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A tridentate trimethylstannyl substituted alkyne based on the tribenzotriquinacene (TBTQ) scaffold has been transformed into several gold(I)phosphane complexes by tin‐gold exchange. While the molecular structures of the gold(I) derivatives with less bulky trimethyl and dimethylphenylphosphane ligands exhibit intermolecular aurophilic interactions, the sterically demanding triphenylphosphane ligands inhibit the occurrence of Au⋅⋅⋅Au contacts. In addition, a hexanuclear gold(I) system was synthesised by terminal functionalisation of the hexaalkynyl TBTQ. Investigations of the photophysical properties of the gold(I)phosphane TBTQ compounds revealed their luminescent character at room temperature. [ABSTRACT FROM AUTHOR]

Hubert Schmidbaur has significantly influenced the field of gold chemistry. His work on preparing various aurocyclic digold compounds and studying their structures and reactivities has laid the foundation for unique applications in photophysics and homogeneous catalysis. The naming and characterization, both experimental and theoretical, of the aurophilicity phenomenon have led to numerous interdisciplinary applications. The emergence and development of dynamic gold chemistry in the excited state, exemplify this impact. Preparative methodologies, characterization techniques, and qualitative bonding theories have been tested through the rational preparation of ligated, element-centred gold clusters. The potential of this fascinating class of compounds remains largely untapped. [ABSTRACT FROM AUTHOR]

Trisilacyclohexanes and bissilylmethanes with acetylene units attached to silicon sites have been converted into tri‐ and di‐nuclear gold(I)phosphane complexes and characterized by NMR spectroscopy and X‐ray diffraction. The bissilylmethane‐based gold complexes were used as a test system to work out the synthetic routes before transferring them to the trisilacyclohexane scaffolds, because the latter are more difficult to access. The occurrence of aurophilic interactions (short Au ⋅ ⋅ ⋅ Au contacts) depends on the steric bulk of the phosphorus‐bonded alkyl and aryl groups. DFT studies show that dispersion effects play an important role in the ability to form intramolecular Au ⋅ ⋅ ⋅ Au interactions. QTAIM analyses show that a subtle change of the steric bulk of the phosphane groups alters the relative strength of the dispersion and aurophilic interactions. The combination of DFT studies and X‐ray diffraction experiments shows that the conformation of the trisilacyclohexane backbone is also phase dependent. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structures of two anionic cadmium dicyanoaurate coordination polymers, [nBu4N]6[(Cd4Cl4)2(Au(CN)2)12][CdCl4] (TCCA) and [nBu4N]2[Cd(Au(CN)2)4], and their reaction with ammonia vapour is reported. TCCA and the isostructural [nBu4N]6[(Cd4Br4)2(Au(CN)2)12][CdBr4] form 3‐D arrays with [Cd4X4]4+ (X=Cl, Br) cubane clusters linked from each octahedral Cd(II) centre by three bridging [Au(CN)2]− units. TCCA reacts with ammonia with concentrations of 1000 ppm or higher to give a product with a quantum yield of 0.88, while [nBu4N]2[Cd(Au(CN)2)4], which forms a 2‐D anionic Cd[Au(CN)2]2 sheet structure with axially pendant [Au(CN)2]− units, reacts with concentrated ammonia vapour to generate Cd(NH3)2[Au(CN)2]2; this has a similar 2‐D sheet structure but with axial NH3 units. Vibrational spectroscopy illustrated that the reaction of both Cd/[Au(CN)2]‐based materials with ammonia proceeded by breaking Cd‐NC bonds. For [nBu4N]2[Cd(Au(CN)2)4], this results in decomposition into [nBu4N][Au(CN)2] ⋅ 0.5H2O and Cd(NH3)2[Au(CN)2]2, while the reaction of ammonia with TCCA is reversible by heating the ammonia‐bound sample above 110 °C. Cd[Au(CN)2]2 can be prepared by thermal removal of NH3 units from Cd(NH3)2[Au(CN)2]2. [ABSTRACT FROM AUTHOR]

