High temperature synthesis of some strontium and barium 2,6-dibenzylphenolates

Direct treatment of HOdbp (= 2,6-dibenzylphenol) with strontium or barium metal in the absence of solvent at high temperature provides the corresponding phenolates Sr(Odbp)2 and Ba(Odbp)2. Recrystallisation of Ba(Odbp)2 from THF gave a good yield of the crystalline dimer [Ba(Odbp)2(THF)]2 · 2THF. Attempted recrystallisation of Sr(Odbp)2 from THF mostly yielded microcrystalline material characterized as [Sr(Odbp)2]n but on one occasion gave a small crop of crystalline [Sr9(Odbp)8(O2SiMe2)4(OH)2(THF)6(OH2)2] · 6THF derived from the adventitious reaction of Sr(Odbp)2 with dimethylsilicone grease ({OSiMe2}∞). In the solid-state [Ba(Odbp)2(THF)]2 · 2THF displays significant intramolecular Ba⋯π-arene interactions with the pendant benzyl substituents. [Sr9(Odbp)8(O2SiMe2)4(OH)2(THF)6(OH2)2] · 6THF features a square prismatic [Sr(O2SiMe2)4]6− core capped by two inverse crown-like square [Sr4(Odbp)4(OH)(L)4]3+ units, where L = OH2 or THF, that are staggered with respect to the cuboidal core.

The syntheses of Sr(Odbp)2 and Ba(Odbp)2 from the high temperature treatment of 2,6-dibenzylphenol (HOdbp) with Sr or Ba metal and the X-ray crystal structures of [Sr9(Odbp)8(O2SiMe2)4(OH)2(THF)6(OH2)2] · 6THF and [Ba(Odbp)2(THF)]2 · 2THF, obtained by recrystallisation of M(Odbp)2 (M = Sr, Ba) from THF, are reported.Figure optionsDownload as PowerPoint slide