Five- and Six-Coordinated Silver(I) Complexes Formed by a Metallomacrocyclic Ligand with a "AuN" Donor Group: Observation of Pendulum and Linear Motions and Dual Phosphorescence.

The six-coordinated silver(I) complex [AuAg(μ-(PPh)py)(OTf)](OTf), (py = pyridine, OTf = CFSO), and the five-coordinated silver(I) complex [AuAg(acetone)(μ-(PPh)py)](PF), , were prepared by the reaction of the precursor complexes (OTf) and (PF), in which = [Au(μ-(PPh)py)], with 1 equiv of Ag(OTf) in dichloromethane and excess of Ag(PF) in a mixture of dichloromethane/acetone, respectively. Also, the five-coordinated silver(I) complex [AuAg(μ-(PPh)py)(py)(OTf)](OTf), , was obtained by the reaction of with pyridine. The clusters - were characterized using multinuclear NMR spectroscopy and elemental microanalysis. The single-crystal X-ray diffraction analysis revealed the octahedral and distorted square pyramidal geometries around the silver(I) centers in the crystal structures of and , respectively; a dynamic structure was observed for cluster due to pendulum motion of the Ag(pyridine) moiety, which was anchored in the metallomacrocyclic unit [Au(μ-(PPh)py)]. Although the crystal structure of did not display disorders for the silver atom and the acetone ligand similar to that observed for , the low-temperature NMR spectroscopies and calculations show a dynamic structure for cluster due to linear motion of the Ag(acetone) moiety. The reaction of the precursor complex (POF) with 2 equiv of Ag(POF) yielded the tetranuclear AuAg cluster [AuAg(POF)(μ-(PPh)py)](POF), , with a planar-shaped {AuAg} metal core in which alternating Au and Ag atoms occupy the tetragon vertices and showed a strong argentophillic interaction between the silver(I) centers. All clusters - are emissive in the solid state, and the origins of their emissive excited states were determined using time-dependent density functional theory calculations. Cluster showed a dual phosphorescence emission, which displays strong dependence of the contributions of each emissive component onto the excitation wavelength.