1,2 Hydrogen shifts in thioformaldehyde (H2CS), phosphazene (HNPH) and diphosphene (HPPH): In-plane versus out-of-plane migration
✍ Scribed by Minh Tho Nguyen; Tae-Kyu Ha
- Book ID
- 103028476
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 590 KB
- Volume
- 158
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
HzPN and H2PL, using ab initio MO methods. Geometries were determined at the MP2/6-31G** level with relative energies estimated by single-point calculations at the MP4/ 6-311+ +G(df, p) level, including zero-point corrections. For HzCS the reason for previous conflicting reports is explained; it is confirmed that the 1,2 shift takes place in the molecular plane. In HLPN, out-of-plane transfer is marginally favoured over inplane, suggesting that the latter becomes effective in substituted phosphazenes. In contrast, out-of-plane transfer predominates in H2Pz. These results suggest that the migrating hydrogen behaves as a hydride at the transition states in H,CS and H>PN but as a proton in H2PI. Stabilizing interactions between the migrating proton and the II: electron of the double bond favours an out-ofplane migration in the latter case. Relative energies are estimated as follows (in kcal/mol): H,C=S (O.O)-+TT (78.6)+trans-HC-SH (47.6); HN=PH (0.0) +TS (81.8)-~+N=PHL (39.0) and HP=PH (0.0) +TS (51.4) +P-PH, (25.X).