Synthesis and characterization of phenylimidorhenium(V) compounds containing polypyridyl ligands. Crystal structures of mer-[Re(NPh)Cl3(bipy)], trans-[Re(NPh)(OEt)(bipy)2][PF6]2 and trans-[Re(NPh)Cl2(terpy)]PF6(bipy = 2,2′-bipyridine, terpy = 2,2′:6′,2″-terpyridine)

Abstract

The reaction between mer-[Re(O)Cl₃(L–L)][L–L = 2,2′-bipyridine (bipy) or 4,4′-dimethyl-2,2′-bipyridine] and aniline in refluxing o-xylene gave phenylimido compounds formulated as mer-[Re(NPh)Cl₃(L–L). These compounds do not react with an alcohol (ROH) to form alkoxyimido compounds of the type cis-[Re(NPh)(OR)Cl₂(L–L), but in the presence of an excess of the polypyridyl ligand, salts of the cation trans-[Re(NPh)(OEt)(L–L)₂]²⁺ were obtained. When salts of trans-[Re(NPh)(OEt)(L–L)₂]²⁺ were dissolved in MeCN solutions containing a few drops of concentrated hydrochloric acid rapid reaction occurred that resulted in the isolation of mer-[Re(NPh)Cl₃(L–L)]. The salt trans-[Re(NPh)Cl₂(terpy)]PF₆ was prepared from the reaction between mer-trans-[Re(NPh)Cl₃(PPh₃)₂], and 2,2′:6′2″-terpyridine (terpy) in refluxing ethanol. The spectroscopic and electrochemical properties of these compounds were investigated and the structures of mer-[Re(NPh)Cl₃(bipy)], trans-[Re(NPh)(OEt)(bipy)₂][PF₆]₂ and trans-[Re(NPh)Cl₂(terpy)]PF₆ determined by X-ray crystallography.