Metallophilic Contacts in 2-C 6 F 4 PPh 2 Bridged Heterobinuclear Complexes: A Crystallographic and Computational Study

Abstract

(Figure Presented) Treatment of the bis(chelate) complex trans-[Pd(κ2-2- <inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>] (7) with PMe<inf>3</inf> gave trans-[Pd(κC-2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>(PMe<inf>3</inf>)<inf>2</inf>] (13) as a mixture of syn- and anti-isomers. Reaction of 13 with CuCl, AgCl, or [AuCl(tht)] (tht = tetrahydrothiophene) gave the heterobinuclear complexes [(Me<inf>3</inf>P)<inf>2</inf>Pd(μ-2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>MCl] [M = Cu (14), Ag (15), Au (16)], from which the corresponding salts [(Me<inf>3</inf>P)<inf>2</inf>Pd(μ-2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>M]PF<inf>6</inf> [M = Cu (17), Ag (18), Au (19)] could be prepared by abstraction of the chloro ligand with TlPF<inf>6</inf>; 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(PMe<inf>3</inf>)] gave the zwitterionic complex [(Me<inf>3</inf>P)PdCl(μ-2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>Au] (24) in which the 2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf> ligands are in a head-to-head arrangement. In contrast, the analogous reaction with [AuCl(PPh<inf>3</inf>)] gave [(Ph<inf>3</inf>P)PdCl(μ-2-C<inf>6</inf>F<inf>4</inf>PPh<inf>2</inf>)<inf>2</inf>Au] (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. Show more