Aurophilic attractions: one cation, [Au{C(OMe)NMeH}2]+, but three different structural arrangements in the solid state salts

Three salts of the cation [Au{C(OMe)NMeH}(2)](+), formed by protonation of the solvoluminescent gold(I) trimer [Au-3(MeN=COMe)(3)], have been prepared and spectroscopically and structurally characterized. Each crystallizes as a unique form with varying aurophilic interactions between the linear, two-coordinate cations. Thus, the chloroform solvate, [Au{C(OMe)NMeH}(2)][C7Cl2NO3]. CHCl3, (where [C7Cl2NO3](-) is an anion obtained by hydrolysis of 2,3-dichloro-4,5-dicyano-1,4-benzoquinone, DDQ), contains the cation as an isolated monomer, while unsolvated [Au{C(OMe)NMeH}(2)][C7Cl2NO3] contains pairs of cations that are linked by a single Au . . . Au interaction with a 3.1955(3) Angstrom separation between the gold centers. In [Au{C(OMe)NMeH}(2)][O2CCF3] the cations associate to form infinite, nearly linear (Au . . . Au . . . Au angle, 172.209(7)degrees) chains that have the gold centers only 3.27797(15) Angstrom apart. The luminescent behavior of [Au{C(OMe)NMeH}(2)][O2CCF3] is reported.