Structures of the silver(I) complexes with maleic and fumaric acids: silver(I) hydrogen maleate, silver(I) maleate and silver(I) fumarate

Abstract

Abstract A series of silver(I) complexes with the unsaturated isomeric dicarboxylic acids, maleic and fumaric, has been prepared and the structures of three of these, silver(I) hydrogen maleate, (1), silver(I) maleate, (2) and silver(I) fumarate, (3), were determined by X-ray diffraction. All three structures are polymeric, with (1) and (2) based on bis(carboxylato-O,O′) dimers. With (1), a strong intramolecular hydrogen bond is found [O … O, 2.494(2) Å], involving the acidic proton and the cis-related carboxylate group. In this respect it is similar to maleic acid and other hydrogen maleates. With (2), a unique feature is the presence of an ethylene-Ag π-bond to one of the independent silver ions [Ag–C, 2.448(5) Å] giving angle distortion about the dimer unit. The polymeric structure of (3) is based on an unusual cyclic, open figure-eight Ag4 complex unit involving four different carboxylato-(O,O′) interactions. This results in three separate Ag … Ag contacts [2.924(1) Å, 2.925(1) Å, 3.090(1) Å].