The Five-Coordinate Cadmium Halide Bis(diethyldithiocarbamate) Complexes [PPh4][Cd(S2CNEt2)2Cl] and [PPh4][Cd(S2CNEt2)2Br]

The title compounds, tetraphenylphosphonium chloro bis(diethyldithiocarbamato-S,S)cadmium(II), (C24H20P)[CdCl(C5H10NS2)2], (1), and tetraphenylphosphonium bromobis(diethyldithiocarbamato-S,S)cadmium(II), (C24H20P)[CdBr(C5H10NS2)2], (2), are isomorphous. The compexes are mononuclear with coordination spheres of the types S4Cl and S4Br, respectively. The central Cd atom is linked to four S atoms and two bidentate dithiocarbamate ligands and to the halide atom. The resulting Cd atom coordination geometry is halfway between trigonal bipyrimidal and square pyramidal. Principal dimensions include Cd—S 2.573 (1)–2.682 (1) in (1) and 2.571 (3)–2.736 (2) A in (2). The Cd—Cl and Cd—Br distances are 2.462 (1) and 2.626 (1) A, respectively.

The authors would like to thank Fundaci6n Andes for the purchase of the single-crystal diffractometer currently operating at the Universidad de Chile.
Lists of structure factors, anisotropic displacement parameters, leastsquares-planes data, H-atom coordinates and complete geometry have been deposited with the IUCr (Reference: JZI082). Copies may be obtained through The Managing Editor, International Union of Crystallography, 5 Abbey Square, Chester CHI 2HU, England.  Srlido, Departamento de F[sica, Comisi6n Nacional de Energ[a Atrmica, Av. del Libertador 8250, 1429Buenos Aires, Argentina, bDepartamento de F&ica, Facultad de Ciencias F&icas y Matern~ticas, Universidad de Chile, Casilla 487-3, Santiago de Chile, Chile, and 'Departamento de Qufmica Inorgrnica, Anafftica y Qufmica Ffsica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellrn II, 1428Buenos Aires, Argentina. E-mail: baggio @ cnea. edu.ar (Received 6 June 1995accepted 9 October 1995) Abstract The title compounds, tetraphenylphosphonium chlorobis ( case of [NEt4][Cd(S2CNEt2)2NCS], single crystals were obtained and the structure was determined by X-ray crystallography. The adduct was found to be mononuclear with a distorted CdSaN nuclear core. Based on vibrational data the cadmium complexes with X = CI, Br and I also appeared to have five-coordinate mononuclear units, although on this basis alone the presence of sulfuror halide-bridged coordination to give the more usual hexacoordinate Cd" complexes could not be excluded. Herein we report the isolation of single crystals of The crystal data for (1) and (2) show that the complexes are isomorphous. Fig. 1 presents the structural diagram and the atomic numbering scheme for (1). Both anions have five-coordinate mononuclear CdS4X units in which the metal atom is coordinated to four S atoms of two bidentate dithiocarbamate ligands and to the X atom of the halide ligand. Atoms S 1, $4 and X (X = C11 or Brl) define the equatorial planes, and the Cdl atoms are 0.0902 (4) in (1) and 0.0886 (6),~ in (2) below the corresponding planes pointing towards $3. The Cdl--$2 and Cdl--S3 axial bonds show average deviations of 20 (1) and 25 (1) ° from the normal to the equatorial planes, which may be attributed to the acute bite angles of the spanning dithiocarbamate ligands [mean 67.85 (7) in (1) and 67.87 (6) ° in (2)].
The complexes exhibit a wide range of Cd----S bond lengths, with the equatorial Cd--S bonds significantly shorter than the axial bonds and with one bidentate ligand more asymmetrically bonded than the other [2.573 (1)-2.731 (1) and 2.615 (1) . It thus appears that the nature of the halide does not significantly alter the Cd--S bond lengths in these five-coordinate complexes.
The calculated values of 0.50 for complexes (1) and (2) describe a type of structure which is 50% along the pathway of distortion from ideal square-pyramidal (7-= 0) towards ideal trigonal-bipyramidal geometry (r = 1). The related compound [NEt4][Cd(S2CNEt2)2NCS] shows a further distortion towards square-pyramidal geometry (7-= 0.27). The coordination flexibility of five-coordinate Cd" is well known (Btirgi, 1973) and undoubtedly reflects the d 1° electron configuration of the metal ion, which rules out any ligand stabilizing effects in cadmium complexes.
Intermolecular distances in the reported complexes are larger than the corresponding sum of the van der Waals radii. Angles and other metric parameters of the ligands, as well as of the PPhg cations, can be regarded as unexceptional.

Experimental
All commercially available reagents and chemicals were of analytical or reagent-grade purity and used as received.