Solid Me 3Sn(O 2CH): molecular and spin dynamics as viewed by 1H, 13C and 119Sn nuclear magnetic resonance spectroscopy

Abstract

Because of favourable dynamic properties in the solid state, crystalline trimethyltin formate, Me 3Sn(O 2CH), 1, offers quite unique possibilities to probe questions related to molecular dynamics ( 2π 3 Me 3Sn reorientation) and to structural aspects (rigidity of the polymeric backbone, effectively isolated 1H 13C spin pair in the bidentate chain-building formate anion) by 1H, 13C and 119Sn high-resolution solid-state nuclear magnetic resonance (NMR) methods. The combined use of various one- (1D) and two-dimensional (2D) variable-temperature NMR experiments, including consideration of the short-time-cross-polarization (CP) behaviour of the 1H 13C spin pair in 13C-labelled Me 3Sn(O 2 ∗CH), 1 ∗, yields a fairly comprehensive description of the solid-state structure of 1, also in the absence of the single-crystal X-ray structure determination of 1. Taking advantage of the anisotropic polarization transfer within the formate 1H 13C spin pair allows to relate the orientation of the 1H 13C dipolar interaction, i.e. the CH bond direction to the principal axes system of the 13C shielding tensor of the formate 13C from static 13C powder patterns of 1 ∗.