Untitled

Structure and relative energies of regioisomers and valence isomers of C60 adducts. HF and DFT study

“…We shall notice, that bis-adducts of both above-discussed addends cis-1-C 60 (NCOOMe) 2 14 and cis-1-C 60 (NR*) 2 13 have more stable [6,6]-open form in comparison with [6,6]-closed one. Local minima searching problems can be related to local minima searching for [5,6]-closed structures.…”

“…The coordinated change of relative energies of the open and closed isomers Nbridged mono-and bis-adducts is revealed. We have demonstrated that closed form of compounds C 60 NR 2,3 and cis-1-C 60 (NR) 2 [9,10] (R ϭ Me, Ph) 6,6 is more stable, and for compounds C 60 NR 6,7 and cis-1-C 60 (NR) 2 [13,14] (R ϭ COOMe, R*-the nitropyrimidine) [5,6]-open and cis-1 [6,6]-open form is more stable, that corresponds to experiment. For compounds cis-1-C 60 (NH) 2 8 the closed form is by 5.9 kcal/mol more stable than the open form, for 13 open form is more stable than the closed one by 4.1 kcal/mol.…”

“…The [5,6]-opened form of 2 and 3 rearranges in more stable [6,6]-closed form [8,13]. Thermal transition of [5,6]-open forms of compound 6 into [6,6]-closed ones is not observed [14]. Later it will be shown, that conjugation and direct polar conjugation of substituents R with fullerene shell C60 -n N -R is the reason of stabilization of bis- [6,6]-open forms of N-bridged compounds C 60 (NR) 2 .…”

“…The cis-1 C 60 (NH) 2 8 is more stable in the closed form and cis-1 homodiazafullerenes C 60 (NCOOR) 2 14 and C 60 (NR*) 2 13, where R* ϭ C 4 H 2 N 3 O is nitropyrimidine group are more stable in the open form [11,20]. We have investigated a series of closed and open valence isomeris of cis-1 C 60 (NR) 2 8 -14 at the purposeful variation of R, allowing to reveal an originality of R* (Table I, Fig.…”

“…1). Thermal, photochemical, electrochemical, and catalytic isomerization of [5,6]open fulleroids into [6,6]-closed methanofullerenes [3][4][5]19] is well-studied, while isomerization of [5,6]-open aziridinofulleroids or [6,6]-closed aziridinofullerenes is poorly investigated [7,14]. The [5,6]-closed form is used as intermediate structure in these rearrangements [3][4][5][6]19].…”