Double Jahn–Teller Distortion in AuGe Complexes Leading to a Dual Blue–Orange Emission

Abstract

The tetrahedral AuI complexes [Au(GeCl3)L3] (L=PMe3 (1), PMe2Ph (2), PMePh2 (3), PPh3 (4)) were synthesized by in situ treatment of the [Au(GeCl3)(tht)] complex with three equivalents of the corresponding tertiary phosphine. The crystal structures of complexes 1 and 3 have been determined through X‐ray diffraction studies and show [GeCl3]− fragments bonded to the corresponding [Au(PR3)3]+ units through covalent bonds, leading to a tetrahedral coordination environment for gold. Complexes 3 and 4 show dual phosphorescence in the solid state at 77 K and, in the case of complex 4, an interesting room‐temperature mechanochromism effect is observed. Correlated MP2, SCS‐MP2, SCS‐CC2, and ONIOM MP2/UFF calculations suggest the existence of two largely distorted and thermally connected triplet excited states (T1 and T2) for a model system of complex 4. The AuP3+ moiety can be distorted in two different planes leading to the two triplet excited states T1 and T2, leaving the GeCl3− unit almost unaltered. The emissions of these phosphorescent AuIGeII complexes is mainly ascribed to a metal (gold)‐centered (3MC) transition with some contribution from the [GeCl3]− fragments.

Optical Properties in Heteronuclear Gold(I)/Silver(I) Complexes of Aliphatic Mixed‐Donor Macrocycles Featuring Metallophilic Interactions

“…and described several years ago [27] . In addition, we [28] and others have previously reported such mechanochromic behaviour for many gold based complexes, including perhalophenyl derivatives as it is in our case [29–33] …”

“…and described several years ago. [27] In addition, we [28] and others have previously reported such mechanochromic behaviour for many gold based complexes, including perhalophenyl derivatives as it is in our case. [29][30][31][32][33] In order to support the observed changes of the PXRD profile of 3 after grinding, we have represented the corresponding Williamson-Hall plots (see Figure S1 in SI).…”

“…In this respect, the luminescence properties of many heteronuclear gold(I) complexes are currently considered of great interest because they are closely related to their structural features, in particular, to the intermolecular interaction patterns in the crystal lattice based on aurophilic, Au(I)•••Au(I), and/or metallophilic Au(I)•••M interactions [M = transition and posttransition closed-shell metal ions such as Ag(I) and Tl(I)]. [4][5][6][7][8][9][10][11] In fact, solid-state phase transitions in these complexes, in response to external stimuli (grinding, but also heating, pressure and interaction with a solvent), which can involve the alteration of the metallophilic interactions and/or molecular arrangements, are generally associated to luminescence emission changes. [4][5][6][7][8][9][10][11][12][13][14][15] Recently, we have considered macrocyclic ligands of different ring size and nature/number of donor atoms to support Au(I)•••M(I) (M = Ag, Tl) metallophillic interactions in the formation of heteronuclear complexes starting from organometallic gold(I) polymeric complexes [{Au(C 6 X 5 ) 2 }M] n (M = Ag(I), Tl(I); X = Cl, F) in low polar solvents (toluene, tetrahydrofuran (THF)).…”

“…[4][5][6][7][8][9][10][11] In fact, solid-state phase transitions in these complexes, in response to external stimuli (grinding, but also heating, pressure and interaction with a solvent), which can involve the alteration of the metallophilic interactions and/or molecular arrangements, are generally associated to luminescence emission changes. [4][5][6][7][8][9][10][11][12][13][14][15] Recently, we have considered macrocyclic ligands of different ring size and nature/number of donor atoms to support Au(I)•••M(I) (M = Ag, Tl) metallophillic interactions in the formation of heteronuclear complexes starting from organometallic gold(I) polymeric complexes [{Au(C 6 X 5 ) 2 }M] n (M = Ag(I), Tl(I); X = Cl, F) in low polar solvents (toluene, tetrahydrofuran (THF)). [16][17][18][19][20][21][22][23][24] The results achieved so far clearly proved a great versatility and potentiality of these ligands, in particular, thioether crowns and mixed thia-aza macrocycles also featuring aromatic moieties, in determining unusual structural archetypes, metal ion dispositions and intermolecular Au(I)•••M(I) interaction patterns in the isolated Au(I)/Ag(I) and Au(I)/Tl(I) heteronuclear complexes.…”

“…In this respect, the luminescence properties of many heteronuclear gold(I) complexes are currently considered of great interest because they are closely related to their structural features, in particular, to the intermolecular interaction patterns in the crystal lattice based on aurophilic, Au(I)⋅⋅⋅Au(I), and/or metallophilic Au(I)⋅⋅⋅M interactions [M=transition and post‐transition closed‐shell metal ions such as Ag(I) and Tl(I)] [4–11] . In fact, solid‐state phase transitions in these complexes, in response to external stimuli (grinding, but also heating, pressure and interaction with a solvent), which can involve the alteration of the metallophilic interactions and/or molecular arrangements, are generally associated to luminescence emission changes [4–15] …”