1352815-21-4Relevant articles and documents
Kinetics of the reaction of arylethanediylidene-bis-dithiocarbazonoate Ni complexes with morpholine in benzene: Substituent and temperature effects
Shehata, Aziza K.,Fathalla, Magda F.,Header, Heba M. A.,Hamed, Ezzat A.
, p. 27 - 40 (2012)
[1-Arylethanediylidene-bis(methyl dithiocarbazonoate) NN′SS′ (-2)]Ni(II) complexes were prepared by condensation of arylglyoxals with methyl dithiocarbazoate to give the corresponding hydrazonoates. The chelation of nickel(II) with these hydrazonoates gave square planar Ni complexes. The k 3 values for the substitution of -SCH3 close to the aryl group with morpholine (Mo) in benzene were found to increase steadily (20-35°C) followed by a sudden drop after 35°C. A continuous decrease in k3 values was observed by further elevation in the temperature. The Arrhenius plot showed a convex curve at the whole temperatures 20-55°C, and negative ΔH# values for the reactions were obtained at 40-55°C. The Hammett plots at the temperature ranges 20-35° and 40-55°C exhibited good straight lines with ρ values of 1.44-0.73 and 1.18-1.25, respectively. The proposed mechanism is a nucleophilic aromatic substitution-like, in which the rate-determining step is the proton transfer process in the temperature range 20-35°C whereas the mechanism in the range 40-55°C passes through the attack of Mo on the carbon carrying the SCH 3 group followed by the addition of the second Mo molecule on Ni to form an intermediate, which undergoes elimination of Mo and CH3SH to give a monosubstitution complex.
