Synthesis and structural characterization of a series of one-dimensional heteronuclear dirhodium-silver coordination polymers

Abstract

Herein, we describe the preparation of heteronuclear dirhodium-silver complexes by reaction between molecular Rh(II)-Rh(II) compounds [Rh 2 (μ-O 2 CR) 4 L 2 ] (R = Me, Ph (1), CH 2 OEt (2); L = solvent molecules) with paddlewheel structure and PPh 4 [Ag(CN) 2 ]. One-dimensional coordination polymers of (PPh 4 )n[Rh 2 (μ-O 2 CR) 4 Ag(CN) 2 ] n (R = Me (3), Ph (4), CH 2 OEt (5)) formula have been obtained by replacement of the two labile molecules in the axial positions of the paddlewheel structures by a [Ag(CN) 2 ] - bridging unit. The crystal structures of 3-5 display a similar arrangement, having anionic chains with a wavy structure and bulky (PPh 4 ) + cations placed between the chains. The presence of the (PPh 4 ) + cations hinders the existence of intermolecular Ag-Ag interactions although several C-H..pi; interactions have been observed. A similar reaction between [Rh 2 (μ-O 2 CCMe 3 ) 4 (HO 2 CCMe 3 ) 2 ] and PPh 4 [Ag(CN) 2 ] led to the molecular compound (PPh 4 ) 2 (Rh 2 (μ-O 2 CCMe 3 ) 4 [Ag(CN) 2 ]2) (6) by replacement of the axial HO 2 CCMe 3 ligands by two [Ag(CN) 2 ] - units. The trimethylacetate ligand increases the solubility of the complex during the crystallization favouring the formation of discrete heteronuclear species.