Use of ionic liquids (ILs) for the IL-anion size-dependent formation of Cr, Mo and W nanoparticles from metal carbonyl M(CO)6 precursors

Abstract

Stable chromium, molybdenum and tungsten nanoparticles are obtained reproducibly by thermal or photolytic decomposition under argon from mononuclear metal carbonyl precursors M(CO)₆ (M = Cr, Mo, W) suspended in the ionic liquids BMim⁺BF₄⁻, BMim⁺OTf⁻ and BtMA⁺Tf₂N⁻ (BMim⁺ = n-butyl-methyl-imidazolium, BtMA⁺ = n-butyl-trimethyl-ammonium, Tf₂N = N(O₂SCF₃)₂, OTf = O₃SCF₃) with a very small and uniform size of 1 to 1.5 nm in BMim⁺BF₄⁻ which increases with the molecular volume of the ionic liquid anion to ∼100 nm in BtMA⁺Tf₂N⁻ [characterization by transmission electron microscopy (TEM), dynamic light scattering and transmission electron diffraction (TED) analysis].