title: Negatively charged pi-(C60-)2 dimer with biradical state at room temperature.
abstract: A negatively charged pi-(C60-)2 dimer bonded by two single bonds was found in the ionic multicomponent complex {(MDABCO+).CoIITMPP}2.(C60-)2.(C6H4Cl2)2.5.(C6H5CN)1.5 (1). In contrast to the previously described diamagnetic sigma-(C60-)2 dimer, the negatively charged pi-dimer has a biradical state at room temperature: (C60*-)2 (S = 1). The behavior of spins in this dimer can be described by a model with a singlet ground state (S = 0) and a close lying excited triplet (S = 1) state with the energy gap of 2|JAF| = 70 +/- 2 cm-1. On the whole, complex 1 shows a strong antiferromagnetic interaction of spins with a Weiss constant of -34 K.
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. konarev@icp.ac.ru
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Konarev
authors.forename: Salavat S
authors.initials: SS
authors.lastname: Khasanov
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otsuka
authors.forename: Gunzi
authors.initials: G
authors.lastname: Saito
authors.forename: Rimma N
authors.initials: RN
authors.lastname: Lyubovskaya