MAGNETIC PROPERTIES OF C60H36 ISOMERS

摘要

The computed [GIAO (Gauge Including Atomic Orbitals)-SCF/tzp(He),dz(C,H)//SCF/3-21G endohedral helium NMR chemical shifts for various He@C60H36 isomers (in parentheses) are -10.8 (T), -7.4 (D-3d'), -6.1 (S-6), -3.4 (T-h), and -5.6 ppm (D-3d) Despite 12 unusually long CC bonds (1.646 Angstrom at SCF/3-21G), the T form has the lowest energy of all isomers studied and is more stable than T-h by ca. 59 kcal/mol (SCF/3-21G level). The computed delta(He-3) values depend primarily on the numbers of benzene rings present. It is suggested that the He-3 labeling and NMR technique, assisted by the computational results presented, could provide new information concerning the nature of the products arising from Birch reduction and hydrogenation reactions of C-60. [References: 36]