Star-shaped Pd(II) and Pt(II) complexes containing C3-symmetric conjugated thiophenes: Synthesis, characterization, and chemical reactions with organic unsaturated molecules

Abstract

Triple oxidative addition reactions of [M0(styrene)(PMe3)2] (M = Pd/Pt) with C3-symmetric star-shaped molecules containing 1-, 3-, and 5-thiophene-substituted benzene, in 1:0.3 ratio, afforded new Pd(II) and Pt(II) trinuclear complexes in suitable yields. Analogous trinuclear complexes were formed by similar reactions of thiophenyl halide derivatives containing triazine or triphenylamine cores. Alternatively, a trinuclear Pd(II) complex was obtained by oxidative addition of a Pd(0) complex (synthesized from allyl(cyclopentadienyl) palladium(II), [(η5-C5H5)Pd(η3-C3H5)] with PEt3. Sonogashira-type coupling between trinuclear Pt(II) halides (containing C3-symmetric conjugated thiophenes) and alkynes, in the presence of cuprous halide and diethylamine, afforded alkynyl-containing trinuclear Pt(II) complexes with extended π-conjugation. Insertion reactions of organic isocyanides (CN-R) with trinuclear Pd(II) complexes yielded trinuclear Pd(II) imidoyl complexes by insertion of CN-R into Pd-carbon (thiophene) bonds. Reactions of trinuclear Pt(II) halides with Ag(OCOCF3) and NaN3 formed pseudohalogen-containing Pt(II) complexes.