Neutral and ionic complexes of C60 with metal dibenzyldithiocarbamates. Reversible dimerization of C60*- in ionic multicomponent complex [Cr(I)(C6H6)2*+].(C60*-).0.5[Pd(dbdtc)2].
New molecular complexes of C60 with metal(II) dibenzyldithiocarbamates, M(dbdtc)2.C60.0.5(C6H5Cl), where M=Cu(II), Ni(II), Pd(II), and Pt(II) and an ionic multicomponent complex [Cr(I)(C6H6)2*+].(C60*-).0.5[Pd(dbdtc)2] (Cr(C6H6)2: bis(benzene)chromium) were obtained. According to IR, UV-visible-NIR, and EPR spectra, involve neutral components, whereas 5 comprises neutral Pd(dbdtc)2 and C60*- and Cr(I)(C6H6)2*+ radical ions. The crystal structure of at 90 K reveals strongly puckered fullerene layers alternating with those composed of Pd(dbdtc)2. The Cr(I)(C6H6)2*+ radical cations are arranged between the layers. Fullerene radical anions form pairs within the layer with an interfullerene C...C contact of 3.092(2) A, indicating their monomeric state at 90 K. This contact is essentially shorter than the sum of van der Waals radii of two carbon atoms, and consequently, C60*- can dimerize. According to SQUID and EPR, single-bonded diamagnetic (C60-)2 dimers form in below 150-130 K on slow cooling and dissociate above 150-170 K on heating. The hysteresis was estimated to be 20 K. For the (C60-)2 dimers in, the dissociation temperature is the lowest among those for ionic complexes of C60 (160-250 K). Fast cooling of the crystals within 10 min from room temperature down to 100 K shifts dimerization temperatures to lower than 60 K. This shift is responsible for the retention of a monomeric phase of at 90 K in the X-ray diffraction experiment.
Konarev
Dmitri V
DV
Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. konarev@icp.ac.ru
Kovalevsky
Andrey Yu
AY
Otsuka
Akihiro
A
Saito
Gunzi
G
Lyubovskaya
Rimma N
RN