Fairly Strong Ferromagnetic Interactions between Imino Nitroxide Ligands through a Diamagnetic CuI Ion in [CuI(im-mepy)2](PF6)
✍ Scribed by Prof. Hiroki Oshio; Takashi Watanabe; Akihiro Ohto; Prof. Tasuku Ito; Prof. Umpei Nagashima
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 264 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0044-8249
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✦ Synopsis
By which mechanism does this rearrangement occur? Two possibilities are conceivable: either a [1,2]-H migration or a C-C bond shift (Fig. ). For both alternative pathways the saddle points were located and characterized by analysis of the force constant matrix as unambiguous transition structures (one negative eigenvalue). The saddle point associated with the [1,2]-H migration, TSlS, is very high in energy (88.5 kcalmol-' higher than IS); in comparison that associated with the C-C bond shift, TS2S, is clearly more favorable (23.5 kcalmol-' higher in energy than 2s). As is clear from Table 1, TSlT is also much higher in energy than TS2T. The quantitative energy differences may be somewhat different at a higher level of theory, but the qualitative result that the C-C bond shift is clearly favored over H migration should remain unchanged. This result confirms the experimental findings of Eaton and Whitec3] for the 9-phenylsubstituted derivative of 1 and 2.
Because of the extremely strained structure, the double bond character of 1 is significantly reduced, and 1s is only a formal olefin. As a result of the destabilization of lS, the isomeric 2S becomes similar in energy, which is reflected in the reversible rearrangement 1 =S 2 observed experimentally. This rearrangement occurs by a C-C bond shift with a relatively low activation barrier.