We have studied the effect of pressure on the configurational inversion reaction at the metal centre of the chiral tris-(cyclic O,O'1(R),2(R)-dimethylethylene dithiophosphato) chromium(III) complexes, Λ(-)589Cr[(R,R)bdtp]3 and Δ(+)589Cr[(R,R)bdtp]3, in solutions of different solvents. We have observed positive or negative Cotton effects, assigned to the 4A2→4T2 transition of the metal ion in the visible region, and their evolution on increasing pressure. At equilibrium and at room conditions one observes a prevalence of the Δ-(R,R)(R,R)(R,R) diastereoisomer in CHCl3 or CH2Cl2 and of the Λ- one in THF. On increasing the pressure a change in the inversion equilibrium occurs, producing an increase in the concentration of the Λ-(R,R)(R,R)(R,R) form in all solvents.
Configurational equilibrium and CD spectra under pressure of chiral octahedral complexes: Λ- and Δ-Cr[(-)(R,R)bdtp]3
BENEDETTI, MICHELE;
1999-01-01
Abstract
We have studied the effect of pressure on the configurational inversion reaction at the metal centre of the chiral tris-(cyclic O,O'1(R),2(R)-dimethylethylene dithiophosphato) chromium(III) complexes, Λ(-)589Cr[(R,R)bdtp]3 and Δ(+)589Cr[(R,R)bdtp]3, in solutions of different solvents. We have observed positive or negative Cotton effects, assigned to the 4A2→4T2 transition of the metal ion in the visible region, and their evolution on increasing pressure. At equilibrium and at room conditions one observes a prevalence of the Δ-(R,R)(R,R)(R,R) diastereoisomer in CHCl3 or CH2Cl2 and of the Λ- one in THF. On increasing the pressure a change in the inversion equilibrium occurs, producing an increase in the concentration of the Λ-(R,R)(R,R)(R,R) form in all solvents.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
