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

A new diphosphine ligand, N,N′-bis­(2-diphenylphosphinoethyl)­terephthalamide, dppeta, containing two amide groups, has been synthesized and shown to form complexes [Au2Cl2(μ-dppeta)]·2Me2SO, 1, with gold­(I) and [Ag2(O2CCF3)2(μ-dppeta)], 2, and [Ag2(OTf)2(OH2)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, dppetaO2, forms a ribbon polymer using the PO groups as hydrogen bond acceptors.