Di-, tri-, and tetranuclear silver(I) complexes of phenanthroline-functionalized NHC ligands

A few polynuclear silver(l) NHC complexes have been synthesized via the reactions of phenanthrolinefunctionalized imidazolium salts with Ag20 at room temperature. The structures of di-, tri-, and tetranuclear silver complexes were fully characterized. The two N-phenanthrolinylimidazolylidene ligands in [Ag-4(L-1)(4)1(PF6)(4) (1), lAg(2)(1,2)21(PF6)2 (2), and [Ag2(1,3)21(PF6)2 (3) are head-to-head arranged. Complex 1 contains a short ligand-unsupported Ag Ag bond being 3.152(1) A representing the first example of strictly linear Ag4 cluster stabilized by NHCs. Trinuclear [Ag3(L4)21(PF6)3 (4) of phenanthroline-bridged biscarbene ligands contains a linearly arranged Ag3 core. [Ag3(L5)21(PF6)3 (5) and lAg3(L4)21(PE6)3 (7) are also trinulear Ag(l) complexes. Binuclear [Ag2(L6)21(PF6)2 (6) exhibits a twisted macrocyclic structure with the Ag Ag separation at 3.162(1) A. In 1-4, the silver ions are held together by two ligands in close proximity with the Ag Ag distances between 2.810(1) and 2.922(1) A. The fluorescent properties of these silver complexes have also been briefly studied. (c) 2014 Elsevier BY. All rights reserved.