Synthesis and structures of mono- and tetra-nuclear silver complexes of styrene-containing N-heterocyclic carbene

Two tetra-nuclear Ag(I) complexes with styrene-functionalized N-heterocyclic carbene [AgL2]2[Ag2X4] (L = 1-methyl-3-(4-vinylbenzyl)imidazol-2-ylidene, X = Cl, 2a; X = I, 2b) were prepared by the reactions between the corresponding imidazolium salts with Ag2O. The reaction mixture was further treated with AgBF4 to give a mononuclear ion-pair complex [AgL2][BF4] (3). The molecular structures of these new Ag(I) complexes have been determined by X-ray diffraction analyses. 2a and 2b consist of two [Ag(L)2]+ fragments with the central [Ag2X4]2− anion held together by the close Ag(I)–Ag(I) interactions. Complex 3 is a mononuclear ion-pair complex with a linear bi-coordinate Ag fragment.