The kinetics of the reaction ~is-[Pt(Me~SO)~C+1 a~m1 - cis-[Pt(Me,SO)(am)CIz] + MezSO (Me2S0 = dimethyl sulfoxide; am = pyridine, a substituted pyridine, or a diazine) have been studied in 1,2-dimethoxyethane at 25 OC. The second-order rate constant, kZ, is sensithe to the basicity of the entering nucleophile, a (the slope of the plot of log k2 against pK, of amH+) = 0.41, and to steric hindrance. These reactivity relationships are compared to those for the corresponding chelated disulfoxide complexes [Pt(meso-pse)C12] and [Pt(rac-pse)C12] (pse = 1,2-bis(phenylsulfinyl)ethane). The displacement of the monodentate sulfoxide is some 10’ times more facile than ring opening and slightly less sensitive to steric hindrance than the less congested meso-disulfoxide isomer.
Kinetics of Displacement of Dimethyl Sulfoxide fromcis-Dichlorobis(dimethy1 sulfoxide)platinum(II) by Amines in Dimethoxyethane
CANOVESE, Luciano;
1981-01-01
Abstract
The kinetics of the reaction ~is-[Pt(Me~SO)~C+1 a~m1 - cis-[Pt(Me,SO)(am)CIz] + MezSO (Me2S0 = dimethyl sulfoxide; am = pyridine, a substituted pyridine, or a diazine) have been studied in 1,2-dimethoxyethane at 25 OC. The second-order rate constant, kZ, is sensithe to the basicity of the entering nucleophile, a (the slope of the plot of log k2 against pK, of amH+) = 0.41, and to steric hindrance. These reactivity relationships are compared to those for the corresponding chelated disulfoxide complexes [Pt(meso-pse)C12] and [Pt(rac-pse)C12] (pse = 1,2-bis(phenylsulfinyl)ethane). The displacement of the monodentate sulfoxide is some 10’ times more facile than ring opening and slightly less sensitive to steric hindrance than the less congested meso-disulfoxide isomer.
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