Selective formation of gold(I) bis-phospholane macrocycles, polymeric chains, and nanotubes

A series of highly flexible bis-phospholane ligands 3a-g with 5-11 methylene groups in the backbone was synthesized and fully characterized by mass spectrometry and NMR ((1)H, (13)C, (31)P) and IR spectroscopy. Gold bis-phospholane macrocycles containing 16 ([Au2Cl2(μ-3a)2], 4), 20 ([Au2Cl2(μ-3c)2], 5), 24 ([Au2Cl(μ-3e)2]Cl, 6), and 28 ([Au2Cl2(μ-3g)2], 7) atoms in the ring were obtained in one step from [AuCl(tht)] (tht = tetrahydrothiophene) and 3a,c,e,g in excellent yield. In addition, three polymers resulting from aurophilic interactions, i.e., zigzag chains in [Au2Cl2(μ-3b)]x (8) and nanotubes in [Au2Cl2(μ-3d)]x (9) and [Au2Cl2(μ-3f)]x (10), with Au···Au distances of 309.41(2), 330.24(6), and 335.82(3) pm, respectively, were obtained. Halide abstraction of 4-7 with AgBF4 led to macrocycles [Au2(μ-3a)2](BF4)2 (11), [Au2(μ-3c)2](BF4)2 (12), [Au2(μ-3e)2](BF4)2 (13), and [Au2(μ-3g)2](BF4)2 (14). In 12, the monomers are connected by strong aurophilic interactions (Au···Au 296.57(1) pm) in the solid state with formation of a polymeric chain. All complexes were fully characterized by NMR ((1)H, (13)C, (31)P) and IR spectroscopy, mass spectrometry, and X-ray diffraction.