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The polymeric linear chain [AuTl(C 6 Cl 5 ) 2 ] n reacts with three terpyridine-type ligands substituted with thiophene groups containing N-donor centres in different relative positions (L1, L2 and L3), leading to the Au(I)/Tl(I) complexes [AuTl(C 6 Cl 5 ) 2 (L1)] n (1), [{AuTl(C 6 Cl 5 ) 2 } 2 (L2)] n (2) and [AuTl(C 6 Cl 5 ) 2 (L3)] n (3). X-Ray diffraction studies reveal that L1 acts as a chelate, while L2 and L3 act as bridging ligands, resulting in different coordination indexes for the thallium(I) centre. These structural differences strongly influence their optical properties, and while compounds 2 and 3 emit near the limit of the visible range, complex 1 emits in the infrared region. DFT calculations have also been carried out in order to determine the origin of the electronic transitions responsible for their optical properties.

The reaction among [Au 2 Ag 2 (C 6 F 5 ) 4 (OEt 2 ) 2 ] n , PbCl 2 and terpyridine leads to the polymeric complex [{Au(C 6 F 5 ) 2 } 2 {Pb(terpy)}] n (1). Its crystal structure reveals potential voids close to the lead centres large enough to hold different molecules. The availability of these free sites allows complex 1 to act as a VOC sensor. Thus, when 1 is exposed to different solvent vapours such as acetonitrile, toluene or THF, variations in its solid appearance and its photophysical properties are observed as a consequence of the formation of the new polymorphs [{Au(C 6 F 5 ) 2 } 2 {Pb(terpy)(CH 3 CN) 2 }] n (2), [{Au(C 6 F 5 ) 2 } 2 {Pb(terpy)}] n ·Tol (3) and [{Au(C 6 F 5 ) 2 } 2 {Pb(terpy)(THF)}] n ·THF (4). Each polymorph displays a different emission energy depending on its structure and the presence of metallophilic interactions. In addition, the reversible solvent molecule exchange allows the tuning of the luminescence emissions in the greenish yellow-red range. DFT and TD-DFT calculations were performed to explain the origin of the luminescence of all these complexes.

The existence of aurophilic gold(III)⋯gold(III) interactions has for a long time been neglected due to structural arguments and comparison with the aurophilicity of gold(I) compounds. We show with calculations at the CCSD(T) level of theory that the [Au III (CH 3 ) 3 (NH 3 )] 2 dimer has a metallophilic dispersion interaction between the gold(III) atoms of 10.5 kJ mol -1 . The aurophilic interaction is illustrated by topological QTAIM calculations and IRI analysis.

1,4,7-Triazacyclononane (TACN) has been used for the first time to support Au(i)M [M = Tl(i), Ag(i)] metallophilic interactions in the formation of heteronuclear gold(i) complexes having luminescence properties. The compounds {[{Au(C6Cl5)2}Tl(TACN)]2}n (1), [{Au(C6F5)2}Tl(TACN)] (2), [{Au(C6Cl5)2}Ag(TACN)] (3), and [{Au(C6F5)2}{Ag(TACN)}2Au(C6F5)2] (4) have been synthesized by reacting TACN and the polymeric starting organometallic gold(i) compounds [{Au(C6X5)2}M]n (M = Ag(i), Tl(i); X = Cl, F) in a 1 : 1 molar ratio, in THF. 1, 3 and 4 have also been structurally characterized and their optical properties explained on the basis of their structural features with the support of TD-DFT calculations.

The ionic complex [Au( 9 N-adenine)(PMe 3 )](CF 3 CO 2 ) (1) displays a supramolecular structure built up through ionic, π-stacking, C-HO, C-HN and C-HAu interactions. Ab initio calculations permit the characterization of the nature of these interactions. Complex 1 is luminescent in the solid state at 77 K. This complex forms a hydrometallogel consisting of straight molecular nanowires, which is responsive to thermal and mechanical stimuli. The gel has also been studied by rheological oscillatory experiments.

