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 C_α 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.