Reaction of [PtCl(.eta.2-CH2:CHAr)(tmeda)](ClO4) (1) [Ar = C6H5 (1a), 4-CH3OC6H4 (1b), 3-NO2C6H4 (1c); tmeda = N,N,N',N'-tetramethylethylenediamine] with triethylamine, or even with inorg. carbonate, leads to the abstraction of a vinylic proton and formation of the (alkenyl)platinum species [PtCl{(E)-CH:CHAr}(tmeda)] (2) in high yield. The initially formed (E) isomer, in soln. of chlorinated solvents, partly isomerizes into the (Z) form [equil. ratio (E)/(Z) 4:1]; the isomerization reaction is rather slow and is catalyzed by visible light. The nature of the Ph substituent (electron donor OMe or electron-withdrawing NO2 group) does not appear to affect the rate of deprotonation. The nature and stereochem. of the formed (alkenyl)platinum species has been elucidated through 1D and 2D 1H and 13C NMR spectroscopy.
Vinylic deprotonation in the coordination sphere of platinum(II): Regioselective formation of alkenyl complexes.
FANIZZI, Francesco Paolo;
2004-01-01
Abstract
Reaction of [PtCl(.eta.2-CH2:CHAr)(tmeda)](ClO4) (1) [Ar = C6H5 (1a), 4-CH3OC6H4 (1b), 3-NO2C6H4 (1c); tmeda = N,N,N',N'-tetramethylethylenediamine] with triethylamine, or even with inorg. carbonate, leads to the abstraction of a vinylic proton and formation of the (alkenyl)platinum species [PtCl{(E)-CH:CHAr}(tmeda)] (2) in high yield. The initially formed (E) isomer, in soln. of chlorinated solvents, partly isomerizes into the (Z) form [equil. ratio (E)/(Z) 4:1]; the isomerization reaction is rather slow and is catalyzed by visible light. The nature of the Ph substituent (electron donor OMe or electron-withdrawing NO2 group) does not appear to affect the rate of deprotonation. The nature and stereochem. of the formed (alkenyl)platinum species has been elucidated through 1D and 2D 1H and 13C NMR spectroscopy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
