Alkyl Pyridinium Iodocuprate(I) Clusters: Structural Types and Charge Transfer Behavior

• Published in: ACS omega Vol. 3; no. 11; pp. 15281 - 15292
• Main Authors: Wheaton, Amelia M, Streep, Michaela E, Ohlhaver, Christopher M, Nicholas, Aaron D, Barnes, Francis H, Patterson, Howard H, Pike, Robert D
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 30-11-2018
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.8b01986

The reaction of copper­(I) iodide (CuI) and N-alkyl pyridinium (RPy+, R = H, Me, Et, n-propyl = Pr, n-butyl = Bu, n-pentyl = Pn, and n-hexyl = Hx) or N-butyl-3-substituted pyridinium (N-Bu-3-PyX+, X = I, Br, Cl, CN, and OMe) iodide salts yielded pyridinium iodocuprate­(I) salts. Crystal structures of iodocuprate ions coupled with RPy+ include {Cu3I6 3–} n (R = H), {Cu2I3 –} n (R = Me), {Cu3I4 –} n (R = Et), {Cu6I8 2–} n (R = Pr), and {Cu5I7 2–} n (R = Bu, Pn, Hx). The [N-Bu-3-PyX]+ ions were typically paired with the 1-D chain {Cu5I7 2–} n . Diffuse reflectance spectroscopy performed on the [N-Bu-3-PyX]+ iodocuprate salts revealed that increasing the electron withdrawing capacity of the [N-Bu-3-PyX]+ system reduced the absorption edge of the iodocuprate salt. Variable temperature emission spectra of several [N-Bu-3-PyX]+ compounds revealed two emission peaks, one consistent with a cluster-centered halide to metal charge transfer 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 depends on the organic cation substitution.