Highly Oxidizing Organometallics: Physicochemical Characterization of (MethylcyclopentadienyOvanadium(Ilf) Trichloride and Related Vanadium(III) and Titanium(III) Derivatives

The compound (MeCp)VCl₃ (1) (Cp = η-C₅H₅) may be synthesized in high yield and purity from (MeCp)₂VCl₂ and SOCl₂. Compound 1 crystallizes in the space group P1 with cell dimensions a = 6.860 (2) Å, b = 11.037 (4) Å, c = 6.832 (2) Å, α = 97.37 (3)°, β = 118.77 (2)°, γ = 80.73 (3)°, and Z = 2; R_w = 0.087, R = 0.069 for 1860 Mo Kα data with I > 2.85σ(I). Vanadium-chlorine bond lengths range from 2.187 (4) to 2.208 (4) Å and the mean V-Cp distance is 1.93 (1) Å. Compound 1 undergoes a reversible reduction at +425 mV (Ag/AgCl), which may be compared with (MeCp)VOCl₂ (+270 mV) and (MeCp)TiCl₃ (-355 mV). Compound 1 shows a well-resolved paramagnetically shifted ¹H NMR spectrum. In comparison with the ¹H NMR signals of isoelectronic [Cp₂Co][(MeCp)TiCl₃], those observed for 1 indicate more covalent M-Cp interactions in 1 than in [Cp₂Co][(MeCp)TiCl₃]. Magnetic susceptibility measurements on solid [Cp₂Co][(MeCp)VCl₃] indicate a zero field splitting value of 8 cm^-1.