New rhenium(V) nitrofuryl semicarbazone complexes. Crystal structure of [ReOCl2(PPh3)(3-(5-Nitrofuryl)acroleine semicarbazone)]

Abstract

The synthesis and characterization of the first two Re complexes with semicarbazone ligands is presented. Selected ligands are 5-Nitro-2-furaldehyde semicarbazone (Nitrofurazone) (L1) and its derivative 3-(5-Nitrofuryl)acroleine semicarbazone (L2). Complexes of general formula [RevOCl2(PPh3)L], where L = L1 and L2, were prepared in good yields and high purity by reaction of [RevOCl3(PPh3)2] with L in ethanol or methanol solutions. The complexes formula and molecular structures were supported by elemental analyses and electronic, FTIR, 1H, 13C and 31P NMR spectroscopies. In addition, the crystal and molecular structure of [RevOCl2(PPh3)L2] was determined by X-ray diffraction methods. [ReOCl2(PPh3)(3-(5-Nitrofuryl)acroleine semicarbazone)] crystallizes in the space group P-1 with a = 11.2334(2), b = 11.3040(2), c = 12.5040(2) Å, α = 81.861(1), β = 63.555(1), γ = 83.626(1)°, and Z = 2. The Re(V) ion is in a distorted octahedral environment, equatorially coordinated to a deprotonated semicarbazone molecule acting as a bidentate ligand through its carbonylic oxygen and azomethynic nitrogen atoms, to an oxo ligand and a chlorine atom. The six-fold coordination is completed by another chlorine atom and a triphenylphosphine ligand at the axial positions.