A Diphosphine Ligand with Amide Functionality and Its Complexes with Gold(I) and Silver(I): Self-Assembly of Sheet Structures

Abstract

A new diphosphine ligand, N, N ′-bis(2-diphenylphosphinoethyl)terephthalamide, dppeta, containing two amide groups, has been synthesized and shown to form complexes [Au 2 Cl 2 (μ-dppeta)]·2Me 2 SO, 1, with gold(I) and [Ag 2 (O 2 CCF 3 ) 2 (μ-dppeta)], 2, and [Ag 2 (OTf) 2 (OH 2 ) 2 (μ-dppeta)], 3, with silver(I). The ligand dppeta undergoes self-association by NH···O═C hydrogen bonding in a classical way, but the complexes 1, 2, and 3 undergo self-association through a combination of hydrogen bonding and either aurophilic bonding (complex 1 ) or secondary coordination (complexes 2 and 3 ). In all cases, sheet structures are formed by self-assembly, in which the bonding interactions occur in the interior, with the outer faces containing mostly phenyl groups. In contrast, the bis(phosphine oxide) derivative, dppetaO 2, forms a ribbon polymer using the P═O groups as hydrogen bond acceptors.