Metallophilic Contacts in 2‑C₆F₄PPh₂ Bridged Heterobinuclear Complexes: A Crystallographic and Computational Study

Treatment of the bis­(chelate) complex trans-[Pd­(κ2-2-C6F4PPh2)2] (7) with PMe3 gave trans-[Pd­(κC-2-C6F4PPh2)2­(PMe3)2] (13) as a mixture of syn- and anti-isomers. Reaction of 13 with CuCl, AgCl, or [AuCl­(tht)] (tht = tetrahydrothiophene) gave the heterobinuclear complexes [(Me3P)2Pd­(μ-2-C6F4PPh2)2­MCl] [M = Cu (14), Ag (15), Au (16)], from which the corresponding salts [(Me3P)2Pd­(μ-2-C6F4PPh2)2M]­PF6 [M = Cu (17), Ag (18), Au (19)] could be prepared by abstraction of the chloro ligand with TlPF6; 18, as well as its triflato (20) and trifluoroacetato (21) analogues, were also prepared directly from 13 and the appropriate silver salt. Reaction of 13 with [AuCl­(PMe3)] gave the zwitterionic complex [(Me3P)­PdCl­(μ-2-C6F4PPh2)2­Au] (24) in which the 2-C6F4PPh2 ligands are in a head-to-head arrangement. In contrast, the analogous reaction with [AuCl­(PPh3)] gave [(Ph3P)­PdCl­(μ-2-C6F4PPh2)2­Au] (25) with a head-to-tail ligand arrangement. Single crystal X-ray diffraction studies of complexes 14–21 show short metal–metal separations [2.7707(11)–2.9423(3) Å] suggestive of attractive noncovalent (dispersion) interactions, a conclusion that is supported by theoretical calculations of the electron localization function and the noncovalent interactions descriptor.