Optical, electrochemical and structural studies on the first rhenium compound of di-2-pyridylketonephenylhydrazone (dpkphh), fac-Re(CO)3(dpkphh)Cl

fac-Re(CO)(3)(dpkphh)Cl isolated from the reaction between Re(CO)(3)Cl and dpkphh in refluxing toluene exhibits rich physico-chemical properties. Spectroscopic measurements on fac-Re(CO)(3)(dpkphh)Cl revealed strong solvent dependence as manifested by the high sensitivity of its H-1 NMR and electronic absorption spectra to solvent variation. Electrochemical measurements on fac-Re(CO)(3)(dpkphh)Cl in CH2Cl2 show irreversible/quasi-reversible redox processes pointing to electrochemical transformation(s) following electronic-transfer(s). Crystals of fac-Re(CO)(3)(dpkphh)Cl.CH3CN obtained from an acetonitrile solution of fac-Re(CO)(3)(dpkphh)Cl are chiral and structural studies show racemic twins of fac-Re(CO)(3)(dpkphh)Cl.CH3CN with fac-Re(CO)(3)(dpkphh)Cl molecules in distorted octahedral geometry. The molecules pack shows stacks of well separated strands of fac-Re(CO)(3)(dpkphh)Cl-CH3CN in double helix formation with a network of hydrogen bonds that include solvent-solute and solute-solute interactions. The interlocked helical structure of fac-Re(CO)(3)(dpkphh)Cl.CH3CN and weak bond energies of the non-covalent interactions may account for the optical behavior of fac-Re(CO)(3)(dpkphh)Cl.CH3CN as any slight interaction between this system (fac-Re(CO)(3)(dpkphh)Cl and surrounding solvent molecules) and its surroundings may disrupt the weak solvent-solute and solute-solute interactions. (C) 2002 Elsevier Science B.V. All rights reserved.