Untersuchungen der kernmagnetischen Resonanz von Phosphorverbindungen XXIV

Abstract

Solvent effects of 31P nuclear magnetic resonance of white phosphorus in n-paraffins, substituted and cyclic paraffins, as well as in benzene, and some amines are discussed. The largest chemical shifts were caused on the one hand by dispersion interactions of dissolved phosphorus and solvent molecules and on the other hand by interaction of different phosphorus molecules; the latter influence may shift the resonance signal of white phosphorus about 35 ppm towards higher field relative to solid white phosphorus. Specific interactions between dissolved phosphorus and halogen atoms increased in the series Cl, Br, I. Phosphorus acted as an electron donor. Electron acceptor properties in amines as solvents were not found. Shifts towards lower field in the order of magnitude of 1 ppm were caused by highly polar solvents (Stark effect). By comparing dilute solutions of phosphorus in 1,3-cyclohexadiene and benzene, respectively, the influence of the diamagnetic anisotropy on the resonance of phosphorus could be estimated to result in a shift of about 1 ppm towards higher field, whereby the different dispersion interactions, were taken into account.