14N NMR of amminecobalt(III) compounds

Directly detected ammine 14N NMR chemical shifts of 20 amminecobalt(III) compounds are reported. The coordination shifts, δCS = δcoord − δfree, are in all cases negative and range from −4.4 ppm for the trans ammine ligand in [Co(NH3)5(CH3)]2+ to −73.6 ppm for the trans ammine ligand in [Co(NH3)5(F)]2+. Among the ligands studied, the NO2− ligand is unique in that it exerts a significant cis influence. The regularity in trans or cis influences upon the ammine nitrogen chemical shifts provides a basis for assignments in cases where this cannot be deduced from intensity ratios.