H-1, Sn-117 J-HMBC spectroscopy as a tool for the determination of long-range (n)J(H-1, Sn-117) coupling constants in the investigation of intramolecular donor-acceptor interaction in [2-(N,N-dimethylaminomethyl)phenyl]stannanes

摘要

H-1, Sn-117 J-HMBC spectroscopy was implemented as a tool for the determination of long range (n)J(H-1, Sn-117) coupling constants of [2-(N,N-dimethylaminomethyl)phenyl]stannanes, ArR1R2R3Sn or Ar2R1R2Sn, 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 H-1 or Sn-117 spectra can be measured from the development of the sine modulation of the intensity of the H-1, Sn-117 HMBC correlation peaks as a function of the incremented preparation time of the H-1,Sn-117 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(H-1,Sn-117) 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 (C) 2001 John Wiley Sons, Ltd. [References: 15]