Masashi Hatanaka

Ab initio study on quartet states of non‐Kekulé‐type molecules 1,3,5‐trimethylenebenzene and 1,3,5‐triaminobenzene trication

The electronic structures of non‐Kekule‐type isoelectronic molecules 1,3,5‐trimethylenebenzene (TMB) and 1,3,5‐triaminobenzene trication (TAB3+) having a threefold axis are discussed with the ab initio molecular orbital (MO) method. The quartet state with a D3h geometry is predicted to be the ground state of TMB and TAB3+. According to the Jahn–Teller theorem, the doublet 2E‘ states of TMB and TAB3+ are subject to the first order distortions which remove the degeneracy. The quartet–doublet energy splittings are calculated for these non‐Kekule‐type molecules at the second order Mo/ller–Plesset (MP2) perturbation level of theory. In TMB the 4A2‘ state with a planar D3h geometry is predicted to lie well below the 2A2 state with a planar C2v geometry in which one of the methylene groups has a longer C–C bridge bond connecting with the benzene ring. Moreover, in TAB3+ the 4A2‘ state with a planar D3h geometry also lies well below the 2A2 state. The 2A2–2B1 energy splittings on the pseudorotation potential surf...

Quartet states of non-Kekulé molecules 1,3,5-trimethylenebenzene and 1,3,5-triaminobenzene trication

Abstract The electronic structures of non-Kekule isoelectronic molecules 1,3,5-trimethylenebenzene (TMB) and 1,3,5-triaminobenzene trication (TAB3+ are discussed by means of the ab initio molecular orbital (MO) method in the unrestricted Hartree—Fock scheme. In TMB the quartet state with planar D3h geometry is predicted to lie 26 kcal/mol below the lowest doublet state with a planar C2v geometry in which one of the methylene groups has a longer CC bridge bond connecting the phenyl ring. Moreover, in TAB3+ the quartet state with planar D3h geometry also lies 17 kcal/mol below the lowest doublet state with an orthogonal geometry where one of the amino groups is twisted out of the molecular plane. These quartet ground states result from the nearly threefold-degenerate orbitals consisting of the nonbonding MOs.

Molecular Orbital Study on Quartet Molecules with Trigonal Axis of Symmetry

Abstract The ESR spectrum of the randomly oriented cationic triradical of 1,3,5-tris(diphenylamino)benzene (TDAB) is shown to agree well with the theoretical prediction of a quartet (5 = 3/2) molecule. The electronic structures of non-Kekule-type isoelectronic molecules 1,3,5-trimethylenebenzene (TMB) and 1,3,5-triamino-benzene trication (TAB3+) are discussed by means of the ab initio molecular orbital (MO) method in the unrestricted Hartree-Fock scheme. In TMB the quartet state with planar D3h geometry is predicted to lie 26. 1 kcal/mol below the lowest doublet state with a planar C2V geometry in which one of the methylene groups has a longer C-Cbridge bond connecting the phenyl ring. Moreover, in TAB3+ the quartet state with planar D3h also lies 16. 9 kcal/mol below the lowest doublet state with an orthogonal geometry where one of the amino groups is twisted out of the molecular plane. These quartet ground states result from the nearly threefold-degenerate orbitals consisting of the nonbonding MOs. In a...

Study on magnetic properties of triaminobenzenes toward charge-transfer organic ferromagnets

Summary form only given. We have shown that the ESR spectrum of the cationic triradical of TDAB in CH2Cl2 matrix agrees well with the theoretical prediction for a quartet (S = 3/2) molecule.1 Our ab initio MO calculatiom at the MJP2 perturbation level have also shown that the quartet state of the cationic triradical of 1,3,5 triaminobenzene lies 12 kcal/mol below the doublet states. In order to stabilize these cationic states, we prepared TDAAB and characterized its C1O/sub 4/Bf/sub 4/ and PF/sub 6/ 1:1 salts. A theoretical strategy to obtain this type of organic ferromagnets and results of ESR and static magnetic-susceptibility measurements of these charge-transfer solids are presented.

High-spin state instability in nitroxide triradical coupled through m-phenylene

Abstract The electronic structure of 2-methoxy-1,3,5-benzenetriyltris (N-hydronitroxide) (MBTN) is discussed with the ab initio molecular orbital method at the second-order M0ller-Plesset perturbation level of theory. The result explains why high-spin states are unstable in some hindered nitroxide di-and triradicals coupled through m-phenylene.

Molecular orbital study on cationic states of triphenylene and 1,3,5-tris(diphenylamino)benzene as a design of charge-transfer organic ferromagnet

Abstract For the design of charge-transfer organic ferromagnets, the electronic structures of the neutral, mono-, di- and trications states of triphenylene and 1,3,5-tris(diphenylamino)benzene (TDAB) are studied with the semiempirical PM3-MO method. It is shown that the high-spin states of the di- and trications of TDAB lie below the corresponding low-spin states.