The novel bidentate PP and PN ligands o‐(Ph2P)−C6H4−C≡C−PPh2 (LPP) and o‐(Ph2P)−C6H4−4−(C5H9N−Me) (LPN), respectively, have been designed as long‐range "cis‐spanning" ligands for the stabilization of heterodinuclear complexes containing two metal atoms in close proximity. The synthesis of heterodinuclear, formal AuIPtII complexes with the ligand LPP is straightforward. In the course of a one‐pot reaction, a surprisingly high selectivity for the coordination of AuCl and Pt(CNC) (CNC=2,6‐diphenylpyridine‐o,o'‐diate) to the phenyl‐bound and the alkyne‐bound PPh2 sites of LPP is observed, respectively. Chloride abstraction from the resulting heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−C≡C−PPh2(Pt{CNC})] with Ag[SbF6] causes metal–metal bond formation and the generation of the cationic complex [LPPAuPt(CNC)][SbF6]. The high site selectivity for the coordination of the two metals to LPP was investigated by stoichiometric reactions of the ligand with one equivalent of the corresponding precursors. While analogous complexation experiments with LPN have not been successful, the synthesis of the heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−4‐(C5H9N−Me)(PtCl2{dmso})] and of [LPN(AuCl)2] confirm the ability of LPN to serve as a ditopic ligand. In this context, it is noteworthy that [LPN(AuCl)2] constitutes the first amine–AuCl complex featuring a tertiary amine. [ABSTRACT FROM AUTHOR]

Relativistic effects are important to understand the chemistry of heavier elements across the periodic table (PT). Three important relativistic effects are: contraction of s- and p-orbitals (direct relativistic effect), expansion of d- and f-orbitals (indirect relativistic effect) and spin–orbit (SO) coupling to split the p-, d- and f-orbitals. Each of these effects is approximately proportional to Z 2 (Z = atomic number) for the valence shell electrons in many electron atoms and consequently, these relativistic effects dominantly control the properties of the heavier elements (mainly the 6th and 7th period elements). These aspects are not given the proper importance in most of the inorganic chemistry text books and in chemistry education at the university level.

Constructing chiral supramolecular assembly and exploring the underlying mechanism are of great significance in promoting the development of circularly polarized luminescence (CPL)‐active materials. Herein, we report a solvation‐mediated self‐assembly from single‐crystals to helical nanofibers based on the first protic acyclic (methoxy)(amino)carbenes (pAMACs) AuI‐enantiomers driven by a synergetic aurophilic interactions and H‐bonds. Their aggregation‐dependent thermally activated delayed fluorescence properties with high quantum yields (ΦFL) up to 95 % were proved to be attributed to packing modes of Au⋅⋅⋅Au dimers with π‐stacking or one‐dimensional extended Au⋅⋅⋅Au chains. Via drop‐casting method, supramolecular P‐ or M‐helices were prepared. Detailed studies on the helices demonstrate that formations of extended helical Au⋅⋅⋅Au molecular chains amplify supramolecular chirality, leading to strong CPL with high dissymmetry factor (|glum|=0.030, ΦFL=67 %) and high CPL brightness (BCPL) of 4.87×10−3. Our findings bring new insights into the fabrication of helical structures to improve CPL performance by modifying aurophilic interactions. [ABSTRACT FROM AUTHOR]

Aggregating gold(I) complexes in solution through short aurophilic contacts promotes new photoluminescent deactivation pathways (aggregation-induced emission, AIE). The time dependence of spontaneous AIE is seldom studied. We examine the behavior of complex [Au(N9-hypoxanthinate)(PTA)] (1) in an aqueous solution with the aid of variable-temperature NMR, time-resolved UV–Vis and photoluminescence spectroscopy, and PGSE NMR. The studies suggest that partial ligand scrambling in favor of the ionic [Au(PTA)2][Au(N9-hypoxanthinate)2] pair followed by anion oligomerization takes place. The results are rationalized with the aid of computational calculations at the TD-DFT level of theory and IRI analysis of the electron density. [ABSTRACT FROM AUTHOR]

