TY - JOUR
T1 - Low-energy vibrations in Sc2@C84 and Tm@C82 metallofullerenes with different carbon cages
AU - Krause, M.
AU - Hulman, M.
AU - Kuzmany, H.
AU - Kuran, P.
AU - Dunsch, L.
AU - Dennis, T. J.S.
AU - Inakuma, M.
AU - Shinohara, H.
N1 - Funding Information:
We acknowledge financial support by the European Commission, TMR network ERBFMRX-CT97-0155 and from the Fonds zur Förderung der Wissenschaftlichen Forschung in Austria, Project P11943. T.J.S.D. thanks the Japan Society for the Promotion of Science and the Alexander von Humbolt foundation for research fellowship during the course of his work. H.S. thanks the Japanese Ministry of Education, Science, Sport and Culture for the financial support of this study.
PY - 2000/3/28
Y1 - 2000/3/28
N2 - Raman scattering and infrared absorption is reported for various empty and filled fullerene isomers in the low-energy range below 600 cm-1 to clarify the influence of different carbon cage structures on the bonding strength between encapsulated metal ion and fullerene cage and to check the potential of vibrational spectroscopy for isomer identification. The spectra of three isomers of Tm@C82 and three isomers of Sc2@C84 were measured at room temperature. The results are compared to the response of the most abundant isomers of empty C84 as well as to data for C82 and C60. The vibrational structure of the higher empty fullerene cages C82 and C84 resembles a downshifted and split C60 spectrum. Moreover the spectra of the two C84 isomers exhibited only small differences due to the very similar molecular structure, i.e. identical hexagon indices and direct neighbourhood in the Stone-Wales conversion map. Larger differences of the low-energy cage modes were found for the Tm@C82 isomers and in particular for the Sc2@C84 isomers. This goes along with an increasing difference in hexagon indices and a larger distance on the Stone-Wales conversion map. Due to the charge transfer from the endohedral metal to the fullerene the low- energy cage modes are shifted in the same direction as the modes of C60 during the exohedral doping process with alkali metals. New lines induced by the endohedral scandium and thulium ions with almost complementary Raman and infrared intensities were found for Sc2@C84 below 200, around 250 and 260 cm-1 and for Tm@C82 at 116 to 118 cm-1 and at 42 cm-1. These vibrations were further identified as M-C(2n) stretching and M-C(2n) deformation modes. Only a minor influence of the cage isomerism on these modes was observed. This is consistent with a simple ionic picture for the interaction between carbon cage and encapsulated metal ion. It is the amount of metal to fullerene charge transfer and the distance of the oppositely charge centres which determine the carbon cage-metal ion bond strength. (C) 2000 Elsevier Science B.V.
AB - Raman scattering and infrared absorption is reported for various empty and filled fullerene isomers in the low-energy range below 600 cm-1 to clarify the influence of different carbon cage structures on the bonding strength between encapsulated metal ion and fullerene cage and to check the potential of vibrational spectroscopy for isomer identification. The spectra of three isomers of Tm@C82 and three isomers of Sc2@C84 were measured at room temperature. The results are compared to the response of the most abundant isomers of empty C84 as well as to data for C82 and C60. The vibrational structure of the higher empty fullerene cages C82 and C84 resembles a downshifted and split C60 spectrum. Moreover the spectra of the two C84 isomers exhibited only small differences due to the very similar molecular structure, i.e. identical hexagon indices and direct neighbourhood in the Stone-Wales conversion map. Larger differences of the low-energy cage modes were found for the Tm@C82 isomers and in particular for the Sc2@C84 isomers. This goes along with an increasing difference in hexagon indices and a larger distance on the Stone-Wales conversion map. Due to the charge transfer from the endohedral metal to the fullerene the low- energy cage modes are shifted in the same direction as the modes of C60 during the exohedral doping process with alkali metals. New lines induced by the endohedral scandium and thulium ions with almost complementary Raman and infrared intensities were found for Sc2@C84 below 200, around 250 and 260 cm-1 and for Tm@C82 at 116 to 118 cm-1 and at 42 cm-1. These vibrations were further identified as M-C(2n) stretching and M-C(2n) deformation modes. Only a minor influence of the cage isomerism on these modes was observed. This is consistent with a simple ionic picture for the interaction between carbon cage and encapsulated metal ion. It is the amount of metal to fullerene charge transfer and the distance of the oppositely charge centres which determine the carbon cage-metal ion bond strength. (C) 2000 Elsevier Science B.V.
KW - Carbon cage isomerism
KW - Endohedral metallofullerenes
KW - Fullerenes
KW - IR spectra
KW - Low-energy vibrations
KW - Metal-to- fullerene charge transfer
KW - Metal-to-fullerene bond
KW - Raman spectra
UR - http://www.scopus.com/inward/record.url?scp=0034724242&partnerID=8YFLogxK
U2 - 10.1016/S0022-2860(99)00451-2
DO - 10.1016/S0022-2860(99)00451-2
M3 - Article
AN - SCOPUS:0034724242
SN - 0022-2860
VL - 521
SP - 325
EP - 340
JO - Journal of Molecular Structure
JF - Journal of Molecular Structure
IS - 1-3
ER -