Titanium Complexes Containing a Disulfide‐Bridged Bis(phenolato) Ligand: Synthesis and Structural Characterization of Three Different Bonding Modes

Abstract

A series of titanium(IV) complexes containing the 2,2′-dithiobis(6-tert-butyl-4-methylphenolato) ligand (dtbmp) were synthesized and characterized. Treatment of titanium tetra(isopropoxide) with 2,2′-dithiobis(6-tert-butyl-4-methylphenol) (dtbmpH2) gave, regardless of the molar ratio of the starting materials, a C2-symmetric dinuclear complex [Ti2(OiPr)2(μ2-OiPr)2(dtbmp)]. According to the results of a single crystal X-ray analysis, the two Ti(OiPr)2 fragments in this complex are bridged by a dtbmp ligand and two isopropoxide ligands. The disulfide link of the dtbmp ligand is bonded to each of the titanium centers [Ti−S 2.795(1) and 2.768(1) A], thus completing an octahedral coordination sphere around titanium. Reaction of [Ti2(OiPr)4(μ2-OiPr)2(dtbmp)] with Me3SiX (X = Br, I) gave the mononuclear complex Ti(dtbmp)X2. Crystallographic study revealed a distorted octahedral coordination with the disulfide link of the dtbmp dihapto-bonded through a relatively short Ti−S distance of 2.637(1) A (X = Br) or 2.645(2) A (X = I). Finally, the reaction of titanium tetra(n-butoxide) with dtbmpH2 gave a Ci-symmetric dimer [Ti2(OnBu)2(μ2-OnBu)2(dtbmp)2] that exhibits a monohapto coordination of the disulfide bridge in the dtbmp ligand with Ti−S bond lengths of 2.692(1) A and 2.694(1) A in the crystal.