Thiophosphoryl Complexes of Bis(cyclopentadienyl)titanium. 1. Syntheses, Interconversions, and Structures

The reaction of (MeCp)₂Ti(CO)₂ (MeCp = η⁵-CH₃C₅H₄) with perthiophosphinic acid anhydrides, R₂P₂S₄, gives compounds of the formula (MeCp)₂TiS₄P₂R₂ (R = 4-C₆H₄OCH₃ (An), 2a; R = 4-C₆H₄OC₂H₅ (Pn), 2c) or (MeCp)₂TiS₃PR (R = t-Bu, 3b; R = 3-cyclohexenyl, 3c). The TiS₄P₂R₂ compounds could also be prepared from LiBHEt₃-reduced R₂P₂S₄ and (MeCp)₂TiCl₂ (or Cp₂TiCl₂). Spectroscopic studies indicate that the type 2 compounds contain TiSPPS rings. The reaction of Li₂S with R₂P₂S₄ gives Li₂S₃PR that was isolated in the case where R = An, 4. S₃PR^2- reacted with (MeCp)₂TiCl₂ to give the aforementioned (MeCp)₂TiS₃PR compounds in addition to 3a where R = An. ³¹P NMR studies suggest that 2a and 3a are in facile equilibrium (K_eq = 0.22), consistent with this 3a was found to react with [PhPS]₃ yielding a 1:2:1 mixture of the Ph₂, AnPh, and An₂ derivatives of the TiS₄P₂ compounds. Compound 3a reacts with NiCl₂(Ph₂PC₂H₄PPh₂) faster than does 2a giving (MeCp)₂TiCl₂ and Ni(S₃PAn)(Ph₂PC₂H₄PPh₂). A single-crystal X-ray diffraction study confirmed that 3a contains a TiSPS ring. 3a crystallizes in the space group P2₁/c with a = 7.304 (2) Å, b = 13.716 (3) Å, c = 23.995 (6) Å, and β = 111.28 (2)°. The structural parameters of 3a are compared with (Me₅C₅)₂TiS₃ and Me₂P₂S₄.