Synthesis, Characterization and Structural Studies on the First Rhenium Complex with Di(2-pyridyl) Ketone 2,4-Dinitrophenylhydrazone (dpkdnph),fac-[Re(CO)3(dpkdnph)Cl

Abstract

When di(2-pyridyl) ketone 2,4-dinitrophenylhydrazone (dpkdnph) was allowed to react with [Re(CO)5Cl] in refluxing toluene fac-[Re(CO)3(dpkdnph)Cl] was formed in good yield. Spectroscopic measurements on fac-[Re(CO)3(dpkdnph)Cl] revealed strong solvent dependence as manifested by the high sensitivity of its electronic absorption spectra to solvent variation. Electrochemical measurements on fac-[Re(CO)3(dpkdnph)Cl] in DMF show electrochemical properties with quasi-reversible reductions following an irreversible one-electron transfer. Structural studies on a brown crystal of fac-[Re(CO)3(dpkdnph)Cl]·CH3CN grown from an acetonitrile solution of fac-[Re(CO)3(dpkdnph)Cl] show well separated linear CH3CN and pseudo-octahedral fac[Re(CO)3(dpkdnph)Cl], with the major distortion about rhenium being due to the bidentate binding of dpkdnph to form a six-membered Re−N−C−C−C−N metallacyclic ring in a boat conformation. The molecular packing shows a web of fac-[Re(CO)3(dpkdnph)Cl]·CH3CN units interlocked via a network of intra- and intermolecular non-covalent interactions that include donor/acceptor and hydrogen bonds.