The reaction of Li2S2 with (CH3C5H4)TiCl3 followed by exposure to oxygen gives both (CH3C5H4)4Ti4S 8O (1) and (CH3C5H4)4Ti4S 8O2 (2). Also isolated was the mixed-ligand complex (C5H5)(CH3C5H4) 3Ti4S8O2 (2″), which arises from an impurity in the starting material. Compound 1 can be converted to 2 by using (NBu4)IO4, m-chloroperoxybenzoic acid, and tert-butyl hydroperoxide. Experiments with 1 and its (C5H5) analogue indicate that this transformation occurs without cluster fragmentation. The compounds were purified chromatographically and were characterized by spectroscopic and, for 2, crystallographic methods. 1H NMR studies over the temperature range -70 to +90°C show that 1 is dynamic, as the methyl groups give rise to four resonances at low temperatures that merge into three resonances at higher temperatures. The 1H NMR spectrum of 2, which does not vary over the temperature range of +80 to -70°C, shows two methyl resonances and eight cyclopentadienyl ring proton resonances, two of which are coincident. Relative to 2, the 1H NMR spectrum of 2″ shows the following differences: (i) one of the two methyl resonances is halved in intensity and is shifted upfield, (ii) three of the eight ring proton resonances are halved in intensity, and (iii) one of the eight ring proton resonances overlaps with the single C5H5 peak. Complex 2 crystallizes in the trigonal space group P3121 with a = 10.700 (2) Å, c = 22.530 (6) Å, V = 2233.9 (9) Å3, and ρobsd = 1.75 g/cm3 (ρcalcd = 1.77 g/cm3 for Z = 3). The structure was solved by direct methods leading to a final R = 0.0234 (Rw = 0.0246) with all non-hydrogen atoms anisotropic. The molecule possesses crystallographic C2 symmetry and consists of a Ti4(μ4-O) core with two Ti atoms further bridged by an oxo ligand. Each of the four faces of the tetrahedral Ti4O core is capped by a μ3-S2 ligand.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry