ic980372x_si_001.cif (52.49 kB)

The Structures of [24-Pyrimidinium crown-6][Au(CN)2]4(NO3)2·2H2O, [24-Pyrimidinium crown-6][Au(CN)2]6·5H2O, and [16-Pyrimidinium crown-4][Au(CN)2]4·6.5 H2O, in Which Aurophilic Interactions Produce Trimers, Tetramers, and Chains of Au(CN)2- Ions

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posted on 15.10.1998, 00:00 by Roger E. Cramer, David W. Smith, William VanDoorne
The cyclic polypyrimidinium cations [24-pyrimidinium crown-6], [(C6H8N3)6]6+, and [16-pyrimidinium crown-4], [(C6H8N3)4]4+, form colorless salts with the dicyanoaurate(I) anion. [24-Pyrimidinium crown-6][Au(CN)2]4(NO3)2·2H2O (1) crystallizes in the triclinic space group P1̄ (No. 2) with unit cell dimensions a = 10.64(1) Å, b = 10.73(1) Å, c = 13.57(1) Å, α = 71.72(8)°, β = 82.01(9)°, γ = 83.90(9)°, and V = 1455(3) Å3. [24-Pyrimidinium crown-6][Au(CN)2]6·5H2O (2) crystallizes in the triclinic space group P1̄ (No. 2) with unit cell dimensions a = 11.780(5) Å, b = 12.064(4) Å, c = 13.268(4) Å, α = 102.56(1)°, β = 112.14(1)°, γ = 101.82(1)°, and V = 1617(1) Å3. [16-Pyrimidinium crown-4][Au(CN)2]4·6.5H2O (3) crystallizes in the monoclinic space group C2/c (No. 15) with unit cell dimensions a = 39.50(2) Å, b = 13.160(7) Å, c = 17.83(7) Å, β = 90.66(3)°, and V = 9268(39) Å3. Structures 1 and 3 contain similar centrosymmetric zigzag tetramers of Au(CN)2- anions, with a terminal Au−Au distance of 3.271(4) Å and an Au−Au central distance of 3.492(5) Å for structure 1, as compared to 3.155(7) and 3.501(7) Å, respectively, for 3. Structure 2 contains a nearly linear trimer of Au(CN)2- ions with Au−Au distances of 3.175(1) and 3.234(1) Å. In addition to the Au(CN)2- tetramer, structure 3 also contains an infinite chain of Au(CN)2- anions consisting of repeating tetrameric units spiraling along a 2-fold axis with internal Au−Au distances of 3.128(3), 3.220(4), and 3.274(5) Å and an Au−Au distance of 3.698(4) Å between tetrameric units.

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