Matched Ligands for Small, Stable Colloidal Nanoparticles of Copper, Cuprous Oxide and Cuprous Sulfide

Abstract This work applies organometallic routes to copper(0/I) nanoparticles and describes how to match ligand chemistries with different material compositions. The syntheses involve reacting an organo‐copper precursor, mesitylcopper(I) [CuMes] z (z=4, 5), at low temperatures and in organic solvents, with hydrogen, air or hydrogen sulfide to deliver Cu, Cu 2 O or Cu 2 S nanoparticles. Use of sub‐stoichiometric quantities of protonated ligand (pro‐ligand; 0.1–0.2 equivalents vs. [CuMes] z ) allows saturation of surface coordination sites but avoids excess pro‐ligand contaminating the nanoparticle solutions. The pro‐ligands are nonanoic acid (HO 2 CR 1 ), 2‐[2‐(2‐methoxyethoxy)ethoxy]acetic acid (HO 2 CR 2 ) or di(thio)nonanoic acid, (HS 2 CR 1 ), and are matched to the metallic, oxide or sulfide nanoparticles. Ligand exchange reactions reveal that copper(0) nanoparticles may be coordinated by carboxylate or di(thio)carboxylate ligands, but Cu 2 O is preferentially coordinated by carboxylate ligands and Cu 2 S by di(thio)carboxylate ligands. This work highlights the opportunities for organometallic routes to well‐defined nanoparticles and the need for appropriate ligand selection.