Redox non-innocence of thioether macrocycles: Elucidation of the electronic structures of mononuclear complexes of gold(II) and silver(II)

Shaw, J.L.; Wolowska, J.; Collison, D.; Howard, J.A.K.; McInnes, E.J.L.; McMaster, J.; Blake, A.J.; Wilson, C.; Schroder, M.

Abstract

The mononuclear +2 oxidation state metal complexes [Au([9]aneS3)2]2+ and [Ag([18]aneS6)]2+ have been synthesized and characterized crystallographically. The crystal structure of the Au(II) species [Au([9]aneS3)2](BF4)2 shows a Jahn−Teller tetragonally distorted geometry with Au−S(1) = 2.839(5), Au−S(2) = 2.462(5), and Au−S(3) = 2.452(5) Å. The related Ag(II) complex [Ag([18]aneS6)](ClO4)2 has been structurally characterized at both 150 and 30 K and is the first structurally characterized complex of Ag(II) with homoleptic thioether S-coordination. The single-crystal X-ray structure of [Ag([18]aneS6)](ClO4)2 confirms octahedral homoleptic S6-thioether coordination. At 150 K, the structure contains two independent Ag(II)−S distances of 2.569(7) and 2.720(6) Å. At 30 K, the structure retains two independent Ag(II)−S distances of 2.615(6) and 2.620(6) Å, with the complex cation retaining 3-fold symmetry. The electronic structures of [Au([9]aneS3)2]2+ and [Ag([18]aneS6)]2+ have been probed in depth using multifrequency EPR spectroscopy coupled with DFT calculations. For [Au([9]aneS3)2]2+, the spectra are complex due to large quadrupole coupling to 197Au. Simulation of the multifrequency spectra gives the principal g values, hyperfine (A) and quadrupole (P) couplings, and furthermore reveals non-co-incidence of the principal axes of the P tensor with respect to the A and g matrices. These results are rationalized in terms of the electronic and geometric structure and reveal that the SOMO has ca. 30% Au 5dxy character, consistent with DFT calculations (27% Au character). For [Ag([18]aneS6)]2+, detailed EPR spectroscopic analysis confirms that the SOMO has ca. 26% Ag 4dxy character and DFT calculations are consistent with this result (22% Ag character).

Citation

Shaw, J., Wolowska, J., Collison, D., Howard, J., McInnes, E., McMaster, J., …Schroder, M. (2006). Redox non-innocence of thioether macrocycles: Elucidation of the electronic structures of mononuclear complexes of gold(II) and silver(II). Journal of the American Chemical Society, 128(42), 13827-13839. https://doi.org/10.1021/ja0636439

• Journal Article Type: Article
• Publication Date: 2006-09
• Journal: Journal of the American Chemical Society
• Print ISSN: 0002-7863
• Electronic ISSN: 1520-5126
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 128
• Issue: 42
• Pages: 13827-13839
• DOI: https://doi.org/10.1021/ja0636439
• Public URL: https://durham-repository.worktribe.com/output/1543746