Mixed Metal Multinuclear Cr(III) Cage Compounds and Coordination Polymers Based on Unsubstituted Phenolate: Design, Synthesis, Mechanism, and Properties

Oxidative
substitution reactions of chromium­(II) chloride with
lithium phenoxide in the presence of water give access to new polynuclear
chromium­(III) aryloxide complexes and coordination polymers. While
a one-dimensional coordination polymer based on chromium­(III), [Cr2(μ3-OPh)2­(μ-OPh)6­(μ-OH)­(μ3-Li)4­(μ3-Cl)2­Li­(THF)6]n, is first obtained by serendipity,
the controlled addition of water to the initial Cr­(II) complex as
well as variation of the stoichiometry lead to three new discrete
chromium­(III) aggregates, namely, [Cr­(OPh)4­(μ-OH)­Li2(THF)3]2, [Cr3Li3­(OPh)9­(μ3-OH)­(μ3-O)­(THF)6], and [Cr4(μ-OPh)8­(μ3-OH)6­(μ-OH)2­Cl2Li6­(THF)­6]·2THF.
The use of deuterated species allowed confirmation of the oxidation
based on the addition of water by detection of H2, HD,
and D2. During these investigations, we have also identified
a THF-adduct of chromium­(II) chloride, [CrCl2(THF)2], used in the literature as a precursor in numerous syntheses,
but with a hitherto unknown structure.