Surprising discoveries on the way to an old compound: four transient iodido antimonates

Abstract

During the synthesis of the literature-known iodido antimonate [Cu(MeCN)₄]₄[Sb₃I₁₁]₂ (MeCN = acetonitrile), four transient compounds, [Cu(MeCN)₄]₄[Sb₆I₂₂]·2MeCN (1), [Cu(MeCN)₄]₄[Sb₇I₂₅]·MeCN (2), [Cu(MeCN)₄]₄[Sb₁₀I₃₄] (3) and [Cu(MeCN)₄]₄[Sb₈I₂₈] (4), were identified. The compounds appeared within hours or days and subsequently re-dissolved in the mother liquor, leading to [Cu(MeCN)₄]₄[Sb₃I₁₁]₂ as the final product. Single crystal X-ray analysis showed that all four compounds feature unprecedented anion motifs.