From Cluster to Polymer: Ligand Cone Angle Controlled Syntheses and Structures of Copper(I) Alkynyl Complexes

Abstract

Copper(I) alkynyl complexes have attracted tremendous attention in structural studies, as luminescent materials, and in catalysis, and homoleptic complexes have been reported to form polymers or large clusters. Herein, six unprecedented structures of CuI alkynyl complexes and a procedure to measure the cone angles of alkynyl ligands based on their crystal structures are reported. An increase of the alkynyl cone angle in the complexes leads to a modulation of the structures from polymeric [((PhCCCC)Cu)2(NH3)]1, to that of a large cluster [(TripCCCC)Cu]20(MeCN)4, to a relatively small cluster [(TripCC)Cu]8 (Trip=2,4,6-iPr3-C6H2). The complexes exhibit yellow-to-red phosphorescence at ambient temperature in the solid state and the luminescence behavior of the Cu20 cluster is sensitive to acetonitrile.