A temperature-controlled self-assembly process in a solution of [Ag(terpy)]nn+ and [Au(C6F5)2]- units has been performed. For this, the crystallisation of the complex [{Au(C6F5)2}Ag(terpy)]n under the same experimental conditions, changing only the temperature, allows the synthesis of polymorphs [{Au(C6F5)2}2Ag2(terpy)2]n (2a) at 298 K and [{Au(C6F5)2}Ag(terpy)]n (2b) at 280 K. The X-ray diffraction studies previously reported for 2a revealed a polymeric structure with an unusual + + - - + + - - charge sequence, whereas for polymorph 2b, a more classical + - + - disposition has been obtained. The conversion of one polymorph into the other can be achieved by simple dissolution of one of them and by recrystallisation at the corresponding temperature. The mechanism of the formation of each polymorph is proposed in view of their 1H NMR, 1H-PGSE NMR and molar conductivity measurements.

Following an acid-base strategy, based on the reaction between gold(i) basic fragments and acid silver salts, it is possible to obtain heterometallic polymers of the general formula [Au 2 Ag 2 (R) 4 (L) 2 ] n (R = C 6 Cl 2 F 3 ; L = pyrimidine). Using this new heterometallic complex [Au 2 Ag 2 (C 6 Cl 2 F 3 ) 4 (pym) 2 ] n (1) as a starting material, and a good coordinating solvent such as acetonitrile, it is possible to modify the arrangement of the ligands connected to the silver centres and to obtain three different tetranuclear Au 2 Ag 2 building blocks leading to the new polymer [Au 6 Ag 6 (C 6 Cl 2 F 3 ) 12 (μ 2 -pym) 2 (NCMe) 6 ] n (2). Both complexes display very intense luminescence emission. Structural, experimental and computational studies have been carried out in order to identify the origin of these properties and the factors that can affect them, such as, the presence of metallophilic interactions as well as different coordination environments for the metallic centres.

The reaction of the polymers [Au 2 Cu 2 (C 6 X 5 ) 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(C 6 Cl 5 ) 2 (μ 2 -C 4 H 4 N 2 )(NCMe)] 2 (3), [AuCu(C 6 X 5 ) 2 (μ 2 -C 4 H 4 N 2 )(C 4 H 4 N 2 )] 2 (X = Cl (4), X = F (6)) and [Cu 2 (μ 2 -C 4 H 4 N 2 ) 3 (NCMe) 2 ][Au(C 6 F 5 ) 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.

Among the coinage metal complexes displaying luminescent properties, those bearing C-donor aryl ligands have an increasing part in the chemistry of these metals. These types of ligands confer a high kinetic and thermodynamic stability on the complexes, but they can also be involved in the photoluminescent behaviour of the complexes. The development of new aryl-containing complexes of group eleven metals, the study of their photoluminescent properties and their related properties and applications are discussed in this perspective. Among these, luminescent gold(i) and gold(iii) compounds are being intensively used for the development of new properties with potential applications such as, for instance, electroluminescence, triboluminescence, mechanochromism, aggregated induced emissions, quenching, luminescent liquid crystals, low molecular weight gelators and photocatalysts, among others.

The preparation of homoleptic heterometallic complexes still remains a challenge. Herein, we report the synthesis and characterization of [Au(PMe3)2][{AuHg2(o-C6F4)3}{Hg3(o-C6F4)3}] (), a gold-mercury homoleptic metallacycle. The crystal structure of displays two [Hg2M(o-C6F4)3] (M = Au(I), Hg(II)) units linked through a short AuHg contact of 3.097(2) Å, the strongest unsupported Au(I)Hg(II) interaction described to date. Theoretical calculations quantify the interaction between the trimetalic units as -199 kJ mol(-1), a surprisingly strong value.

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.

The reaction of 1,4-bis(2'-pyridylethynyl)benzene (L) with [{Au(C6X5)2}Tl]n affords new heterometallic Au(I)/Tl(I) 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 () displays polymeric chains built thanks to unsupported AuTl interactions and bridging bidentate ligands between adjacent chains, while in the fluorinated species [{Au(C6F5)2}2Tl2(L)2]n (), also containing N-donor bridging ligands and AuTl contacts, polymerization occurs via TlCaryl non-bonding interactions between neighbouring molecules. The optical properties of and have been studied experimentally and theoretically, concluding that the luminescence of in the solid state has its origin in the AuTl interactions, and that the TlCaryl interactions in favour a non-radiative deactivation pathway that avoids luminescence. The strength of the non-bonding interactions present in has also been theoretically studied at the HF and MP2 levels, revealing the metallophilic contact as the strongest one.

