Substituent effects on aurophilicity and π–π interaction in crystals of arylphosphine–Au(I) derivatives. Synthesis and X-ray structural studies of compounds (CX3C6H4)3PAuX and {(CF3)2C6H3}3PAuX

Substituent effects on aurophilic interactions have been explored by single-crystal X-ray diffraction methods for a series of Au(I) complexes of monodentate phosphines, R′3PAuX (X=Cl, Sph, and Spy). When a CF3 substituent is introduced at a meta position of the phenyl ring in (C6H5)3P, aurophilicity has been accrued in ClAuP(m-CF3C6H4)3. However, aurophilicity has been weakened by introducing two CF3 groups at both meta positions. When a CF3 substituent is substituted for a H atom in the para position or when a CH3 substituent is introduced in the meta and/or para positions, such an effect has not been observed for R′3PAuCl and R′3PAuSph. Most dimers constructed by aurophilicity appear to be reinforced by π–π interactions between the phenyl ring of the Sph ligand or the pyridine ring of the Spy ligand and one of the phenyl rings in the R′3P ligand. A novel ladder-like supra molecular architecture is created in the crystal of {3,5-(F3C)2C6H3}3PAuSph, and a tetramer is formed in the crystal of (C6H5)3PAuSpy by aurophilic and π–π interactions. Substituent effects on important bond lengths have been discussed.