Synthesis, Characterization and Structures of Solvent-Mediated Na(I)–Pd Heterometallic Complexes Containing [Pd(barb)4]2− Units (Barb = 5,5-Diethylbarbiturate)

Abstract

Reaction of Na<inf>2</inf>[PdCl<inf>4</inf>] with the sodium salt of 5,5-diethylbarbituric acid (barbH) led to the formation of two complexes, [PdNa<inf>2</inf>(μ-barb)<inf>4</inf>(DMSO)<inf>2</inf>]·2H<inf>2</inf>O·DMSO (1), and {[PdNa<inf>2</inf>(μ-barb)<inf>4</inf>(H<inf>2</inf>O)]·3H<inf>2</inf>O}<inf>n</inf> (2). The complexes were characterized by elemental analysis, FT-IR, NMR, and X-ray crystallography. Complex 1 was crystallized from H<inf>2</inf>O/DMSO (1 : 1, v : v) and 2 was crystallized in H<inf>2</inf>O. Both complexes contain square planar [Pd(barb)<inf>4</inf>]2− moieties, in which Pd(II) is coordinated by four barb ligands via the negatively charged nitrogens. In addition to the coordination of a DMSO ligand, two Na(I) ions in 1 are bridged by carbonyl O of four barb ligands in the [Pd(barb)<inf>4</inf>]2− unit, while the Pd(II) and Na(I) ions in 2 are bridged by the barb ligands in a tetradentate bridging fashion leading to a 2-D polymeric network. The bridging of metal centers in both complexes result in a significantly short Na−Pd distance of ca. 2.95 Å. Contrary to 2, the coordination of DMSO to Na(I) in 1 avoids the extension of the polymeric structure. © 2016 Informa UK Limited, trading as Taylor & Francis Group.