Titanocene-mediated formation of phosphorus-phosphorus bonds

The reaction of Cp2Ti(btmsa) [btmsa = bis(trimethylsilyl)acetylene (Me3SiC CSiMe3)] with bulky dichlorophosphines leads to the formation of diphosphenes or dichlorodiphosphines depending on the stoichiometry used. (Me3Si)(2)NN(SiMe3)PCl2 (1) was transformed either into bis[tris(trimethylsilyl)hydrazino]dichlorodiphosphine (2) or bis[tris(trimethylsilyl)hydrazino]diphosphene (3) depending on whether an excess of 1 or Cp2Ti(btmsa) was used. Depending on the starting material ratios, Cp2TiCl2 or (Cp2TiCl)(2) were obtained as byproducts besides 1 or 3. Compounds 2 and 3 were structurally characterized by X-ray diffraction. Furthermore, the known diphosphene Mes*P=PMes* (4) (Mes* = 2,4,6-tri-tert-butylphenyl) and the dichlorodiphosphine Mes*(Cl)PP(Cl)Mes* (5) were prepared by reaction of Cp2Ti(btmsa) with Mes*PCl2. The reaction of Cp2Ti(btmsa) with the sterically less demanding PhPCl2 resulted in the isolation of a triphosphinato complex. The diphosphine Ph2P-PPh2 (6) was synthesized by reaction of Ph2PCl with Cp2Ti(btmsa).