Anion complexes gold dithiocarbamates

These short Au-Au contacts may be compared with distances of 2.88 A in metallic gold and 2.60 A in gaseous Au2. The term aurophilicity has been coined by H. Schmidbaur to describe the phenomenon [189,194], The interactions can occur as pairs, squares, linear chains or two-dimensional arrays of gold centres. Examples include the association between dimer units in the dithiocarbamates Au(dtc)2 (Figure 4.16) and the ionic tetrahydrothiophen complexes Au(tht)2 AuXJ (X = halogen), where cations and anions stack with Au—Au 2.97-2.98 A (X = I). The interaction is such that Au(S203)2 pair up, despite their charge, with Au-Au 3.24 A in the sodium salt. Likewise in Aupy AuCl, cations pair up at 3.42 A apart [10, 195]. 

A dinuclear selenide complex anion [Au2(M-Se)2(Se4)2] is the product of the reaction" between [AuCN] and Na2 Ses. Square-planar gold(IIl) complexes are readily formed by a variety of bidentate sulfur-donor ligands such as toluene-1,2-dithiolate, maleonitriledithiolate, and dithiocarbamate. On oxidation with CI2 or Br2, [ Au(S2CNR)2 2] forms Au -Au complexes, which may be oxidized further to an Au complex. 

Crystallographic studies of ionic bis(dithiocarbamate) complexes aU reveal a distorted square-planar gold(lll) center (421, 422,1 825). In [Au(S2CNEt2)2] [TcNCLt], an interesting secondary interaction is seen, two anions and one cation assembling via coordination of a sulfur to the vacant coordination site at the technetium center [Tc-- S 3.451(5)-3.568(5) A] (Fig. 250), the second cation remains uncoordinated (421). 

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