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Updated: Dec 22, 2025
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Charge-Separation-Type Ionic Crystals with Mixed AuI4CoIII2 and AuI4NiIICoIII Hexanuclear Complexes
Rycce S Pratikha1, Tatsuhiro Kojima1, Naoto Kuwamura1
1Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Abstract:
Treatment of a digold(I) metalloligand, [AuI2(dppe)(d-Hpen)2] (H2LAu; d-H2pen = d-penicillamine, dppe = 1,2-bis(diphenylphosphino)ethane), with a 1:1 mixture of Co(OAc)2 and Ni(OAc)2 under aerobic conditions resulted in the formation of three types of hexanuclear complexes: [CoIII2(LAu)2]2+, [NiIICoIII(LAu)2]+, and [NiII2(LAu)2]. The addition of NaNO3, M1NO3 (M1 = K, Rb, Cs), and M2(NO3)2 (M2 = Ca, Sr, Ba) to the reaction mixture led to co-crystallization of [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ as a solid solution to form the charge-separation (CS)-type ionic crystals 1, 1, and 1, respectively, while [NiII2(LAu)2] independently crystallized as a single species (2). In 1, [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ cations assemble in a 1:2 ratio to form a cationic supramolecular octahedron accommodating 4 H3O+ ions, while 10 nitrate ions are packed in each hydrophilic tetrahedral interstice of the crystal to form an anionic adamantane cluster. The overall structures of 1 and 1 are very similar to that of 1, having a CS-type structure composed of cationic supramolecular octahedra with a +12 charge and anionic inorganic clusters with a -10 charge. However, 1 contains M1 ions in place of the H3O+ ions in 1, and furthermore, a novel rhombic dodecahedron cluster composed of 14 nitrate ions, which encapsulates two M2 ions, is formed in each hydrophilic tetrahedral interstice in 1.
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