Isotable mixed diorganocopper(I) complexes have been synthesized and structurally characterized by introducing a variety of bulky "Rind" groups based on a fused-ring octa-R-substituted s-hydrindacene skeleton. Treatment of RindLi with CuBr produced organobromocuprate dimers [Cu(Rind)/CuBr](2) or monomers Li[Cu(Rind)Br], depending on the steric bulkiness of the Rind ligands. Subsequent substitution of the bromine atoms in these complexes by lithium trimethylsilylacetylide gave dimeric and monomeric aryl(alkynyl)copper(l) complexes A and B, respectively. Complex B is the first isolable mixed diorganocuprate monomer formulated as LiCuRR' and was found to selectively undergo oxidative cross-coupling of two different organic groups on copper.