J. Am. Chem. Soc. 1996, 118, 8077-8084
8077
Nature of the Intramolecular Se‚‚‚N Nonbonded Interaction of 2-Selenobenzylamine Derivatives. An Experimental Evaluation by 1H, 77Se, and 15N NMR Spectroscopy Michio Iwaoka and Shuji Tomoda* Contribution from the Department of Chemistry, College of Arts and Sciences, The UniVersity of Tokyo, Komaba, Meguro-ku, Tokyo 153, Japan ReceiVed October 2, 1995X
Abstract: 1H NMR analysis of seven 2-selenobenzylamine derivatives (ArSeX, 1-7) has revealed the existence of attractive nonbonded interaction between the divalent selenium and an unsymmetric amino nitrogen, whose strength significantly depends on the relative electrophilic reactivity of the selenium moiety. In the intermediate cases (5, X ) CN; 6, X ) SPh), the dissociation energy of the Se‚‚‚N nonbonded interaction was evaluated as 12.4 and 10.8 kcal/mol, respectively, by variable-temperature 1H NMR spectral simulations. The corresponding values were roughly estimated as >18.8 kcal/mol for the strong cases (2, X ) Br; 3, X ) Cl; 4, X ) OAc) and 320 >320 >320
5: X ) CN
3.68 3.75, 3.54c 3.73 3.82, 3.62d
6: X ) SPh 1: X ) SeAr 7: X ) Me
3.72 3.67
241 (13.8) 217 (13.0)
