The effect of the halide on the Lewis acidity of organotin halides (original) (raw)

1990, Journal of Organometallic Chemistry

Thermodynamic parameters for adduct formation by R,SnX,_,, where R is methyl, ethyl, or butyl, and X is Cl, Br, or I, with tributylphosphine (TBP) in benzene and chlorobenzene solvents are reported. These data are combined with previously reported data for the same systems with triphenylphosphine oxide (TPPO). The enthalpies of adduct formation generally increase in the order Cl < Br < I thus producing a reversal of the acid-strengthening effects due to substitution of more electronegative elements_ Equilibrium constants, however, increase in the order I < Br < Cl, indicating a dominance of the entropy term for formation of these organotin halide adducts with TBP and TPPO. 0022-328X/90/%03.50 0 1990 -Elsevier Sequoia S.A.