Synthesis, Characterization, and Coordination Chemistry of the 2-Azaphenalenyl Radical

• Published in: Journal of the American Chemical Society Vol. 125; no. 19; pp. 5786 - 5791
• Main Authors: Zheng, Shijun, Lan, Jie, Khan, Saeed I, Rubin, Yves
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 14.05.2003; Amer Chemical Soc
• Subjects: Aza Compounds - chemistry; Chemistry; Chemistry, Multidisciplinary; Electron Spin Resonance Spectroscopy; Exact sciences and technology; Free Radicals - chemistry; Kinetics; Models, Molecular; Organic chemistry; Physical Sciences; Polycyclic Aromatic Hydrocarbons - chemistry; Reactivity and mechanisms; Science & Technology; Thermodynamics; CRYSTAL; MAGNETIC-PROPERTIES; CHAINS; BIS(HEXAFLUOROACETYLACETONATO)COPPER(II); CYANIDE; MO method; Molecular structure; Nitrogen heterocycle; Organic free radical; EPR spectrometry; Theoretical study; Density functional method; Aromatic compound; Tricyclic compound; Experimental study; Thermodynamic properties; Chemical reactivity
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja029236o

The 2-azaphenalenyl radical 2 has been synthesized and characterized by ESR spectroscopy. Variable-temperature ESR measurements were carried out on both the phenalenyl (1) and the 2-azaphenalenyl (2) radicals. The phenalenyl radical 1 has the known propensity to dimerize at temperatures below 20 °C, but unexpectedly less so than originally reported. The first experimental measurement of bond dissociation enthalpy for the dimerization of the phenalenyl radical 1 was obtained in CCl4 (11.34 ± 0.11 kcal/mol) and toluene (9.8 ± 0.7 kcal/mol). The 2-azaphenalenyl radical 2 does not show a propensity to dimerize over the measurable temperature range (220−330 K), but does so in the presence of Cu(hfac)2 (hfac = hexafluoroacetylacetonate). The latter complex was characterized by X-ray crystallography.