A reactivity change of a strontium monohydroxide by umpolung to an acid

Controlled hydrolysis of strontium amide LSN(SiMe3)(2)(thf) (L = CH(CMe2,6-i-Pr2C6H3N)(2)) (1) gave an unprecedented example of a hydrocarbon-soluble strontium hydroxide, [LSr(thf)(mu-OH)(2)Sr(thf)(2)L] (2). In compound 2, the tetrahydrofuran (THF) molecules can easily replaced by benzophenone and triphenylphosphine oxide to yield [LSr(mu-OH)(OCPh2)](2) (3) and [LSr(mu-OH)(OPPh3)](2) (4) compounds. Among the two strontium atoms of 2, one is coordinated to a single THF molecule, while the other is coordinated to two THF molecules. Interestingly, strontium hydroxide complex 2 behaves as an acid in its reaction with Zr(NMe2)(4) and results in a heterobimetallic oxide, [LSr(mu-O)Zr(NMe2)(3)](2) (5). Compound 5 is dimeric in the solid state and contains a Sr2Zr2O2 core.