Gold(I)−Gold(III) Interactions in Polynuclear Sulfur-Centered Complexes. Synthesis and Structural Characterization of [S(Au2dppf){Au(C6F5)3}] and [{S(Au2dppf)}2{Au(C6F5)2}]OTf (dppf = 1,1‘-Bis(diphenylphosphino)ferrocene)

The reactions of [S(Au 2 dppf)] (dppf = 1,1‘-bis(diphenylphosphino)ferrocene) with the gold(III) precursors [Au(C 6 F 5 ) 3 (OEt 2 )] and [Au(C 6 F 5 ) 2 (OEt 2 ) 2 ]OTf afford the mixed-valence complexes [S(Au 2 dppf){Au(C 6 F 5 ) 3 }] ( 1 ) and [{S(Au 2 dppf)} 2 {Au(C 6 F 5 ) 2 }]OTf ( 2 ). The crystal structures of these derivatives have been determined and show short gold(I)−gold(III) contacts of 3.404(1) Å in 1 and 3.2195(8) and 3.3661(10) Å in 2 . DFT calculations, including correlation and relativistic corrections, show that in these compounds where sulfur bridges three gold atoms it prefers to become pyramidal rather than planar, and Au(I)−Au(III) distances are indicative of a possible weak interaction. EH calculations suggest that such interaction is similar in origin to the well-studied Au(I)−Au(I) weak interactions and that it may occur in some real compounds.