1,2‐Dichloro‐3,3,4,4,5,5‐hexafluorocyclopentene (F6cypCl2) was functionalized with diphenyl‐ and dimesitylphosphanyl groups by a salt‐elimination reaction of the respective chlorophosphane (PPh2Cl, PMes2Cl) with in situ generated lithiated F6cyp(Li)Cl. F6cyp(PR2)Cl (R=Ph, Mes) was functionalised again to obtain the corresponding trimethylstannyl substituted compounds F6cyp(PR2)(SnMe3) (R=Ph, Mes). These tin‐precursors were used in tin‐gold exchange reactions to synthesize the dinuclear gold(I) dimers [F6cyp(PR2)Au]2 (R=Ph, Mes). For the mesityl substituted compound, the phosphanegold chloride adduct F6cyp(PMes2AuCl)(SnMe3), the intermediate of the tin‐gold exchange reaction, could also be isolated. All compounds were characterized by multinuclear NMR spectroscopy and X‐ray diffraction experiments. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, X‐ray structures and luminescence of a series of lanthanide coordination polymers containing anionic gold(I) iso‐maleonitriledithiolate units ([Au2(i‐mnt)2]2−; {Au2[S2C=C(CN)2]2}2−) are described. Crystals of (nBu4N)Ln(DMF)8[Au2(i‐mnt)2]2 (Ln=Gd, Tb, Eu) contain 1‐D aurophilic chains of [Au2(i‐mnt)2]2− units and DMF‐saturated Ln(III) cations. The Ln=Gd and Tb systems are emissive, with λmax=596 and 625 nm respectively, attributable to the aurophilic chains. The luminescence intensities and emission energies qualitatively correlate to the local concentration of DMF vapour, where emission‐quenched (nBu4N)Ln(DMF)5[Au2(i‐mnt)2]2 is formed upon sample removal from a DMF atmosphere for 24 hours; the emissive species was regenerated by exposure to fresh DMF vapour. A similar turn‐on luminescence effect was also observed when a quenched sample of (nBu4N)Tb(DMF)5[Au2(i‐mnt)2]2 powder was exposed to pyridine, resulting in emission with λmax=625 nm. Structure‐property correlations show that the emission maximum is influenced not only by the intermolecular Au−Au distances but also by a combination of the Au−Au−Au angles and other geometric factors in the [Au2(i‐mnt)2] units. [ABSTRACT FROM AUTHOR]

New dinuclear Au(I), Au(II) and Au(III) complexes containing (CF2)n bridging chains were obtained. Metallomacrocycles [Au2{μ‐(CF2)4}{μ‐diphosphine}] show an uncommon figure‐eight structure, the helicity inversion barrier of which is influenced by aurophilic interactions and steric constraints imposed by the diphosphine. Halogenation of LAu(CF2)4AuL (L=PPh3, PMe3, (dppf)1/2, (binap)1/2) gave [Au(II)]2 species, some of which display unprecedented folded structures with Au−Au bonds. Aurophilic interactions facilitate this oxidation process by preorganizing the starting [Au(I)]2 complexes and lowering its redox potential. The obtained [Au(II)]2 complexes undergo thermal or photochemical elimination of R3PAuX to give Au(III) perfluorinated auracycles. Evidence of a radical mechanism for these decomposition reactions was obtained. [ABSTRACT FROM AUTHOR]

AuI complexes combining hard oxygen and soft (diphenylphosphanyl)ferrocene (L) ligands in their molecules were synthesized, viz. the gold hydroxides [Au(OH)(L‐κP)] (5) and [{Au(L‐κP)}2(μ‐OH)][BF4] (4), and the oxonium cluster [{Au(L‐κP)}3(μ3‐O)][BF4] (1). In‐situ auration of 1 produced [{Au(L‐κP)}4(μ4‐O)][BF4]2 (2), which spontaneously converted into a dimeric tetragold complex featuring bridging phosphanylferrocenyl groups geminally diaurated in position 2 of the ferrocene scaffold. The same complex and its isomer incorporating ferrocene‐1,1′‐diyl bridges resulted similarly from 4. Upon crystallization, compound 5 underwent a redox reaction, producing a structurally unique, crown‐like, mixed‐valent Au0/AuI cluster, [Au7(L‐κP)6]OH. Compounds 1 and 5 were used to prepare the analogous, N‐bridged complexes, [{Au(L‐κP)}3(μ3‐NFc)][BF4] (Fc=ferrocenyl) and [{Au(L‐κP)}4(μ4‐N)][BF4]. The compounds were structurally characterized and further studied by DFT calculations. [ABSTRACT FROM AUTHOR]

