¹H,¹¹⁷ Sn J‐HMBC spectroscopy as a tool for the determination of long‐range <i>ⁿJ</i> (¹H,¹¹⁷Sn) coupling constants in the investigation of intramolecular donor–acceptor interaction in [2‐(<i>N,N</i>‐dimethylaminomethyl)phenyl]stannanes

Abstract

Abstract 1 H, 117 Sn J‐HMBC spectroscopy was implemented as a tool for the determination of long range n J ( 1 H, 117 Sn) coupling constants of [2‐( N,N ‐dimethylaminomethyl)phenyl]stannanes, ArR 1 R 2 R 3 Sn or Ar 2 R 1 R 2 Sn, where R 1 , R 2 and R 3 are Ph or n ‐Bu, and/or Cl or Br. It is demonstrated that coupling constants which are too small to be measured from multiplet splittings in the 1 H or 117 Sn spectra can be measured from the development of the sine modulation of the intensity of the 1 H, 117 Sn HMBC correlation peaks as a function of the incremented preparation time of the 1 H, 117 Sn HMBC pulse sequence. It is examined whether such couplings can be used as straightforward indicators for the existence of intramolecular nitrogen–tin interactions. While some coupling constants are shown to depend on the strength of the above‐mentioned interaction, it is also demonstrated that 6 J ( 1 H, 117 Sn) coupling constants between the N ‐methyl groups and the tin nucleus can be observed even in structures where no nitrogen–tin interactions are possible. Copyright © 2001 John Wiley &amp; Sons, Ltd.