The understanding of isomerization processses in labile divalent 3d-metal complexes are still open to many questions. Though dynamic NMR spectroscopy in the conditions of VP and VT is a well-known tool to investigate rather inert complexes, it has also been successfully employed in stereochemical studies of labile cobalt (II) complexes in solution. Providing that the electron spin relaxation is at its optimum, NMR spectroscopy can be used to investigate equilibria and kinetics of isomeric forms of paramagnetic complexes in solution. It has been established that the dipolar pseudocontact component is the predominant factor for paramagnetic NMR chemical shift in Co(II) ( 4 T1g) coordination compounds. The observed chemical shifts are important in respect to the broadening of the resonance lines, leading to well resolved spectra. Octahedral cobalt (II) complexes usually undergo substitution reactions according to dissociative pathways. By analogy, two isomerization patterns involving only single step dissociative mechanisms (pentacoordinated trigonal bipyramidal intermediate) can be suggested: Monodentate dissociative mechanism: dissociative Pic bound/free ligand exchange may proceed with isomerization, or not. Bidentate bond-rupture mechanism: it involves the breaking of the weakest Co–O bond with the TUF ligand (closest to the CF3 withdrawing group). The reformation of the bond may lead to isomerization, or not. This mechanism is not purely dissociative, since TUF remains partially bonded to the metal centre in the intermediate. Hence this is a bond-rupture mechanism.figureIt can be shown that among the ten possible isomerization reactions, only six can directly occur for a single step dissociative mechanism. These six possible routes are shown. Among those six routes, four (IIIV, III, IIV, IIIV & IIIV) are common for both isomerization patterns suggested above. However the route IIII can occur for the monodentate dissociative mechanism but not for the bidentate bond-rupture mechanism. In contrary, the route IIIIV can occur for the bidentate case but not for the monodentate one. Over the whole range of temperature studied, a very good agreement between experimental and fitted data was obtained when the route IIII was neglected (see the excellent agreement between experimental and calculated spectra), while neglecting IIIIV did not lead to an acceptable fit of the spectra. On the basis on these observations, the bond rupture mechanism is suggested for the isomerization of compound 1 in CD2Cl2. The five possible isomers of the octahedral adduct [Co(TUF)2(Pic)2] were observed and identified by 19 F NMR, in CD2Cl2. The thermodynamic parameters (∆H°, ∆S°) between all the isomers for the isomerization equilibria were determined. The lineshape analysis of the spectra allowed to identify the isomerization pathways. Among the two possible single step dissociative mechanisms, the bidentate single bond rupture gave the most satisfying fit over the whole temperature range.