Hydrogen and Halogen Bonding to Au(I) Fluorido Complexes

Abstract

The hydrogen bonding in the Au(I) complex [Au(F ⋅ HF)(SPhos)] (SPhos=dicyclohexyl(2’,6’-dimethoxy[1,1’-biphenyl]-2-yl)phosphane) (1 a ⋅ HF) has been analysed by IR and NMR measurements, revealing the formation of an unsymmetrical bifluoride moiety. The data are in excellent agreement with DFT calculations. Comparisons to analogous complexes bearing NHC (NHC=N-heterocyclic carbene) ligands demonstrated a comparable bonding situation. The identity of the halogen bond in the compound [Au(F ⋅ IC6F5)(SPhos)] (1 a ⋅ IC6F5) in CD2Cl2 has been estimated, and van't Hoff data for the equilibrium between [Au(F)(SPhos)] (1 a) and IC6F5 with [Au(F ⋅ IC6F5)(SPhos)] are ΔH0=−8.1(3) kJ mol−1 and ΔS0=−36(1) J (mol K)−1. The latter are also in agreement with DFT calculations. For all calculations, comparisons between an explicit and implicit solvent model were drawn. Single crystal X-ray diffraction studies were performed for [Au(F ⋅ 2IC6F5)(BrettPhos)] ⋅ 2IC6F5 (BrettPhos=2-(dicyclohexylphosphino)-3,6-dimethoxy-2’,4’,6’-triisopropyl-1,1’-biphenyl) (1 b ⋅ 4IC6F5) demonstrating the presence of halogen bonds to Au(I) fluorido complexes in the solid state.