Stability of cyclopentadienyl aryloxide complexes of calcium and barium

The synthesis of mono(cyclopentadienyl)aryloxide complexes of calcium and barium has been investigated. The reaction of ICa(ODipp)(thf)4 (Odipp = [2,6-iPr-OC6H3O]−) with K[C5Me5], (Cp3Si)2Ca (Cp3Si = C5(SiMe3)3H2) with K[ODipp], and IBa(BHT)(thf)3 (BHT = [2,6-tBu-4-Me-C6H2O]−) with K[C5Me5] in THF produces Cp*Ca(Odipp)(thf)3, (Cp3Si)Ca(Odipp)(thf)2, and Cp*Ba(BHT)(thf), respectively. The crystal structures of the two monomeric calcium complexes are reported. All three compounds are stable against Schlenk rearrangement in THF and aromatic solvents. DFT calculations suggest that the presence of THF has less of an effect on the thermodynamics of Schlenk rearrangements of the aryloxide systems than it does on comparable Cp′CaI compounds.