Experimental and theoretical evidence of the existence of gold(I)···mercury(II) interactions in solution through fluorescence-quenching measurements.

Heteronuclear complexes {[Hg(R)2][Au(R')(PMe3)]2}n (R=R'=C6Cl2F3 (3); R=R'=C6F5 (4); R=C6Cl2F3, R'=C6F5 (5); R=C6F5, R'=C6Cl2F3 (6)) were prepared by the treatment of the corresponding organomercury compounds, [Hg(C6X5)2], with two equivalents of [Au(C6X5)(PMe3)]. Their crystal structures, as determined by using X-ray diffraction methods, display Au···Hg interactions. Although only compound 4 and 5 show luminescence in the solid state, all of these compounds quench the fluorescence of naphthalene in solution. Solution studies of these derivatives suggest a cooperative effect of the gold(I) center in switching on the quenching capabilities of the [Hg(C6X5)2] synthon with naphthalene. Theoretical studies confirmed the quenching ability of the organomercury species in the presence of gold.