4-Phenyl-1,2,4-triazoline-3,5-dione (PTD) reacts with (CH3C5H4)2V2(μ-S) 2(μ-η1-S2) (1) to yield primarily (CH3C5H4)2V 2(μ-S)(μ-η2-S2)(μ-η 1-PTD) (2) along with other minor products. The structure of 2 was inferred from the structure of its Pt(PPh3)2 adduct (CH3C5H4)2V2S 3(PTD)Pt(PPh3)2 (5), which was determined by single-crystal X-ray diffraction techniques. The crystals of 5 belong to space group P21/c with a = 22.181 (7) Å, b = 13.176 (4) Å, c = 19.303 (5) Å, β = 111.10 (2)°, Z = 4. Conventional full-matrix least-squares refinement with non-carbon atoms anisotropic, carbon atoms independently isotropic, and hydrogen atoms identically isotropic gave R = 0.059 and Rw = 0.065 for 6934 reflections having 2θ < 55° and I > 3σ(I). The structure consists of an isosceles triangle of metal atoms capped by two μ3-S ligands, with the V-V edge spanned by a μ-S and a μ-η1-PTD ligand. An evaluation of the V-S and V-Pt distances indicates that formation of the Pt(PPh3)2 adduct effects only minor perturbations on the electronic structure of 2. Compound 2 is efficiently desulfurized by tri-n-butylphosphine to yield (CH3C5H4)2V2(μ-S) 2(μ-η1-PTD) (3). Compound 3 reacts further with PTD to yield (CH3C5H4)2-V2S 2(PTD)2 (4). Both 3 and 4 are minor products of the reaction of 1 with PTD. The high symmetry of 3 and 4 is supported by spectroscopic measurements. Compound 4 forms a stable Pt(PPh3)2 adduct, (CH3C5H4)2V2S 2(PTD)2Pt(PPh3)2 (6), whose properties indicate a structure consisting of a [(CH3C5H4)V]2 moiety bridged by two μ-η1-PTD ligands and a μ-η2-S2Pt(PPh3)2 ligand. The structure of 4 thus arises from oxidative coupling of the two μ-S ligands in 3. Comparison of 2 and 3 with (CH3C5H4)2V 2(μ-S)(μ-η1-S2)(μ-η 2-S2) and (CH3C5H4)2V2(μ-S) 2(μ-η1-S2) illustrates that the μ-η1-PTD ligand functions as prosthesis for the μ-η1-S2 ligand in these cyclopentadienylvanadium dimers.
ASJC Scopus subject areas
- Colloid and Surface Chemistry