Heteronuclear Gold(I)-Copper(I) Complexes with Thia- and Mixed Thia-Aza Macrocyclic Ligands: Synthesis, Structures and Optical Properties.

Abstract

The reactivity of the heterometallic polynuclear complexes [{Au(R)2 }2 Cu2 (MeCN)2 ]n (R=C6 F5 , C6 Cl5 ) with the thioether crowns 1,4,7-trithiacyclononane (L1, [12]aneS3 ), 1,4,8,11-tetrathiacyclododecane (L2, [14]aneS4 ), 1,4,7,10,13,16,19,22-octathiacyclotetracosane (L3, [24]aneS8 ), and the quinoline functionalized pendant arm derivatives of the 12-membered mixed-donor macrocycles 1-aza-,4,7,10-trithiacyclododecane ([12]aneNS3 ) and 1,7-diaza-4,10-dithiacyclododecane ([12]aneN2 S2 ), L4 and L5, respectively, was investigated in THF solution. While with L4 and L5 only ionic compounds of general formulation [Cu(L)][Au(R)2 ] were isolated and structurally characterized (none of them featuring Au⋅⋅⋅Cu interactions), with L1-L3, beside similar ionic compounds, some heteronuclear complexes of general formulation [{Au(R)2 }{Cu(L)}] and featuring Au⋅⋅⋅Cu interactions were also obtained. All of them display rather unusual non-classical C-H⋅⋅⋅Au hydrogen interactions. The complexes display in the solid state different optical properties related to their structures, which have been studied experimentally and theoretically via TD-DFT calculations. In particular, all compounds of the type [{Au(R)2 }{Cu(L)}] featuring Au⋅⋅⋅Cu metallophilic interactions display luminescence in the solid state both at room temperature (RT) and at 77 K. On the contrary, ionic compounds of general formulation [Cu(L)][Au(R)2 ], except [Cu(L4)][Au(C6 F5 )2 ], are not luminescent.