Metallophilic contacts in 2-C6F4PPh2 bridged heterobinuclear complexes: a crystallographic and computational study

Treatment of the bis(chelate) complex trans-[Pd(kappa(2)-2-C6F4PPh2)2] (7) with PMe3 gave trans-[Pd(kappaC-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(mu-2-C6F4PPh2)2MCl] [M = Cu (14), Ag (15), Au (16)], from which the corresponding salts [(Me3P)2Pd(mu-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(mu-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(mu-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) A] suggestive of attractive noncovalent (dispersion) interactions, a conclusion that is supported by theoretical calculations of the electron localization function and the noncovalent interactions descriptor.