Recently, we have developed synthetic methods for preparing diarsenic ligands. Herein, dinuclear gold(I) chloride complexes with various kinds of diarsenic ligands [Au2Cl2(diars)] were synthesized (diars = dpae, dpap, dpab, cis‐dpav, trans‐dpav, dpapz, and dpaq). X‐ray crystallography revealed that they can form intra‐ or intermolecular aurophilic interactions depending on the ligand structure except for dpab. Crystal polymorphs of Au2Cl2(dpae) and Au2Cl2(dpap) were observed because of the flexible alkylene linkers of the diarsine ligand. The emission behaviors of the complexes were drastically changed by the ligands, which should affect the energy barrier for internal conversion from the intraligand excitation state to the halide‐to‐ligand charge transfer one. Some of the complexes accordingly showed luminescent mechanochromism and/or thermochromism. [ABSTRACT FROM AUTHOR]

New investigations combining single crystal‐ and synchrotron‐based powder X‐ray diffraction data revealed that Ba[Au2SnS4] crystallizes in the orthorhombic crystal system in space group C2221 instead of P21212 as reported earlier. While the principle crystal structure is not altered, there are significant differences of the interatomic distances Au‐S and Sn‐S. A salient property of this crystal structure is the partial framework composed of AuS2 dumbbells and SnS4 tetrahedra to form chains [(Au2SnS4)2–]∞ propagating in the [100] direction. Within the chains a short Au···Au separation of 2.9538(13) Å is observed, while the interchain Au···Au separation is longer at 3.383 Å. The Ba2+ cation is eightfold coordinated by S2– anions in a distorted bicapped trigonal prismatic environment BaS8. These polyhedra share all S2– anions thus generating a three‐dimensional network. This connection Scheme generates voids along [100] hosting [(Au2SnS4)2–]∞ chains. In addition, the compound has been shown to be luminescent at the blue‐green spectral range with emission maximum at approximately 21000 cm–1. [ABSTRACT FROM AUTHOR]

The first binuclear AuI compounds containing bridging (CF2)n chains (n=4, 6, 8) and AuIII metallaperfluorocyclopentanes have been obtained by photoinitiated reactions of LAuMe (L=PPh3, PMe3, PCy3, or IPr) with α,ω‐diiodoperfluorocarbons. Complexes LAu(CF2)4AuL present an unusual looped structure stabilized by an aurophilic interaction for L=PMe3, PPh3, and PCy3. The study of their dynamic behaviour has provided new insights about the strength of aurophilic interactions in solution, allowing quantification of the energy of a single Au⋅⋅⋅Au interaction. [ABSTRACT FROM AUTHOR]

Excimers and exciplexes are defined as assemblies of atoms or molecules A/A′ where interatomic/intermolecular bonding appears only in excited states such as [A2]* (for excimers) and [AA′]* (for exciplexes). Their formation has become widely known because of their role in gas‐phase laser technologies, but their significance in general chemistry terms has been given little attention. Recent investigations in gold chemistry have opened up a new field of excimer and exciplex chemistry that relies largely on the preorganization of gold(I) compounds (electronic configuration AuI(5d10)) through aurophilic contacts. In the corresponding excimers, a new type of Au⋅⋅⋅Au bonding arises, with bond energies and lengths approaching those of ground‐state Au−Au bonds between metal atoms in the Au0(5d106s1) and AuII(5d9) configurations. Excimer formation gives rise to a broad range of photophysical effects, for which some of the relaxation dynamics have recently been clarified. Excimers have also been shown to play an important role in photoredox binuclear gold catalysis. [ABSTRACT FROM AUTHOR]

Materials exhibiting excitation wavelength‐dependent photoluminescence (Ex‐De PL) in the visible region have potential applications in bioimaging, optoelectronics and anti‐counterfeiting. Two multifunctional, chiral [Au(NHC)2][Au(CN)2] (NHC=(4R,5R)/(4S,5S)‐1,3‐dimethyl‐4,5‐diphenyl‐4,5‐dihydro‐imidazolin‐2‐ylidene) complex double salts display Ex‐De circularly polarized luminescence (CPL) in doped polymer films and in ground powder. Emission maxima can be dynamically tuned from 440 to 530 nm by changing the excitation wavelength. The continuously tunable photoluminescence is proposed to originate from multiple emissive excited states as a result of the existence of varied AuI⋅⋅⋅AuI distances in ground state. The steric properties of the NHC ligand are crucial to the tuning of AuI⋅⋅⋅AuI distances. An anti‐counterfeiting application using these two salts is demonstrated. [ABSTRACT FROM AUTHOR]

