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

Heterometallic polynuclear complexes [{Au(R)₂}₂Cu₂(MeCN)₂]_n (R=C₆F₅, C₆Cl₅) were reacted in THF solution with thioether crowns ligands featuring a different number of S-donor atoms and ring size cavity, and with the quinoline functionalized pendant arm derivatives of tetradentate 12-membered N/S mixed-donor macrocycles. With the latter only ionic compounds of general formula [Cu(L)][Au(R)₂] (L=macrocyclic ligand) were isolated and structurally characterized and none of them featured an Au⋅⋅⋅Cu metallophilic interaction. The optical properties of all complexes were studied experimentally and theoretically via TD-DFT calculations.

Abstract

The reactivity of the heterometallic polynuclear complexes [{Au(R)₂}₂Cu₂(MeCN)₂]_n (R=C₆F₅, C₆Cl₅) 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]aneN₂S₂), 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(C₆F₅)₂], are not luminescent.

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