Molecular Flexibility in Solvated Crystals of the Dimer, Au 2 (μ-1,2-bis(diphenylphosphino)ethane) 2 I 2 , with Three-Coordinate Gold(I).

We report the ability to trap the dimer Au 2 (μ-dppe) 2 I 2 (dppe is 1,2-bis(diphenylphosphino)ethane) with different separations between the three-coordinate gold ions in crystalline solvates. All of these solvates ((Au 2 (μ-dppe) 2 I 2 ·4(CH 2 Cl 2 ) ( 1 ), Au 2 (μ-dppe) 2 I 2 ·2(CH 2 Cl 2 ) ( 2 ), the polymorphs α-Au 2 (μ-dppe) 2 I 2 ·2(HC(O)NMe 2 ) ( 3 ) and β-Au 2 (μ-dppe) 2 I 2 ·2(HC(O)NMe 2 ) ( 4 ), and Au 2 (μ-dppe) 2 I 2 ·4(CHCl 3 ) ( 5 )) along with polymeric {Au(μ-dppe)I} n · n (CHCl 3 ) ( 6 )) originated from the same reaction, only the solvent system used for crystallization differed. In the different solvates of Au 2 (μ-dppe) 2 I 2 , the Au···Au separation varied from 3.192(1) to 3.7866(3) Å. Computational studies undertaken to understand the flexible nature of these dimers indicated that the structural differences were primarily a result of crystal packing effects with aurophillic interactions having a minimal effect.