Messanae Universitas Studiorum

Velocità e meccanismo di sostituzione dello ione cloro del $trans-[Pt(PET)_3(o-tolile) \ Cl]$ con ammine: influenza della basicità e dello ingombro sterico delle ammine sulla reattività verso l'intermedio di reazione

Minniti, Domenico and Ricevuto, Vittorio and Romeo, Raffaello and Trozzi, M. (1972) Velocità e meccanismo di sostituzione dello ione cloro del $trans-[Pt(PET)_3(o-tolile) \ Cl]$ con ammine: influenza della basicità e dello ingombro sterico delle ammine sulla reattività verso l'intermedio di reazione. Accademia Peloritana dei Pericolanti Classe FF.MM.NN., 52. pp. 43-58.

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    Abstract

    The replacement of chloride ion in the $trans-[Pt (PEt_3)_2 (o-tolyl) Cl]$ by substituted pyridines has been studied in the presence of LiCl (0,005 M) in methanol at 30°. The pseudo first-order rate constants for approach to equilibrium conform to the equation:
    $k_o_b_s=\frac{ k_1 [am] + k_4 k_2/k_3[Cl^-]} {k_2/k_3 [Cl^- + [am]}$
    where $k_1$ and $k_4$ represent the solvolytic rates of generation of the intermediate $trans-[Pt (PEt_3)_2 (o-tolyl)MeOH]^+$ from the starting chloro complex and the pyridino derivate respectively. $k_2/k_3$ represents the efficiency with which the $Cl^-$ captures the intermediate in competion with the amines and is a measure of the reagent reactivity too. A comparison of the relative $k_2/k_3$ values of the amines shows a lack of correlation of basicity and reactivity and suggests that steric hindrance plays an appreciable role in determining the nucleophilicity. The bulkiness of the reagent determines also the values of the equilibrium constants which have been calculated from kinetic parameters and checked by means of direct spectrophotometric method.

    Item Type: Article
    Subjects: M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali > 1972
    M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Giuridiche, Economiche e Politiche > 1972
    Divisions: UNSPECIFIED
    Depositing User: Dr M P
    Date Deposited: 26 Oct 2012 10:20
    Last Modified: 22 Jan 2013 13:14
    URI: http://cab.unime.it/mus/id/eprint/1497

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