Au(I) and Ag(I) formamidinate tetranuclear complexes and coordination polymers: Synthesis, structures and luminescent properties

Abstract

Reactions of AuClS(CH3)2 and Ag(I) salts (AgSCN, AgOAc and AgSbF6) with the lithiated formamidines afforded the tetranuclear complexes [Au4(4-pyf)4]·4CH3OH [4-Hpyf = N,N’-bis(pyridine-4-yl)formamidine], 1, [Au4(pmf)4] [Hpmf = N,N’-bis(pyrimidine-2-yl)formamidine], 2, and [Ag4(pmf)4], 3, and the coordination polymers [Ag2(OAc)(4-pyf)]n, 4, and {[Ag2(4-pyf)2]·THF}n, 5, which have been structurally characterized by X-ray crystallography. The intramolecular Au⋯Au separations in 1 and 2 are in the range 2.8832(2)–3.3338(10) Å and the Ag⋯Ag separations in 3–5 are 2.7927(3)–2.9819(19) Å, indicating the existence of aurophilicity and argentophilicity, respectively. Complex 3 is a unique tetranuclear complex of the type Ag4(form)4 in which “form” represents the formamidinate ligands. The short lifetimes of 1.06–49.15 ns for 1–5 indicate that the emissions belong to fluorescence. Moreover, complex 4 emits white luminescence in the solid-state and the CIE coordinate appears at (0.30, 0.38), which represents the first single-emitting component white phosphor in the class of formamidinate coordination polymers.