Untersuchungen zur Reaktivität von Cyclopentadienylchromsulfiden Gegenüber Luftsauerstoff und Elektrophilen und Röntgenstrukturanalyse von Cp *2Cr 2(μ,η 2-S 2)(μ-S 2) (Cp * = η 5-C 5Me 5)

Abstract

The sulfur-rich complex Cp * 2Cr 2(μ,η 1-S,S)(μ,η 2-S 2)(μ-S) (I) reacts with PPh 3, under abstraction of the uncoordinated sulfur, to give Cp * 2Cr 2(μ,η 2-S 2)(μ-S) 2 (II) thus confirming the existence of a labile sulfur in I. An X-ray diffraction study of II has shown this process to proceed without rearrangement of the original framework. This means that both the S 2− and the S 2 2− ligand lie in a plane perpendicular to the MM Plane bisecting it. The S atoms form a trapezoid in contrast to the arrangement found in Cp * 2Cr 2S 5, which seems to be influenced by the μ,η 1-S,S ligand. Air oxidation of I gives the SO 3-adducts Cp * 2Cr 2S 4 · SO 3 (IV) and Cp * 2Cr 2S 5 · SO 3 (V). II gives these complexes IV and V only in trace amounts, but the oxidation of a weakly bound sulfur atom enhances this reaction. The SO 3 thus formed adds to nucleophilic sulfur bridges to give the products in good yields. This is independently confirmed by the formation of IV or V by reaction of I or II, respectively, with SO 3 · pyridine. The oxidation of I by Br 2 or I 2 is accompanied by the loss of one sulfur to yield compounds with the formulation Cp * 2Cr 2S 4X 2 (X  Br, I). Cp * 2Cr 2S 4I 2 can be reduced with Li 2S 2 under sulfide transfer to give I.