| Abstract: | Chalcogen Derivatives of the Halfsandwich Tungsten(V) Complexes Cp*WCl4 and Cp*WCl4(PMe3). X‐Ray Crystal Structure Analyses of anti ‐Cp*W(Se)(μ‐Se)]2 and Cp*W(S)2(OMe) The chalcogenation of Cp*WCl4 ( 1 ) by E(SiMe3)2 (E = S, Se) and Te(SiMe2tBu)2 in chloroform solution leads to dimeric products of the type anti‐Cp*W(E)(μ‐E)]2 (E = S ( 3 a ), Se ( 3 b ) and Te ( 3 c )). An X‐ray structure determination of 3 b indicates a centrosymmetric molecule containing a planar W(μ‐Se)2W ring, the W–W distance (297.9(1) pm) corresponds to a single bond. In the presence of air the two terminal chalcogenido ligands (E) in 3 a – c are stepwise replaced by oxido ligands (O) to give Cp*W(O)(μ‐E)]2 (E = S ( 5 a ), Se ( 5 b ) and Te ( 5 c )) in quantitative yields. The reaction of Cp*WCl4 with H2S or ammonium polysulfide, (NH4)2Sx (x ～ 10), leads to Cp*W(S)2Cl ( 6 a ); the corresponding methoxy derivative, Cp*W(S)2OCH3 ( 9 a ), has been characterized by an X‐ray structure analysis. On the other hand, the reaction of Cp*WCl4(PMe3) ( 2 ) with sodium tetrasulfide, Na2S4, in dimethylformamide solution gives a mixture of mononuclear Cp*W(S)(S2)Cl ( 8 a ), dinuclear Cp*W(S)(μ‐S)]2 ( 3 a ) and a trinuclear side‐product of composition Cp*2W3S7 ( 13 a ). Terminal sulfido ligands are replaced by terminal oxido ligands in solution in the presence of oxygen. Thus, 6 a is stepwise converted into Cp*W(O)(S)Cl ( 10 a ) and CpW(O)2Cl ( 12 a ), whereas 8 a gives Cp*W(O)(S2)Cl ( 11 a ) and 13 a leads to Cp*2W3(O)S6 ( 14 a ). The disulfido complexes 8 a and 11 a are desulfurized by triphenylphosphane to give 6 a and 10 a . The new complexes have been characterized by their IR and NMR spectra and by mass spectrometry. |
