Aurophilic Interactions in Three-Coordinate Gold(I) Complexes with C‑Clamp-like Structures

Compounds containing three-coordinate gold(I) centers
that engage
in aurophilic interactions have been obtained by using bridging diphosphines.
Colorless crystals of [(μ-dppm){Au(bipy)}2](PF6)2 (1) and [(μ-dppe){Au(bipy)}2](BF4)2 (2) (where dppm
is bis(diphenylphosphino)methane), dppe is 1,2-bis(diphenylphosphino)ethane
and bipy is 2,2′ bipyridine have been obtained by a one pot
method combining dppm (or dppe) with (tht)AuCl (tht is tetrahydrothiophene),
bipy, and ammonium hexafluorophosphate in chloroform. The cations
in [(μ-dppm){Au(bipy)}2](PF6)2 (1) and [(μ-dppe){Au(bipy)}2](BF4)2 (2) have c-clamp-like structures
with Au–Au bond lengths of 3.0903(6) and 3.249(1) Å, respectively.
Unlike the situation in many two-coordinate gold(I) complexes, where
aurophilic interactions induce luminescence, crystals of complexes
(1) and (2) are not luminescent at room
temperature or at 90 K.