ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Bis(toluene)chromium fulleride Cr(C7H8)2 C60 has been synthesized as a microcrystalline powder from C60 and Cr(C7H8)2 in toluene. One electron is transferred from the chromium complex to the fullerene resulting in a magnetic moment of about 2.5±0.2 μB at room temperature, which corresponds to two electron spins per formula unit. At 250 K a reversible phase transition from a primitive cubic high temperature paramagnetic phase to a triclinic low temperature dimer phase occurs. The high temperature phase (Pm3¯m, a=9.986 Å) is constituted of dynamically disordered fulleride anions and bis(toluene)chromium (I) cations in a CsCl-type arrangement. The low temperature modification is triclinic (P1¯, a=13.541 Å, b=13.864 Å, c=14.122 Å, α=120.59, β=91.78, γ=116.88) and carries one unpaired electron per formula unit (μ=1.72±0.01 μB), which according to ESR measurements is localized at the chromium site (giso=1.9870). The phase transition has been monitored by x-ray diffraction, ESR and solid state NMR spectroscopy as well as by SQUID measurements. All experimental results can consistently be described within the scenario of dimer formation of the C60 monoanions during the transformation. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1404989
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