Complexes of Oxygenated trans-Azoalkanes and Tetracyanoethylene. The Interaction of π Oxygen Dipoles with an Electron Poor Alkene
| Autor: | Melinda L. Greer, Silas C. Blackstock |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | The Journal of Organic Chemistry. 61:7895-7903 |
| ISSN: | 1520-6904 0022-3263 |
| DOI: | 10.1021/jo960998+ |
| Popis: | The N-oxide and N,N‘-dioxide (1ao and 1ado) of trans-1,1‘-azonorbornane (1) associate with TCNE in solution and in the solid state. The solution complexes are characterized by charge-transfer optical absorptions at λm 364 and 540 nm in CH2Cl2 for 1ao/TCNE and 1ado/TCNE, respectively. These complexes are weakly bound, with Kf values of 0.5−3.0 M-1. Crystals of (1ao)2/TCNE and 1ado/TCNE are isolable, and their structures have been determined by X-ray diffraction. Local donor−acceptor (DA) interactions between the π dipolar donors and the electron poor TCNE are found. Crystals of (1ao)2/TCNE are composed of discrete D−A−D triads in which the 1ao oxygen approaches one of the olefinic C atoms (C1, 2.86 A) of TCNE more closely than the other (C2, 3.07 A). The O−C1−C2 angle is 87°, and the azooxide molecular plane lies perpendicular to the molecular plane of TCNE. 1ado/TCNE crystals are composed of extended −D−A−D−A− strands in which both oxygen poles of the azodioxide simultaneously interact with alternate TCNE... |
| Databáze: | OpenAIRE |
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