5-Cyanoimino-4-Oxomethylene-Dihydroimidazole and Nitrosative Guanine Deamination. A Theoretical Study of Geometries, Electronic Structures and N-Protonation

Sundeep Rayat and Rainer Glaser*

Department of Chemistry
University of Missouri-Columbia
Columbia, Missouri, 65211 (USA)

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Figure Legends

Figure 1. Structures of the cyanoimines 1 (R = H) and 2 (R = CH₃).
1a: RHF, B3LYP, MP2. 1b: RHF, B3LYP, MP2.
2a: RHF, B3LYP, MP2. 2b: RHF, B3LYP, MP2.

Figure 2. Structures of the cyanoimine 3. Structures with S conformations about the glycosidic C-N bond are shown in the top row and structures with A conformations are shown on the bottom. Relatives energies E_rel and relative Gibbs free energies G_rel values are given in kcal/mol.
3a-Sg: RHF, B3LYP, MP2. 3b-Sg: RHF, B3LYP, MP2.
3a-Sst: RHF, B3LYP, MP2. 3b-Sst: RHF, B3LYP, MP2.
3a-Ag: RHF, B3LYP, MP2. 3b-Ag: RHF, B3LYP, MP2.
3a-Ast, C_s: RHF, B3LYP, MP2. 3b-Ast, C_s: RHF, B3LYP, MP2.

Figure 3. Structures of the cations 4 and 5.
4a, C_s: RHF, B3LYP, MP2. 4a, C₁: B3LYP, MP2.
4b, C_s: RHF, B3LYP, MP2. 4b, C₁: B3LYP, MP2.
5a: RHF, B3LYP, MP2. 5b: RHF, B3LYP, MP2.

Figure 4. Structures of the cations 6 and 7.
6a, C_s: RHF, B3LYP, MP2. 6a, C₁: B3LYP, MP2.
6b, C_s: RHF, B3LYP, MP2. 6b, C₁: RHF, B3LYP, MP2.
7a: RHF, B3LYP, MP2. 7b, C_s: RHF, B3LYP, MP2. 7b, C₁: MP2.

Figure 5. Structures of cations 8 and 9 with synclinal (S) conformations with respect to glycosidic C-N bond and gauche (g) C-O bond conformation.
8a-Sg: RHF, B3LYP, MP2. 8b-Sg: RHF, B3LYP, MP2.
9a-Sg: RHF, B3LYP, MP2. 9b-Sg: RHF, B3LYP, MP2.

Figure 5-2. (SM only) Structures of the cations 8 and 9 with anticlinal (A) conformation with respect to the glycosidic C-N bond and gauche (g) C-O bond conformation.
8a-Ag: RHF, B3LYP, MP2. 8b-Ag: RHF, B3LYP, MP2.
9a-Ag: RHF, B3LYP, MP2. 9b-Ag: RHF, B3LYP, MP2.

Figure 6. Structures of the cations 8 and 9 with synclinal (S) conformation with respect to the glycosidic C-N bond and s-trans (st) C-O bond conformation.
8a-Sst: RHF, B3LYP, MP2. 8b-Sst: RHF, B3LYP, MP2.
9a-Sst: RHF, B3LYP, MP2. 9b-Sst: RHF, B3LYP, MP2.

Figure 6-2. (SM only) Structure of the cation 9 with anticlinal (A) conformation with respect to the glycosidic C-N bond and s-trans (st) C-O bond conformation.
9b-Ast: RHF, B3LYP, MP2.

Figure 7. Structures of the parent carbodiimide 10, of the planar transition state structure of cyanoamine 11, and of the pyramidal structure minimum structures of cyanoamine 12.
10: RHF, B3LYP, MP2.
11: RHF, B3LYP, MP2.
12: RHF, B3LYP, MP2.

Figure 8. Structures of the cyanoimine of formaldehyde, 13, and of the cations 14 and 15 obtained by cyano-N and imino-N protonation.
13: RHF, B3LYP, MP2.
14: RHF, B3LYP, MP2.
15: RHF, B3LYP, MP2.