The reactions of K 2ReX 6 (X = Br OR I) and Re 3X 9 (X = Cl, Br OR I) with alkyl and aryl isocyanides

Abstract

The reactions of alkyl isocyanides (RNC) and aryl isocyanides (ArNC) with the rhenium halides K 2ReX 6 (X = Br or I) and Re 3X 9 (X = Cl, Br or I) have been investigated. When the K 2Rex 6 salts are treated with neat isocyanide at room temperature, or with isocyanide ligands in polar solvents under reflux conditions, then the homoleptic isocyanide cations [Re(CNR) 6] + or [Re(CNAr) 6] +, are isolated. Under less forcing conditions, various rhenium(III) and rhenium(I) species, e.g. [Re(CNCMe 3) 5I 2] + and Re(CNAr) 5I, which may be considered as intermediates on the way to the formation of the homoleptic species, can be obtained. The rhenium(I) complexes Re(CNAr) 5I 3, which are believed to contain the coordinated triiodide ligand, have also been isolated and characterized. One route to these complexes is through the reaction of Re(CNAr) 5I with I 2. Reactions of the trinuclear halides Re 3X 9 (X = Cl, Br or I) with alkyl isocyanides at room temperature are found, in all instances, to provide adducts of the type Re 3X 9(CNR) 3. Under reflux conditions, Re 3Cl 9 and Re 3Cl 9(PEtPh 2) 3 react with Me 3CNC to fom products of cluster disruption, viz. [Re(CNCMe 3) 6] + and [Re(CNCMe 3) 4(PEtPh 2) 2] +, respectively. The spectroscopic and electrochemical properties of complexes derived in this study are reported. These results are compared with those reported previously by Freni et al.