The isolation and structure of titanium bromide compounds containing 2,6-diphenylphenoxide ligation; terminal and bridging ligand effects on Ti–Ti interactions

Abstract

The titanium aryloxy bromides [Ti(OC₆H₃Ph₂-2,6)₂Br₂] 1 and [(2,6-Ph₂C₆H₃O)₂Ti(μ-Br)₂Ti(OC₆H₃Ph₂-2,6)₂] 2 have been isolated and structurally characterized. Compound 1 adopts a pseudo-tetrahedral environment about titanium while 2 contains an edge-shared bis(tetrahedral) coordination geometry. The Ti–Ti distance is 3.0308(8) Å in 2. A comparison of these compounds with their chloride counterparts as well as cyclopentadiene analogues has been made. The Ti–Ti distance in the compounds [Cp′₂Ti(μ-X)₂TiCp′₂] (Cp′ = methylcyclopentadienyl) increases as the bridging ligand X is changed from Cl to Br. In contrast this parameter is almost identical in the aryloxide compounds [(ArO)₂Ti(μ-X)₂Ti(OAr)₂] (ArO = 2,6-diphenylphenoxide), due to the presence of a titanium–titanium bonding interaction.