87198-32-1

Upstream product

• 36670-30-1 RhCl(octaethylporphyrin) 
• 36670-30-1 (2,3,7,8,12,13,17,18-octaethylporphyrinato)rhodium(III) chloride 
• 108-88-3 toluene 

Relevant academic research and scientific papers

Aromatic and benzylic C-H bond activation in the system bis(dicarbonylrhodium(I))porphyrinate-hydrocarbon solvent

Metalation of C6H6 has been known for a long time as a aside reaction occuring in refluxing benzene solutions of Rh2(CO)4(TPP) (TTP = tetraphenylporphyrin). Rather than representing the intrinsic reactivity of this complex, such hydrocarbon activation proceed via RhII(por) and RhIII(por) derivatives resulting from oxidation can be extended to other aromatic substrates and represents an effecient synthetic route to certain organometallic RhIII(TPP) derivatives.

Activation of arene carbon-hydrogen bonds. Highly regioselective, electrophilic aromatic metalation with rhodium(III) porphyrin and subsequent cleavage of carbon-rhodium bond

(Octaethylporphyrinato)rhodium(III) chloride, (OEP)RhIIICl, reacts with benzene in the presence of AgClO4 or AgBF4 to give the phenyl-rhodium(III) complex. Anisole, toluene, and chlorobenzene are similarly metalated exclusively at the para positions. The metalation of methyl benzoate, on the other hand, gives a 92:8 mixture of meta- and para-metalated isomers. The reactivities of arenes follow the Hammett equation with the ρ value of -5.43. The observed substituent effects both on reactivity and orientation unambiguously characterize the present reaction as an electrophilic aromatic metalation with a [(OEP)RhIII]+ intermediate generated from the anion exchange of (OEP)RhIIICl with silver salts. The slow step in the reaction is coordination of arene to form [(OEP)Rh(arene)]+, which subsequently loses a proton. Arenes thus activated with rhodium undergo photochemical homolysis of the C-Rh bond as well as its halogen-induced heterolysis. The photolysis in benzene leads to 4-substituted biphenyls and the halogenolysis gives p-haloarenes with extremely high regioselectivities (>99%).

Activation of Arene Carbon-Hydrogen Bonds. Direct Electrophilic Aromatic Metallation with a Rhodium-Porphyrin Complex

Anion exchange of octaethylporphyrinatorhodium(III) chloride with AgClO4 or AgBF4 results in the formation of a highly electrophilic RhIII-porphyrin capable of direct metallation of arenes.