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.

Graphical Abstract

Keywords:

• Palladium
• Platinum
• Trinuclear
• C₃-Symmetric
• Star-shaped

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (Grant No. NRF-2020R1F1A1067303). This study was also supported by 2021 Academic Research Support Program in Gangneung-Wonju National University.