Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]2(μ-OEt)2} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)2·M(solv)2] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands.