of [{η⁶-C₆H₅COOH}Cr(CO)₃] with sodium and potassium hydroxide resulted in the corresponding alkali metal derivatives [Na(H₂O)₃{η⁶-C₆H₅COO}Cr(CO)₃] and [K₂(H₂O)(CH₃OH)_1.5[{η⁶-C₆H₅COO}Cr(CO)₃]₂]. Deprotonation of [{η⁶-p-C₆H₄(COOH)₂}Cr(CO)₃] with sodium and potassium hydroxide gave the sodium compound [{Na(H₂O)₃}₂{η⁶-p-C₆H₄(COO)₂}Cr(CO)₃] and the potassium compound [{K₂(CH₃OH)(H₂O)₂}{η⁶-p-C₆H₄(COO)₂}Cr(CO)₃]. All substances form two-dimensional structures in the solid state. Hydrogen bonds are observed in all sodium complexes between some carboxylate groups and coordinated water molecules. The hydrogen bonds are an essential part of the network. As a result of the higher coordination number of the potassium atoms, the polymeric networks can be constructed by direct interaction of the oxygen atoms of the carboxylic anions with the alkali metal atom. No hydrogen bonds are observed in the potassium compounds. In all compounds, except those of [Na(H₂O)₃{η⁶-C₆H₅COO}Cr(CO)₃], the alkali metal atoms form isocarbonyl bridges to the chromium atoms.