Synthesis, structure, and characterization of N-ligated tungsten selenide cluster complexes W6Se8L6

Treatment of W6Cl12 with Na2Se in refulxing pyridine (py) and piperdine (pip) generate W6Se8(py)6 (2) and W(sub 6-)Se8(pip)6 (1). Both the complexes containan octahedron of tungsten atom having eight triply-bridged selenium atoms capping the octahedra faces. The average W-W and W-Se bond distance values for 1 and 2 are 2.691(1) and 2.574(1) angstroms respectively. Photoelectron spectra indicate typical tungsten binding energies at 30.8 eV (W 4f(sub7/2)) and 32.9 eV (W 4f(sub 5/2)). Characteristic IR spectra are obtained at 243-254 per centimeter due to T(sub 1u) W-Se stretching modes.