Design and understanding of solid-state and crystalline materials
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Article citation: Nicholas A. Barnes, CrystEngComm, 2010, DOI: 10.1039/b917245a
Can the solid state structures of the dihalogen adducts R3EX2 (E = P, As; R = alkyl, aryl; X = Br, I) with the molecular spoke geometry be considered good mimics of the gold(I) systems [(R3E)AuX] (E = As, P; R = alkyl, aryl; X = Cl, Br, I)?
Nicholas A. Barnes, Kevin R. Flower, Saad A. Fyyaz, Stephen M. Godfrey, Alan T. McGown, Philip J. Miles, Robin G. Pritchard and John E. Warren
The solid-state structures of compounds of the type R3EX2 and [(R3E)AuX] (R = alkyl, aryl, E = As, P, X = Cl, Br, I) have been compared on the basis that they have similar molecular shape and volume with a view to determine whether this is a good approach to understand the formation of aurophilic interactions. To aid in the discussion the new compounds Ph2(C6H5–C6H4)P 1, Ph2(C6H5–C6H4)PI21a, [Ph2(C6H5–C6H4)PAuX] (X = Cl 2a, Br 2b, I 2c) and [(LAu)–C6H4–2–OMe] (L = PPh33a, PCy33b; PPh2-1-naphthyl 3c; PPh2–2–MeO–C6H43d) and [(LAu)–C6H3–2,5–(OMe)2] (L = PPh34a, PCy34b; PPh2-1-naphthyl 4c; PPh2–2–MeO–C6H44d, which have all been fully spectroscopically characterised and for 1a, 2a–c, 3a and 3c by X-ray crystallography, have been synthesised. It is found that in some cases the group 15 dihalogen adducts mimic the solid state structures of the gold halide complexes extremely well indicating the packing requirements of the ligand are dominant. In many other cases there are significant differences and these differences shed light on why it is difficult to predict with certainty the presence of an Au
Au contact. It also appears that complexes with an Au–I bond are most likely to form an AuAu contact as the Au–I bond is the weakest hydrogen bond acceptor.
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