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

The titanium aryloxy bromides [Ti(OC6H3Ph2-2,6)2Br2]1 and [(2,6-Ph2C6H3O)2Ti(mu-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) 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 [Cp2Ti(mu-X)2TiCp2](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(mu-X)2Ti(OAr)2](ArO = 2,6-diphenylphenoxide), due to the presence of a titanium–titanium bonding interaction.