Monocyclopentadienyl−Titanium Aryloxide Sulfide Complexes

In this report we extend titanium−sulfide chemistry, describing the syntheses, structures, and chemistry of monocyclopentadienyl−titanium aryloxide sulfide complexes. Reduction of Cp‘Ti(OC6H3-2,6-i-Pr2)Cl2 (Cp‘ = Cp (1), Cp* (3)) with n-BuLi affords the Ti(III) compounds [CpTi(OC6H3-2,6-i-Pr2)(μ-Cl)]2 (2) and [Cp*Ti(OC6H3-2,6-i-Pr2)(μ-Cl)]2 (4). Compound 2 is oxidized by moisture, giving [CpTi(OC6H3-2,6-i-Pr2)Cl]2(μ-O) (5). Oxidation of 4 by sulfur led to a mixture of uncharacterized products; however, reaction of 3 with 2 equiv of n-BuLi followed by subsequent addition of sulfur afforded a new diamagnetic species, Cp*Ti(OC6H3-2,6-i-Pr2)S5 (6). Oxidation of 2 by S8 yields [CpTi(OC6H3-2,6-i-Pr2)]2(μ-S)(μ-S2) (7). Reaction of the known sulfide-bridged dimer [CpTi(OC6H3-2,6-i-Pr2)(μ-S)]2 (8) with sulfur provides an alternative route to 7. The conversion of 7 to 8 is reversible as reaction of 7 with PPh3 yields SPPh3 and 8 quantitatively. Reaction of 1 with Li2S proceeds cleanly to give 8. Reduction of CpTi(OC6H3-2,6-i-Pr2)(SPh)Cl (9) with n-BuLi affords the diamagnetic product [CpTi(OC6H3-2,6-i-Pr2)(μ-SPh)]2 (10), which reacts with phenylpyridine to generate the paramagnetic species CpTi(OC6H3-2,6-i-Pr2)(SPh)(NC5H4Ph) (11). Attempts to isolate a monosulfide-bridged complex are described. Isolation of a monosulfide-bridged species, [CpTi(OC6H3-2,6-i-Pr2)2]2(μ-S) (14), is achieved via reaction of [CpTi(OC6H3-2,6-i-Pr2)2Cl (13) with Li2S. Structural data for 2, 4−7, 10, and 14 are reported. Comparisons are made with the related titanocene−sulfide systems, and the implications are considered.