Metallophilicity is an essential concept that builds upon the attraction between closed shell metal ions. We report on the [M2(bisNHC)2]2+ (M=AuI, AgI; NHC=N‐heterocyclic carbene) systems, which display almost identical features in the solid state. However, in solution the Au2 cation exhibits a significantly higher degree of rigidity owed to the stronger character of the aurophilic interactions. Both Au2 and Ag2 cationic constructs are able to accommodate Ag+ ions via M–M interactions, despite their inherent Coulombic repulsion. When electrostatic repulsion between host and guest is partially diminished, M–M distances are substantially shortened. Quantum chemical calculations estimate intermetallic bond orders up to 0.2. Although at the limit of (or beyond) the van der Waals radii, metallophilic interactions are responsible for their behavior in solution. [ABSTRACT FROM AUTHOR]

The synthesis of two dinuclear ionic complexes with chemical formula [Au(PR 3) 2 ][Au(C ≡ CC 5 H 4 N-4) 2 ] that contain the water soluble phosphines, PR 3 , PTA (1, 3,5-triaza-7-phosphaadamantane, 1) and DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane, 2) is herein described. The differences on their intermolecular reorganization have been analyzed and compared with the previously reported for the neutral complexes [Au(PR 3)(C ≡ CC 5 H 4 N-4)]. It has been evidenced that the reorganization of the ligands giving rise to the dinuclear ionic complexes produces a complete change in the properties giving rise to Au⋯Au intermolecular assemblies. These aurophilic contacts are the responsible for the resulting luminescence which is not displayed for the parent compounds [Au(PR 3) 2 ]Cl and [PPh 4 ][Au(C ≡ CC 5 H 4 N-4) 2 ]. Compounds 1 and 2 were made react with three different silver salts (nitrate, triflate and hexafluorophosphate) giving rise to 1:1 heterometallic assemblies with some changes both on the wavelength and emission intensity. Image 1 • The ionic complexes [Au(PR 3) 2 ][Au(C ≡ CC 5 H 4 N) 2 ] gives rise to aggregates. • X-ray structures evidences the presence of aurophilic contacts. • Absorption, emission and NMR are useful tools for the analysis of aggregation. [ABSTRACT FROM AUTHOR]

Despite being weak attractive forces, closed‐shell metallophilic interactions play important roles in the Group 11 metal complexes on their diverse structural and physical features. A plethora of experimental and computational studies has thus been dedicated to such weak attractive d10–d10 interactions, particularly aurophilic and argentophilic interactions. Although d10–d10 CuI–CuI forces had been recognized for four decades, cuprophilic interactions are less explored and they are best evidenced by single‐crystal X‐ray crystallographic analysis on CuI complexes and aggregates thereof, by which precise information about the Cu⋅⋅⋅Cu contacts, shorter than the sum of two van der Waals radii (3.92 Å) between the copper centers concerned can be obtained. Based on recently compelling experimental and spectroscopic evidence for intra‐ and intermolecular cuprophilic interactions in copper chemistry, the present Minireview summarizes recent progress in the past three decades in the synthesis and structures of multinuclear homometallic copper complexes, whereby supported and unsupported d10–d10 CuI–CuI interactions are at work.(Non)‐debatable interactions? The characterizations of cuprophilic interactions by X‐ray crystallography and Raman spectroscopy in complexes containing multinuclear copper(I) centers is presented. Furthermore, factors affecting the cuprophilic interactions (e.g., ligand scaffold, donor nature, coordination number, charge) are discussed. [ABSTRACT FROM AUTHOR]

