PNNL

Abstract

The ability of the actinide elements to covalently bond to ligands is not well understood. A computational effort for compounds of the formula [Cp2AnS2C2H2]-1,0,+1 where An = U, Np, or Pu has shown that the angle between the plane formed by the two sulfurs and the plane formed by the two sulfur atoms and the two carbons converges to 70 – 75° when the ligand is in the dithiolate state (-2 charge on the ligand). Upon oxidation of [Cp2NpS2C2H2]0 or [Cp2PuS2C2H2]0 the electron is removed from the dithiolate rather than the actinide and the dihedral angle is reduced to planarity. The reaction of NpCl4DME2 with deprotonated benzene dithiol shows an intense color change suggestive of a charge transfer complex. The binding of the benzene dithiol as the dithiolate to the neptunium metal center is supported by visible, infrared and NMR spectroscopies.