Linkage isomerism in cobalt(III) complexes

Asymmetric Synthesis of Coordination Compounds: Back to the Roots. Diastereoselective Synthesis of Simple Platinum(IV) Complexes

“…The signals of the CH protons of the minor species (D-[Pt{(S)-pn} 3 ] 4 ) are split over a larger range (3.79 ± 3.87 ppm). This might be due to the appearance of several conformers of similar energy, as it has been described for analogous Co III complexes [13]. We assume, in accordance with the cited literature, that the conformation in the major species is fixed in an all equatorial position for the CH 3 group [14] [15].…”

“…Since Pt IV , as low-spin 5d 6 system, forms exclusively diamagnetic complexes, NMR spectroscopy is the method of choice for the elucidation of the configuration of the coordination species. We exploited the spectra of all nuclei in the complex [Pt(pn) 3 ] 4 , i.e., 1 H, 13 C, 15 N, and 195 Pt. Except for 15 N, where enriched samples were prepared, all nuclei were studied in their natural abundances.…”

“…Except for 15 N, where enriched samples were prepared, all nuclei were studied in their natural abundances. 13 C-NMR Spectroscopy. The most-straightforward results are obtained from the 1 Hdecoupled 13 C-NMR spectra of [Pt(pn) 3 ] 4 .…”

Intrinsic and Environmental Effects on the Kinetic and Thermodynamics of Linkage Isomerization in Nitritopentaamminecobalt(III) Complex

“…The fast isomerization of nitrite ion bound to pentaamminecobalt(III) complex is the first known example of linkage isomerism in coordination chemistry. − This reaction has been so extensively studied by experimentalists that it is now considered in all inorganic chemistry textbooks as the prototype of this class of reactions. , Furthermore, a number of similar complexes, characterized by different metal centers and ligands, undergo a similar isomerization. − The kinetics and the thermodynamics of the spontaneous isomerization of the nitritopentaamminecobalt(III) complex, [Co(NH 3 ) 5 ONO] 2+ , in the corresponding nitro complex, [Co(NH 3 ) 5 NO 2 ] 2+ , have been studied both in solution and in the solid state. − This reaction was proved to be intramolecular by using different experimental techniques. In fact, the kinetics in aqueous solution is independent of the NO 2 - concentration added 11 and 18 O tracer techniques showed that neither the inner Co−O or the outer NO oxygen of the nitrito complexes exchange with solvent during the isomerization .…”

“…4,5 Furthermore, a number of similar complexes, characterized by different metal centers and ligands, undergo a similar isomerization. [6][7][8][9] The kinetics and the thermodynamics of the spontaneous isomerization of the nitritopentaamminecobalt(III) complex, [Co(NH 3 ) 5 ONO] 2+ , in the corresponding nitro complex, [Co(NH 3 ) 5 NO 2 ] 2+ , have been studied both in solution and in the solid state. [10][11][12][13][14][15][16][17] This reaction was proved to be intramolecular by using different experimental techniques.…”