A number of polyamide-containing multinuclear alkynylgold(I) isonitrile complexes have been designed, synthesized and characterized. The tetranuclear gold(I) complex is found to show spectroscopic responses in the presence of cadmium ions. The photophysical properties of the complex can be modulated via the suppression of photo-induced electron transfer (PET) and intramolecular Au⋯Au interactions. The binding mode of the complex has also been investigated by 1 H NMR spectroscopy. The complex is found to be highly selective towards cadmium ions as well as zinc ions. [ABSTRACT FROM AUTHOR]

Abstract: A series of gold(I) iodide complexes 1–11 have been prepared from di‐, tri‐, and tetraphosphane ligands. Crystallographic studies reveal that the di‐ (1–7) and tetrametallic (11) compounds feature linearly coordinated gold(I) ions with short aurophilic contacts. Their luminescence behavior is determined by the combined influence of the phosphane properties, metal–metal interaction, and intermolecular lattice‐defined interactions. The proposed variable contribution of 3(X+M)‐centered (X=halogen; M=metal) and 3XLCT (halogen to ligand charge transfer) electronic transitions into the lowest lying excited state, which is influenced by supramolecular packing, is presumably responsible for the alteration of room‐temperature emission color from green (λ=545 nm, for 11) to near‐IR (λ=698 nm, for 2). Dinuclear compounds 6 and 7 exhibit distinct luminescence thermochromism with a blueshift up to 5750 cm−1 upon cooling. Such dramatic change of emission energy is assigned to the presence of two coupled triplet excited states of 3ππ* and 3(X+M)C/3XLCT nature, the presence of which depends on both molecular structure and the crystal lattice arrangement. [ABSTRACT FROM AUTHOR]

This review article deals with the use of gold metalloligands as building blocks for the assembly of heterometallic complexes. Several families of gold complexes decorated with crown-ether, amide, pyridine, bipyridine, terpyridine, carboxylato, amino acid or π-alkyne binding sites have been reported. Adducts of these metalloligands with alkaline or transition-metal cations, or with transition-metal or lanthanide complexes, have been isolated and structurally characterized. The reported heterometallic species range from simple dinuclear complexes to self-assembled supramolecules, coordination polymers, or solids. New structural motifs have been found in these complexes. Most of these metalloligands and complexes are photoluminescent and some of them show switchable emissions based on the formation and rupture of metallophilic contacts. Potential applications as sensors, sensitizers, in vivo imaging agents, and anticancer drugs are envisaged. [ABSTRACT FROM AUTHOR]

A series of crown ether-based dinuclear bis(alkynyl)-bridged gold(I) isocyanide complexes has been designed, synthesized, and characterized. The intramolecular Au ···Au interactions of these complexes are used to bind potassium ions. Most of the bis(crown ether)-containing gold(I) complexes are found to obey the 1:1 binding mode towards K+. Upon addition of K+ ions, the sandwich complex of crown ether can be formed, which brings the two gold(I) centers into close proximity, resulting in the switching on of the Au ···Au interaction. The influence of the length of the bridging ligands between the two AuI centers has also been studied. Apart from the potassium ion-induced intramolecular assembly, intermolecular Au ···Au interactions of the crown ether-containing dinuclear gold(I) complexes have also been demonstrated by varying the solvent composition. [ABSTRACT FROM AUTHOR]

