Optical spectra and covalent chemistry of fulleropyrrolidines

Low-temperature vibronic spectra of two fulleropyrrolidines (1-methyl-3,4-FP and 1-methyl-2(4-pyridine)-3,4-FP) embedded in crystalline toluene matrix have been studied. Two-component composition of the spectra has been established and charge-transfer-excitation origin of the structureless component has been suggested. Fine-structured Shpol'skii spectra were observed for 1-methyl-3,4-FP, which made possible to perform the vibrational analysis of its vibronic spectra. General similarities of the absorption spectra of fulleropyrrolidines and C60 molecules along with significant difference in their details have been discussed. A detailed interpretation of the C60 spectra serves as a basis for analyzing the spectra of the derivatives. Quantum-chemical study is based on the effectively-unpaired- electron concept for the fullerene molecule. Computations have been performed for the singlet states of the molecules in unrestricted Hartree-Fock approximation implemented in AMI semiempirical quantum chemical codes of the CLUSTER-Z1 software. The population of the HOMO and LUMO of the molecules under study alongside with the lowering of the molecules symmetry have been proposed to explain the spectral features observed. © 2007 Wiley Periodicals, Inc.