Raman Study of the Pressure-Induced Charge Transfer Transition in the Neutral Donor-Acceptor Complexes {Ni(nPr₂dtc)₂}(C₆₀)₂ and {Cu(nPr₂dtc)₂}(C₆₀)₂

Abstract

Raman spectra of the neutral state donor–acceptor complexes {Ni(nPr₂dtc)₂}(C₆₀)₂ and {Cu(nPr₂dtc)₂}(C₆₀)₂ were measured at pressures up to 7 GPa and at room temperature. The splitting of the A_g(2) PP-mode of C₆₀ at ∼0.7 GPa is accompanied with redistribution of intensity from the high frequency component to the low frequency one that dominates the spectra at P > 2 GPa. Thus, the PP-mode shows an overall softening by ∼6 cm⁻¹ near 2 GPa, while the pressure dependence is reversible with some hysteresis. The observed peculiarities are associated with the pressure-induced charge transfer of one electron from the organic donor to the fullerene acceptor.

Keywords:

• Fullerene
• charge transfer
• pressure
• Raman spectra

Acknowledgments

The support by the Russian Foundation for Basic Research, grant № 11-02-00886 is greatly acknowledged.