Electrochemical Studies of Rhodium-Carbon Bond Formation. The Reaction of Monomeric (Tetraphenylporphinato)rhodium(II) with Alkyl and Aryl Halides

Article abstract of DOI:10.1021/ja00238a019

The reaction of electrochemically generated (TPP)Rh (where TPP is the dianion of tetraporphyrin) with 24 different alkyl or aryl halides (RX) was monitored by electrochemical and spectroelectrochemical methods. (TPP)Rh was generated by the one-electron reduction of <(TPP)Rh(L)2>⁺Cl^-, where L is dimethylamine.The reduced rhodium complex reacts with alkyl halides in solution to form (TPP)Rh(R) and X^-, and the synthesis of 14 different (TPP)Rh(R) complexes by this method is reported.However, no reaction between (TPP)Rh and aryl halides is observed.Relative reaction rate constants for the reaction between (TPP)Rh and the alkyl halides were evaluated as a function of both the halide, X, and the R group of the alkyl halide.In general, the dependence of the reaction rate constants on the halide followed the trend I > Br > F >/= Cl, while the dependence of the reaction rate constants on R of the straight chain isomers followed the trend CH3 > C2H5 ca.C3H7 ca.C4H9 ca.C5H11.On the basis of these results, a general discussion of the reaction mechanism for the formation of (TPP)Rh(R) from (TPP)Rh and RX is presented.