Crystal and Molecular Structures of the Copper(II) and Copper(III) Dithiooxalate Complexes (18-crown-6)₂K₂Cu(S₂C₂O₂)₂ and ([(C₆H₅)₃P]₂N)Cu(S₂C₂O₂)₂

The crystal and molecular structures of (18-crown-6)2K2Cu(Dto)2-DMF (I) and [(Ph3P)2N] [Cu(Dto)2] (II) are reported. I crystallizes in the monoclinic space group P21/c with two molecules per unit cell. The cell dimensions are a = 11.488 (2) Å, b = 8.543 (2) Å, c = 23.527 (7) Å, and β = 93.71 (2)°. II crystallizes in the monoclinic space group C2/c with four molecules in the unit cell. The cell dimensions are a = 13.528 (2) Å, b = 18.456 (2) Å, c = 15.354 (2) Å, and β = 95.82 (1)°. Intensity data for both I and II were collected with a four-circle computer-controlled diffractometer with the use of the θ-2θ step scan technique. The non-hydrogen atoms in I and II were refined with anisotropic temperature factors. Refinement by full-matrix least-squares techniques of 352 parameters on 2783 data for I and of 244 parameters on 2547 data for II gave final R values of 0.06 and 0.05 for I and II, respectively. The hydrogen atoms in I and II were included in the structure factor calculations but were not refined. In I the two independent CuII-S bond lengths in the planar [Cu(Dto)2]2- anion are 2.254 (2) and 2.268 (2) A, and the C-C bond length of the Dto ligand is 1.547 (7) A. The (18-crown-6)K+ cations are bound to the α-diketone portion of the coordinated Dto ligand and weakly interact with the oxygen atom of a DMF molecule of crystallization. The K-O distance within the crown ether is 2.91 (8) Å, and the K-O(Dto) distance is 2.78 (2) Å. In II the CuIII-S bond lengths within the [Cu(Dto)2]~ anion are 2.164 (1) and 2.178 (1) A. The C-C bond length of the Dto ligand in II, which readily undergoes photolytic cleavage, is 1.524 (7) A.