σ-Thienyl complexes of palladium(II), trans-PdBr(C4H4-nBrn-1S-C)(PPh3)2 (n = 1–4), from oxidative addition of bromothiophenes to Pd(PPh3)4. X-ray structural identification of key intermediates of catalytic debromination of 2-bromothiophene and tetrabromothiophene

Catalytic Dehalogenation of Highly Chlorinated Benzenes and Aroclors Using PdCl2(dppf) and NaBH4: Efficiency, Selectivity, and Base Support

“…The ability for [Pd 0 (dppf)] to undergo oxidative addition with aryl halides has been established . We have also isolated and structurally characterized similar oxidative addition products . The significantly higher reactivity of polychlorobenzene compared to that of the lower chlorobenzenes in our catalytic mixtures is also consistent with this proposed key step.…”

Ferrocene End-Capped Palladium(II) and Platinum(II) Complexes with Thiophene Spacers

“…The β-proton in the thiophene moiety adjacent to the metal site exhibits significant upfield resonances when compared to the free ligands, 1 . A similar behavior was also reported recently by Hor and co-workers for σ-thienyl complexes of palladium(II) …”

Catalytic and Stoichiometrically Directed Synthesis of Less Accessible Bromothiophenes and Bromobithiophenes. Trapping and Characterization of Catalytic Intermediates oftrans-PdBr(C4H4-nBrn-1S-C)(PPh3)2(n= 1−4),trans-PdBr(C8H4BrS2-C)(PPh3)2, andtrans,trans-Pd2Br2(μ-C

“…These catalytic reactions proceed through repetitive and sequential oxidative addition of the Pd(0) active catalyst with the C−Br bonds of the thiophene. The C−Br bond adjacent to the thiophenic sulfur is the most reactive and holds the key to the substitution at the α-position (Scheme ). This mechanism is supported by the trapping of the key intermediate trans -PdBr(3,4-C 4 HBr 2 S- C )(PPh 3 ) 2 ( 16 ), isolated from a stoichiometric reaction of 6 with Pd(PPh 3 ) 4 .…”