6533b7ddfe1ef96bd12748c8

RESEARCH PRODUCT

Enantiomer Separation of Tris(2,2′-bipyridine)ruthenium(II): Interaction of a D3-Symmetric Cation with a C2-Symmetric Anion

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A compound widely used in the separation of the enantiomers of Δ,Λ-[Ru(bipy)3]2+ (bipy = 2,2′-bipyridine) and originally described as “a curious lattice compound” with the formula Δ-[Ru(bipy)3]3[Sb2(R,R-tart)2]2I2·18H2O (tart = tetradeprotonated, carboxyl and hydroxyl, tartaric acid anion) has been crystallographically characterized as this species with a slightly higher degree of hydration (19.5H2O). The crystal lattice has a layered structure in which sheets containing Δ-[Ru(bipy)3]2+ cations and iodide anions alternate with those containing [Sb2(R,R-tart)2]2– anions and water. The role of the iodide ions, which lie in pseudohexagonal cavities formed by the array of three inequivalent but very similar Δ-[Ru(bipy)3]2+ cations, all having their C3 axes directed very close to perpendicular to the sheet, appears to be to favor the orientation of the maximum number of CH units toward the [Sb2(R,R-tart)2]2– entities and to engender formation of (Δ-[Ru(bipy)3]2+)3([Sb2(R,R-tart)2]2–)2 groups optimizing the ass...