Action of Alkyl Halides on Homo- and Hetero- Porphyrin Dimers Involving a Rhodium-indium Bond, Producing Porphyrin Complexes Containing Metal-carbon and Metal-halide Bonds

The reactivity of the novel family of metalloporphyrin dimers containing a Rh-In bond towards alkyl halides is presented. The chemical reactivity of the homoleptic (same porphyrin ligand) and heteroleptic (different porphyrin ligand) porphyrin complexes with Rh-In metal-metal bond has been examined by photoand thermal-processes in the presence of alkyl halides under anaerobic conditions in the dark. The photolytic and thermal reactions have been studied to define the polarity of the Rh-In single bond, as well as to identify the products. The presence of complexes containing Rh-C bonds in the reaction mixture detected by UV-vis spectroscopy postulates the formulation Rh(I): + In(III)+ for the polarity of the metal-metal bond. In order to characterize the products we compare our spectroscopic results with those of the literature and those of authentic Rh-C containing complexes. As has been mentioned by Collman and coworkers,’ studies of multiple bonding between transition metals within discrete complexes offer fundamental insight into the nature of bonding between metal atoms. This understanding facilitates the prediction of physical properties and the reactivities of metal complexes containing metalmetal multiple bonds. We will focus on the chemistry of Rh-In single bond (one transition and one main group metal), and we will describe a total of four homoleptic and heteroleptic dimers. The properties of this metal-metal bond can be studied by changing variables one at a time. In this work, the variable under investigation is the electron density of the porphyrin ring. In 1982, Wayland and co-workers’ reported the reaction of (octaethylporphyrinato)rhodium(II) dimer [(OEP)Rh],, with Hz0 and CO to afford the formyl(octaethylporphyrinato)rhodium(III), *Author to whom correspondence should be addressed (0EP)RhCHO. An analogous system has been described by Miller and co-workers3 where the dimer [(OEP)Rh], reacted with CO in the presence of ethanol in CH2C12 to give (octaethylporphyrinato)rhodium(III) chloride, (ethoxycarbonyl) (octaethylporphyrinato)rhodium(III), and formyl(octaethylporphyrinato)rhodium(III). Photolysis of the latter in CH2C12 at 300 nm afforded (octaethylporphyrinato)rhodium(III) chloride. (Octaethylporphyrin)rhodium(II) dimer, also reacts with toluene and related methyl-substituted aromatics at the methyl C-H bonds to form organometallic benzyl derivatives.“ One more addition reaction of [(OEP)Rh], with propene, forming (OEP)Rh-CH,CH(CH,)-Rh(OEP) has been reported.5 The above very brief overview to the chemical reactivity of the Rh-Rh bond permits us to consider the importance of the reactivity study on complexes containing Rh-M bonds by various chemical reagents. Before closing the above overview it seems useful to refer to complexes of