Crown ether complexes of titanium(IV) chloride and bromide and the structures of the hydrolysis products [Ti2Cl6(m-O)(18-crown-6)2] and [Ti4Cl8(m-O)4(15-crown-5)4]

The titanium(IV) complexes of 12-crown-4, 15-crown-5 and 18-crown-6 and of 1,4-dithia-7,10,13trioxacyclopentadecane (L) of type [TiX4(2-L)](X = Cl or Br, L = 15-crown-5 or 18-crown-6; X = Br, L = 12-crown4) and [TiCl4(L)] have been prepared from TiX4 and the ligands in anhydrous toluene, and characterised by analysis, IR, UV-visible and 1H NMR spectroscopy. Complexes with TiI4 do not form under similar conditions. The [TiCl4(L)] complex contains the thia-oxa-crown coordinated via sulfur to the titanium. The complexes are extremely readily hydrolysed and examples of the first two stages of the hydrolysis have been characterised by X-ray crystallography. These are the dimer [(18-crown-6)Cl3Ti(µ-O)TiCl3(18-crown-6)] which contains a single non-linear oxo-bridge linking two six-coordinate titanium centres also coordinated 2 to 18-crown-6 and to three (mer) chlorines. The second product is the tetrameric [{TiOCl2(15-crown-5)}4] in which there is an eightmembered ring composed of alternating Ti and O, each titanium also coordinated 2 to 15-crown-5 and two terminal (cis) chlorines.