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The reaction of the polymers [Au2Cu2(C6X5)4(NCMe)2]n (X = Cl (1), F (2)) with the aromatic N-donor ligand pyridazine in different molar ratios gives rise to new Au(i)/Cu(i) heterometallic complexes [AuCu(C6Cl5)2(μ2-C4H4N2)(NCMe)]2 (3), [AuCu(C6X5)2(μ2-C4H4N2)(C4H4N2)]2 (X = Cl (4), X = F (6)) and [Cu2(μ2-C4H4N2)3(NCMe)2][Au(C6F5)2]2 (5). In all cases, the close proximity of the donor atoms in the diazine ligand leads to discrete molecules where two copper centres are connected by two or three bridging pyridazine ligands. In this way, focusing on the number of bridging ligands present in the molecules, unsupported closed-shell Au(i)…Cu(i) (with two bridging pyrazine ligands) or weak Cu(i)…Cu(i) interactions (with three bridging pyridazines) have been observed. None of these pyridazine derivatives is luminescent, which is probably related to the absence of aurophilic contacts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Reaction of [Au(C6F5)(tht)] (tht = tetrahydrothiophene) with 2,2′:6′,2″-terpyridine (terpy) leads to complex [Au(C6F5)(η¹-terpy)] (1). The chemical oxidation of complex (1) with 2 equiv of [N(C6H4Br-4)3](PF6) or using electrosynthetic techniques affords the Au(III) complex [Au(C6F5)(η³-terpy)](PF6)2 (2). The X-ray diffraction study of complex 2 reveals that the terpyridine acts as tridentate chelate ligand, which leads to a slightly distorted square-planar geometry. Complex 1 displays fluorescence in the solid state at 77 K due to a metal (gold) to ligand (terpy) charge transfer transition, whereas complex 2 displays fluorescence in acetonitrile due to excimer or exciplex formation. Time-dependent density functional theory calculations match the experimental absorption spectra of the synthesized complexes. In order to further probe the frontier orbitals of both complexes and study their redox behavior, each compound was separately characterized using cyclic voltammetry. The bulk electrolysis of a solution of complex 1 was analyzed by spectroscopic methods confirming the electrochemical synthesis of complex 2. [ABSTRACT FROM AUTHOR]

The reactions of 4(dimethylamino)pyridine (DMAP) with the gold(i) precursors [AuR(tht)] (R = C6F5, C6Cl2F3 or C6Cl5; tht = tetrahydrothiophene) lead to complexes [AuR(DMAP)] (R = C6F5 (1), C6Cl2F3 (2) or C6Cl5 (3)). X-ray diffraction studies of the complexes reveal the presence of discrete molecules in which aurophilic contacts are absent, with π-stacking (1) or hydrogen bond (2) interactions being responsible for the supramolecular arrangements found in the solid state. All complexes display fluorescence in solution in solvents of different polarities such as toluene, chloroform or acetonitrile. In all cases the emission energy is similar to the low-energy Twisted Intramolecular Charge Transfer (TICT) emission of free DMAP. TDDFT calculations confirm that the fluorescence of complexes 1–3 arises from the ICT excited state of bonded DMAP in which a 90° distortion of the pyridine ring and –NMe2 planes is observed. Model calculations based on experimental parameters show a higher degree of polarization of DMAP upon coordination to Au(i) organometallic fragments. [ABSTRACT FROM AUTHOR]

The reaction of 1,4-bis(2′-pyridylethynyl)benzene (L) with [{Au(C6X5)2}Tl]n affords new heterometallic AuI/TlI complexes with different stoichiometries, structural arrangements and optical properties depending on the halogens present in the aryl group. The chlorinated derivative [{Au(C6Cl5)2}Tl(L)]n (1) displays polymeric chains built thanks to unsupported Au…Tl interactions and bridging bidentate ligands between adjacent chains, while in the fluorinated species [{Au(C6F5)2}2Tl2(L)2]n (2), also containing N-donor bridging ligands and Au…Tl contacts, polymerization occurs via Tl…Caryl non-bonding interactions between neighbouring molecules. The optical properties of 1 and 2 have been studied experimentally and theoretically, concluding that the luminescence of 1 in the solid state has its origin in the Au…Tl interactions, and that the Tl…Caryl interactions in 2 favour a non-radiative deactivation pathway that avoids luminescence. The strength of the non-bonding interactions present in 1 has also been theoretically studied at the HF and MP2 levels, revealing the metallophilic contact as the strongest one. [ABSTRACT FROM AUTHOR]

