Kinetic and Thermodynamic acidities of Thiocarbene complexes. Effect of the p-donor group.

MARTIN E. ZOLOFF MICHOFF; DIEGO M. ANDRADA; ALEJANDRO M. GRANADOS; RITA H. DE ROSSI

NEW JOURNAL OF CHEMISTRY

RSC Publishing

Lugar: Londres (Reino Unido) y Montpellier (Francia); Año: 2008 vol. 32 p. 65 - 72

1144-0546

Rate constants for the proton transfer reaction from Fischer thiocarbene complexes (CO)5M=C(SR1)CH3 (M = Cr or W; R1 = n-butyl, isopropyl, tert-butyl, cyclohexyl) to OH
5M=C(SR1)CH3 (M = Cr or W; R1 = n-butyl, isopropyl, tert-butyl, cyclohexyl) to OH
and various primary and secondary amines were determined in 50% acetonitrile–50% water at 25 1C. These measurements allowed the determination of the thermodynamic and kinetic acidities for these substrates. The results obtained show that there is a slight effect of the substituent on the thermodynamic acidity, which is governed by its hydrophobicity; whereas the effect on the kinetic acidity is more noticeable and is due to the steric effect of the substituent.1C. These measurements allowed the determination of the thermodynamic and kinetic acidities for these substrates. The results obtained show that there is a slight effect of the substituent on the thermodynamic acidity, which is governed by its hydrophobicity; whereas the effect on the kinetic acidity is more noticeable and is due to the steric effect of the substituent.