Reactions between [Au(C6Cl2F3)(tht)] and P,N-donor bridging ligands of the type PPh2py and (PPh2)2phen lead to the homonuclear gold complexes [Au(C6Cl2F3)(PPh2py)] (1) and [Au2(C6Cl2F3)2{(PPh2)2phen}] (2). Subsequent addition of [Cu(CH3CN)4](BF4) leads to the formation of the corresponding gold-copper heterometallic complexes [Au2Cu(C6Cl2F3)2(PPh2py)2](BF4) (3) and [Au2Cu(C6Cl2F3)2{(PPh2)2phen)}(CH3CN)](BF4) (4). The four complexes have been structurally characterized and are luminescent. The gold precursors show emissions arising from metal-perturbed intraligand transitions. The heterometallic complexes show a red shift of the emissions that is proposed to arise from an admixture of IL (intraligand) and MLCT (metal-to-ligand-charge-transfer) transitions. DFT and TD-DFT calculations agree well with these results.

Ultrasmall gold nanoparticles (Au UNPs) represent a unique class of nanomaterials making them very attractive for certain applications. Herein, we developed an organometallic approach to the synthesis of Au UNPs stabilized with the C18H37-NHC ligand by the solvent free thermolysis of [RMIM][Au(C6F5)2] () or [Au(C6F5)(RNHC)] () (with R = C18H37-), by controlling the reactivity of pentafluorophenyl ligands as deprotonating or reductive elimination agents; Au UNPs can be achieved by solvent free thermolysis. Pentafluorophenyl Au(i) complexes and are synthesized from the corresponding ionic and neutral precursors. The presence of long alkyl chain imidazolium or carbene species in the complexes makes them to behave as isotropic liquids at moderate temperatures. The use of multinuclear NMR allows the description of the mechanism of formation of the UNPs as well as the surface state of the UNPs.

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 AuTl or AuTl and AuAu 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.

Complex [Au{4-C(6)F(4)(4-C(6)BrF(4))}(tht)] reacts with diphosphines (L-L) such as bis(diphenylphosphino)methane (dppm) or 1,2-bis(diphenylphosphino)benzene (dppb) in a 2 : 1 molar ratio in dichloromethane, leading to neutral products of stoichiometry [(Au{4-C(6)F(4)(4-C(6)BrF(4))})(2)(μ-L-L)] (L-L = dppm (1), dppb (2)). In the crystal structure of complex 2 short Au···Au interactions of 2.9367(5) and 2.9521(5) Å appear. This complex displays an orange emission, which is assigned to arise from a charge transfer transition from a metal centered Au-Au orbital to an orbital located at the diphosphine ligand. Addition of silver trifluoroacetate to these complexes in a 1 : 1 or a 2 : 1 molar ratio generates polymeric heterometallic gold-silver compounds of stoichiometry [Ag(2)Au(2){4-C(6)F(4)(4-C(6)BrF(4))}(2)(CF(3)CO(2))(2)(μ-L-L)](n) (L-L = dppm (3), dppb (4)), which confirms the capability of the neutral [(Au{4-C(6)F(4)(4-C(6)BrF(4))})(2)(μ-diphosphine)] units to act as electron density donors when treated with a Lewis acid substrate. These heterometallic derivatives show blue emissions indicating large HOMO-LUMO band gaps, due to the stabilization that the gold-based HOMO orbitals suffer when the electron withdrawing silver trifluoroacetate fragments interact with them.

