Pyrazine-bridged polymetallic Copper Iridium clusters

Abstract Single crystals of a unique heterometallic Cu-Ir cluster have been prepared and the structure revealed using X-ray crystallography. The cluster is polymetallic with two Cu10Ir3 cores bridged by a pyrazine ligand. Each polymetallic centre within the cluster contains three stabilising N-heterocyclic carbenes, four Cl ligands, and a non-bridging pyrazine. Notably, each Cu-Ir core is arranged in an unusual shape containing 13 vertices, 22 faces, and 32 sides. The atoms within each tridecametallic core are arranged in four planes, with 2, 4, 4, 3 metals in each plane. Ir atoms are present in alternate planes with an Ir site featuring in the peripheral bimetallic plane, and two Ir sites featuring on opposite sides of the non-adjacent tetrametallic plane. These clusters could have implications in materials chemistry, as metal organic frameworks often feature reactive sites bridged by linking pyrazine units. Furthermore, these clusters could exhibit interesting reactivity as short intermetallic distances show a high level of metalophilic interactions and such clusters could be suitable for electron transfer reactions and molecular capture and storage.