First crystal structure determination and high-frequency EPR study of an organoarsanecopper radical complex

• Published in: Inorganic chemistry communications Vol. 6; no. 9; pp. 1196 - 1200
• Main Authors: Ye, Shengfa, Kaim, Wolfgang, Sarkar, Biprajit, Schwederski, Brigitte, Lissner, Falk, Schleid, Thomas, Duboc-Toia, Carole, Fiedler, Jan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2003
• Subjects: Arsane ligands; Copper complex; EPR; Radical complex; π Interaction; π Interaction; Copper complex; Arsane ligands; EPR; Radical complex
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/S1387-7003(03)00216-8

The red radical complex {(μ-bptz)[Cu(AsPh 3) 2] 2}(BF 4) 1, bptz=3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, was obtained as a stable species and characterized by X-ray crystallography, spectroelectrochemistry and EPR at 9.5 and 285 GHz. Comparison with the previously reported {(μ-bptz)[Cu(PPh 3) 2] 2}(BF 4) 2 reveals longer Cu-element bonds by about 0.1 Å but otherwise a similar “organic sandwich” structure involving intramolecular π(phenyl)–π(tetrazine)–π(phenyl) interactions, a 3+1 coordination at the copper(I) centers, and averaged tetrazine intraring bond distances. Reversible oxidation to a blue dication with an intense MLCT band at 650 nm occurs at −0.24 V vs. Fc +/o. EPR studies show the effect of the higher spin–orbit coupling constant of the As vs. P atoms through slightly larger g anisotropy as determined through high frequency measurements.