Highlights: [•] Complex [{Au(C6Cl5)2}Ag([9]aneS3)]2 displays a [Ag]+–[Au]−–[Au]−–[Ag]+ sequence. [•] Ab initio calculations are used for the study of the nature of the interactions in the Au–Ag complex. [•] Metallophilic Au(I)⋯Ag(I) and C ipso ⋯Ag(I) interactions have an ionic plus a dispersive origin. [•] Au(I)⋯Au(I) and π-stacking interactions mainly arise from dispersive forces. [ABSTRACT FROM AUTHOR]

Tetrahedral Au¹ complexes [L3Au(SnCl3)l (L = PMe3 (1), PMe2Ph (2), PMePh2 (3), and PPh3 (4)) were prepared by treatment of the [(tht)Au(SnCl3)l (tht = tetrahydrothiophene) complex with three equivalents of the corresponding tertiary phosphine. The crystal structures of complexes 1-4 have been determined through X-ray diffraction studies showing, in all cases, [SnCl3]-fragments covalently bonded to the corresponding [Au(PR3)3]+ units, which leads to a tetrahedral coordination environment for gold. Complexes 3 and 4 show phosphorescence in the solid state at room temperature and 77 K that is largely redshifted relative to the free [Au(PR3)3]+ and [SnCl3]- counterparts. Correlated MP2, SCS-MP2, and ONIOM MP2/UFF calculations suggest a largely distorted lower triplet excited state (T,) for each model system. The AuP3+ moiety is distorted leading to a T-shape, whereas the SnCl3- unit is left almost unaltered. Molecular orbital and population analysis suggest that the emission of these tetrahedral Au1 complexes arises from a ³MC transition slightly perturbed by the SnCl3- fragment. [ABSTRACT FROM AUTHOR]

The polymeric Au/Tl compounds [{Au(C6X5)2}Tl]n (X = Cl, F) react with the crown thioethers 1,4,7-trithiacyclononane ([9]aneS3), 1,5,8,11-tetrathiacyclotetradecane ([14]aneS4), and 1,4,7,10,13,16,19,22-octathiacyclotetracosane ([24]aneS8) in an appropriate molar ratio to afford [{Au(C6X5)2}Tl(L)]2 [L = [9]aneS3, X = Cl (1), F (4); L = [14]aneS4, X = Cl (2), F (5)], [{Au(C6Cl5)2}2Tl2([24]aneS8)]n (3) or [{Au(C6F5)2}2Tl2([24]aneS8)] (6). X-ray diffraction studies of 3, 4 and 6 reveal polymeric (3) or tetranuclear (4, 6) structures formed via Tl–S bonds and Au…Tl or Au…Tl and Au…Au contacts. All the complexes are luminescent in the solid state, but not in solution, where the metal–metal interactions, which are responsible for the luminescence, are no longer present. DFT calculations on representative model systems of complexes 3, 4 and 6 have also been carried out in order to determine the origin of the electronic transitions responsible for their optical properties. [ABSTRACT FROM AUTHOR]

Abstract: The heteropolynuclear complexes [AuTl(C6X5)2] n (X=F, Cl) react with dimethylsulfoxide (DMSO) in different molar ratios leading to products of stoichiometry [Tl2{Au(C6F5)2}2{μ-DMSO}3] n (1), and [Tl2{Au(C6Cl5)2}2{μ-DMSO}2] n (2). These complexes have been structurally characterized and can be viewed as extended linear chains built with Tl–Au–Tl units in which the thallium atoms are bridged by the oxygen atoms of DMSO ligands. Additional [Au(C6X5)2]− fragments interact with one or two thallium centres, respectively, giving rise to two different types of metal–metal interactions in each molecule. Both of them show a strong luminescence in solid state and complex 2 also in solution. The thallium–thallium interaction in this complex is considered to be the responsible of its luminescence, which remains in solution. [Copyright &y& Elsevier]

Abstract: Gold(I) compounds have several potential roles in biologically related chemistry. The relatively low toxicity of gold and its lability allows human consumption of drugs formed with this element. Trinuclear and tetranuclear clusters look particularly interesting because of the strong basicity of the gold(I) centers in these molecules. Future studies are expected to lead to interesting new bio-related observations. The ability of gold(I) compounds to interact with themselves aurophilically and with other heavy element ions has produced spectroscopic properties which are sensitive to volatile organic compounds (VOCs) and other molecular interactions. Thus bio-applicability for sensing toxic components appears reasonable. [Copyright &y& Elsevier]