Halogen exchange by reaction of CpRu(Cl)(PPh3)2 with MeC(O)X (X = Br, I) and its mechanistic study

Mechanism of halide exchange in reactions of CpRu(PPh3)2Cl with haloalkanes

“…1). 4 In our hands, metathesis reactions (pathway i) with alkali metal salts gave variable yields of 2-3. Protonation of cyclopentadienylruthenium bis(triphenylphosphine) hydride, CpRu(PPh 3 ) 2 H, with strong acids produce high yields of 2a and 3a but requires the isolation of air and moisture sensitive ruthenium hydrides (pathway ii).…”

Kinetics of phosphine substitution in CpRu(PPh3)2X (X = Cl, Br, I, N3, and NCO)

“…The observation of halide exchange reactions between CpRu(PPh 3 ) 2 X and CDCl 3 has not been previously reported 28 for 1b-e although reaction between 1a and acetyl halides, CH 3 COX where X ¼ Br and I, was recently reported to yield 1b-c. 29 An increase in the rate of halide exchange was observed in the presence of 9,10-dihydroanthracene (radical initiator) and a concomitant decrease in conversion when TEMPO (radical trap) is added to the reaction mixture supporting a radical mechanism. Computational chemistry suggested a pathway where phosphine dissociation is followed by halogen atom abstraction from CH 3 COX and formation of a radical pair.…”

“…Computational chemistry suggested a pathway where phosphine dissociation is followed by halogen atom abstraction from CH 3 COX and formation of a radical pair. 29 Further support for radical intermediates in the chemistry of 1 is found in the catalytic activity of CpRu(PPh 3 )(PMe 3 )Cl in the atom transfer radical addition (ATRA) reactions of CCl 4 and styrene. 30 There are also two reports of the reaction between 1a and excess iodomethane yielding 1c in situ and as a synthetic method but the mechanism of the reaction was not explored.…”

Microbial Electroreduction: Screening for New Cathodic Biocatalysts

“…A halogen exchange reaction is a synthetically interesting reaction proceeding in the presence of various transition metal compounds, including ruthenium complexes 13. The Ru‐catalyzed halogen exchange has been observed with triflates ([Cp*Ru(MeCN) 3 ]OTf and LiBr)14 and acyl halides (CpRuCl(PPh 3 ) 2 with Me(CO)X, X=Cl, Br, I) 15. As for the reaction mechanism of the Ru‐catalyzed halide exchange, two hypotheses have been proposed.…”