is a Lewis acid as implicated by its tendency to hydrolyze. With the ether THF,  reacts to give yellow crystals of . With chloride salts,  reacts to form sequentially ,  (see figure above), and . The reaction of chloride ions with  depends on the counterion.  and  gives the pentacoordinate complex , whereas smaller  gives . These reactions highlight the influence of electrostatics on the structures of compounds with highly ionic bonding.