δMM-πL Odd Electron Delocalization onto Aromatic Bridging Ligands in a Paramagnetic Dirhodium Complex and Intermolecular π-Stack Interaction in Crystal

• Published in: Bulletin of the Chemical Society of Japan Vol. 73; no. 3; pp. 657 - 668
• Main Authors: Kawamura, Takashi, Kachi, Hisanori, Fujii, Hiroshi, Kachi-Terajima, Chihiro, Kawamura, Yuzuru, Kanematsu, Naohiro, Ebihara, Masahiro, Sugimoto, Kunihisa, Kuroda-Sowa, Takayoshi, Munakata, Megumu
• Format: Journal Article
• Language: English
• Published: The Chemical Society of Japan 01.03.2000
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.73.657

The odd electron in the δRhRh* orbital of (3,1)-[Rh2(mhq)4py]+ (1+; Hmhq = 4-methyl-2-quinolinol) was estimated to be delocalized onto each π system of the four mhq bridges to the extent of ca. 9% based on its 1H NMR paramagnetic shifts. The experimental spin distribution in the mhq ligands is consistent with a model of mixing of the π HOMOs of the mhq ligands into the δRhRh* singly occupied molecular orbital (SOMO). In crystals of (3,1)-[Rh2(hq)4py] (2; Hhq = 2-quinolinol) and its cationic radical salts, 2 or 2+ molecules form intermolecular π-stack arrangements of hq ligands. Intermolecular interaction between 2+ molecules in crystal was studied by examining electronic spectra, magnetic susceptibility, ESR, and electrical conductance of its salts.