Alkyl Arylinium Iodocuprate Clusters: Structural and Spectroscopic Diversity
Wheaton, Amelia Marie
Wheaton, Amelia Marie
Abstract
The reaction of copper(I) iodide (CuI) and alkyl pyridinium, quinolinium, 4,4ʹ-bipyridinium iodides, and butyl 3-substituted pyridinium (where the substitution = I, Br, Cl, OMe, and CN) salts ([RPy]+[I]–, [RQn]+[I]–, [R2(4,4ʹ-Bpy)]2+[I]2–, and [Bu 3-PyX]+[I] –) in alcohol with recrystallization in acetonitrile (MeCN) yields salts comprised of the arylinium cation and iodocuprate(I) anion. The iodocuprate(I) ions show a variety of stoichiometric and structural types, ranging from the 1-D chain structure {[CuI2]–}n to the discrete cluster [Cu8I13]5–. A diverse range of anion types is particularly notable for [R2(4,4ʹ-Bpy)]2+, while [RPy]+, [RQn]+ and [Bu 3-PyX]+ are commonly paired with the 1-D chain {[Cu5I7]2–}n. Increasing the size of the organic cation alkyl chain appears to also increase the size of the iodocuprate anion, but only up to cations where R = Bu. Diffuse reflectance spectroscopy at 298 K was performed on the n-butyl – alkylated pyridinium, quinolinium, and substituted pyridinium salts (compounds 5, 9, and 18 – 22), and revealed that increasing the electron withdrawing capacity of the n-butyl arylinium system reduced the absorption edge of the iodocuprate salt. UV emission spectra at 298 and 78 K of compounds 5, 19, 20, and 22 showed two different emission peaks, one consistent with a cluster-centered halide to metal charge transfer (XMCT) and the other consistent with an intermolecular mixed halide/metal charge transfer to the organic cation. The emission intensity and emission wavelength of the mixed halide/metal to cation charge transfer (XMCCT) appears to depend on the organic cation substitution.
Description
Date
2018-04-01