Second-order paramagnetic rhenium(III) complexes: solid-state structure and assignment of the carbon-13 magnetic resonance spectra in solution
Abstract
Single-crystal X-ray diffraction of trans,mer-[ReCl3(PEt2Ph)3] has confirmed the structure derived from 1H and 13C NMR spectroscopy: space group Pbca, a= 15.122(3), b= 20.019(4), c= 21.689(4), Å, z= 8. The carbon-13 NMR spectra of [ReCl3(PEt2Ph)3] and [ReCl3(PPrn2Ph)3] have been assigned on the basis of the known proton-assignments by 13C–1H correlation spectroscopy experiments. The spectra show no couplings between 13C and 13P. The C1 carbon resonances for the aryl groups, unlike the Cα resonances of the alkyl groups, are too broad for detection. The proton relaxation rates T1–1 and T2–1 as well as the linewidths in three different magnetic fields, corresponding to proton frequencies of 250, 400 and 600 MHz, show an increase with field strength.