The synthesis, structural characterization and the study of the photophysical properties of complexes [AuCu(C6F5)2(N[triple bond]C-CH3)2] 1, [AuCu(C6F5)2(N[triple bond]C-Ph)2]2 2, and [AuCu(C6F5)2(N[triple bond]C-CH=CH-Ph)2] 3 have been carried out. The crystal structures of complexes 1-3 consist of dinuclear Au-Cu units built from mediated metallophilic Au(I)...Cu(I) interactions. In the case of complex 2 two dinuclear units interact via an aurophilic interaction leading to a tetranuclear Cu-Au-Au-Cu arrangement. Complex 2 is brightly luminescent in solid state at room temperature and at 77 K with a lifetime in the nanoseconds range, while complexes 1 and 3 do not display luminescence under the same conditions. The presence of the aurophilic interaction in complex 2 seems to be responsible for the blue luminescence observed. DFT and time-dependent DFT calculations agree with the experimental results and support the idea that the origin of the luminescence of these complexes arise from orbitals located in the interacting metals.

The reactions of the tetraphosphine ligand DAB-G0-(PPh2)4 (DAB = 1,4-diaminobutane; G0 = Generation 0) or the octaphosphine ligand DAB-G1-(PPh2)8 (G1 = Generation 1) with the gold precursor [AuCl(tht)] (tht =tetrahydrothiophene) and the corresponding 4-substituted benzenethiolate lead to the (phosphine)gold(I) thiolate complexes [Au4(S-C6H4-X)4[(DAB-G0-(PPh2)4]] (X = F (11), MeO (12), Me (13) and NO2 (14)) and [Au8(S-C6H4-X)8[(DAB-G1-(PPh2)4]] (X = F (15), MeO (16), Me (17) and NO2 (18)). Complexes [Au4Cl4[(DAB-G0-(PPh2)4]] and [Au4(S-C6H4-OMe)4[(DAB-G0-(PPh2)4]] have been characterized by X-ray diffraction studies showing tetranuclear gold complexes in which the P-Au-X (X = Cl or S) structural units do not display aurophilic interactions. PGSE NMR studies of free ligands EN-G0-(PPh2)(4) (EN = 1,2-ethylenediamine), DAB-G0-(PPh2)(4), DAB-G1-(PPh2)8 and the (phosphine)gold(I) thiolate complexes permit the evaluation and comparison of the different molecular sizes depending on the ligand and the dendrimer generation.

The reaction between Ph2PH and C6F5CNS leads to the formation of the polyfluorinated benzothiazolephosphine ligand Ph2P(CNS)(C6F4) 1. The mechanism of the reaction involves the addition of the phosphine to the isothiocyanate and subsequent intramolecular nucleophilic aromatic substitution. This new ligand reacts with gold(I) substrates producing complexes [AuCl{Ph2P(CNS)(C6F4)}] 2 and [Au(C6F5){Ph2P(CNS)(C6F4)}] 3. Both the ligand 1 and complexes 2 and 3 display phosphorescence with emissions arising from n(P) -->pi*(heterocyclic ring) excited state for 1 and pi-->pi*(heterocyclic ring) excited state for 2 and 3. DFT and TD-DFT calculations agree with these results.

By reaction of the Lewis base NBu4[Au(3,5-C6F3Cl2)2] and AgCF3COO in the presence of NBu4CF3COO the heterometallic compound (NBu4)2[Au(3,5-C6F3Cl22Ag4(CF3COO)5] (2) is obtained. The structure displays an unprecendented square pyramidal AuAg4 arrangement built up through four AuAg closed-shell interactions and two Au-C-Ag 3c-2e- bridges.

The reaction of [AuTl(C(6)Cl(5))(2)](n) with bipy at different molar ratios, solvents or crystallisation conditions affords a series of two- and three-dimensional luminescent complexes, [AuTl(C(6)Cl(5))(2)(bipy)(0.5)](n), [AuTl(C(6)Cl(5))(2)(bipy)](n), [[Tl(bipy)][Tl(bipy)(0.5)(THF)][Au(C(6)Cl(5))(2)](2)](n), [[Tl(bipy)][Tl(bipy)(0.5)(THF)][Au(C(6)Cl(5))(2)](2)xTHF](n) and [[AuTl(C(6)Cl(5))(2)(bipy)]x0.5toluene](n)(bipy = 4,4'-bipyridine; THF = tetrahydrofuran) all of them containing polymeric chains formed via unsupported Au...Tl interactions and bridging bipyridine ligands.