539848-02-7Relevant articles and documents
Addition reactions of η3-allenyl/propargyl and η3-trimethylenemethane complexes of platinum and palladium
Dunsizer, R. Todd,Marsico, Vera M.,Plantevin, Véronique,Wojcicki, Andrew
, p. 279 - 290 (2008/10/08)
A study of reactions of η3-allenyl/propargyl complexes of platinum and palladium with transition-metal hydrides and secondary amines and of η3-trimethylenemethane (η3-TMM) complexes of platinum with unsaturated electrophiles is presented. The reaction of [(PPh3)2Pt(η3-CH2CCPh)]OTf (1aOTf) with Cp(CO)2RuH affords the η3-allyl complex [(PPh3)2Pt(η3-CH2CHC(Ph)Ru (CO)2Cp)]OTf, whereas that of 1aOTf with Cp2Zr(Cl)H furnishes [(PPh3)2Pt(η3-CH2CHCHPh)]OTf (3OTf). The source of the CHPh hydrogen in the latter reaction appears to be adventitious H2O, as evidenced by the formation of [(PPh3)2Pt(η3-CH2CHCDPh)]OTf when 1aOTf was treated with D2O and Cp2Zr(Cl)H. Possible mechanisms of formation of 3OTf are presented. The secondary amines R2NH (R=i-Pr or sec-Bu) react with 1aOTs and its palladium analog, 1bOTs, to give the η3-(2-aminoallyl) complexes [(PPh3)2M(η3-CH2C(NR 2)CHPh)]OTs (M=Pt, Pd). Competition studies reveal the following order of reactivity, attributed to steric effects: Et2NH (74 and 38)>(i-Pr)2NH (3.5 and 5)>(sec-Bu)2NH (1) for 1aOTs and 1bOTs, respectively. The complex 1aOTs reacts much faster with Et2NH than with EtOH. Reactions of the η3-TMM complexes (PPh3)2Pt(η3-CH2C(C(CO 2Me)2)CHR) (R=Me (7), Ph (8)) with the very strong electrophiles/polarophiles TCNE and p-toluenesulfonyl isocyanate (TSI) lead to [3+2] cycloaddition of the electrophile to the η3-TMM ligand, and the resulting cycloadduct is isolated either free (with TSI) or complexed as an alkene to the metal (with TCNE). The weaker electrophiles diethyl fumarate and fumaronitrile (E) react with 7 or 8 to furnish (PPh3)2PtE and a [3+3] coupling product of the η3-TMM ligand. All new compounds were characterized by a combination of elemental analysis, mass spectrometry and 1H, 13C{1H} and 31P{1H} NMR spectroscopy.