Multi-stimuli-responsive tetranuclear gold(I) complexes were prepared based on a tetra(alkynyl)calix[4]arene framework, with incorporation of a series of isocyanide ligands of tunable hydrophilicity. This class of complex was found to exhibit high sensitivity towards group IIIA metal ions especially In3+. Drastic electronic absorption and emission changes were observed, which could be attributed to the formation of AuI⋅⋅⋅AuI interactions during the binding event. Solvent-induced self-aggregation was also observed upon changing the solvent environment to a more polar medium, with the formation of nanoaggregates and the turning-on of the aurophilic interactions, leading to interesting luminescence and morphological changes. The aggregation process was monitored by UV/Vis absorption, emission and 1H NMR spectroscopy and dynamic light scattering (DLS) studies, and the morphological changes were studied by electron microscopy. This new class of complex has shown high sensitivity towards external stimuli and demonstrated the feasibility of employing the on-off switching of aurophilicity as an effective design strategy for the construction of functional supramolecular systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Relativistic contraction of the ns- and np- valence orbitals (direct relativistic effect), relativistic expansion of the (n − 1) d- and (n − 2) f- orbitals (indirect relativistic effect) and relativistic spin–orbit coupling to split the p- , d- and f- orbitals. • Relativistically contracted 6s- orbitial controlling the properties of the 6th period heavier elements. • Relativistic effects - the most reactive metal Cs not Fr, inertness of the noble metals and Hg, easy amalgamation with the noble metals not with the other transition metals, increased softness and stability of the higher oxidation states of the heavier d -block congeners. • Dramatically different properties of the non-relativistic (NR) elements, e.g. NR-Hg (solid and more reactive), NR-Au (white in colour, more reactive and inefficient catalyst), NR-lead acid battery useless. • Difference in the properties of lanthanides and actinides mainly due to the difference in the relativistic effect on the 4 f - and 5 f -orbitals. It is now well established that the relativistic effects strongly influence the properties of the heavier elements, specially the heavier elements of d - and f -block and also the heavier main group elements of s - and p- block. In fact, properties of the heavier elements are widely different from those of the theoretically predicted non-relativistic (NR) analogues. Several reviews on different aspects of the relativistic effects are available in very scattered forms. This review aims to make a comprehensive summary of all the known relativistic effects that influence the properties of the heavier elements like difference in electronic configurations of the heavier d -block congeners; attainment of higher oxidation states by the heavier d -block congeners; special properties of gold and mercury; liquidity of mercury at room temperature (cf. Nr-Hg is solid); chemical inertness of the noble metals and mercury; linear coordination geometry of Au(I) and Ag(I); stability of the dimeric species Au 2 , Hg 2 2+, AuPt− and AuHg+; easy formation of amalgams with the noble metals but not with the other transition metals; stability of aurides (bearing Au−); yellow colour of gold (cf. NR-Au is white); colours of Bi(V) vs Sb(V) and Pb(IV) vs Sn(IV) compounds; lanthanide and actinide contraction; difference in the properties of lanthanides (Ln) and actinides (An): magnetic and spectral properties, bonding properties of 4 f - and 5 f -orbitals, bond length, hardness–softness, ligand selectivity, etc; the most reactive metal Cs (cesium) not Fr (francium) – apparently disobeying the periodic trend; inert pair effect; closed-shell supramolecular interactions like aurophilicity (i.e. metallophilicity) and halogen bonding (XB) by the heavier halogens; catalytic activity of platinum group metals (cf. NR-analogues inefficient catalysts); spin–orbit coupling in the heavier elements and heavy atom effect on NMR shift; structural preference (2D vs 3D) of gold nanoclusters; high voltage of lead-acid and mercury batteries (cf. NR-lead-acid battery cannot start our cars); etc. [ABSTRACT FROM AUTHOR]

The syntheses of several new zinc compounds with 1,1′-bis(phosphino)ferrocene ligands and their phosphine chalcogenide derivatives are reported. The X-ray crystal structures of [Zn(dppdtbpf)Cl2] [dppdtbpf = 1-diphenylphosphino-1′-(di- tert-butylphosphino)ferrocene], [Zn(dippfO2)Cl2] [dippf = 1,1′-bis(diisopropylphosphino)ferrocene], [Zn(dtbpfO2)Cl2] [dtbpf = 1,1′-bis(di- tert-butylphosphino)ferrocene], and [Zn( 4S)Cl2] ( 4 = dppdtbpf) were determined. The oxidative electrochemistry of the zinc compounds was examined and typically produced irreversible oxidations. The reactions of [(AuCl)2(PP)] [PP = 1,1′-bis(diphenylphosphino)ferrocene (dppf), dtbpf, or dppdtbpf] with [N( p-C6H4Br)3][B(C6F5)4] result in the loss of a chlorido ligand to form [Au2(µ-Cl)(PP)][B(C6F5)4]. The structures of [(AuCl)2(dtbpf)] and [Au2(µ-Cl)(dtbpf)][B(C6F5)4] were determined, and [Au2(µ-Cl)(dtbpf)]+ displays a weak Au-Au interaction that is not present in [(AuCl)2(dtbpf)]. The oxidative electrochemistry of [Au2(µ-Cl)(PP)]+ displays two reversible waves, the first of which occurs at a potential similar to those of the corresponding [(AuCl)2(PP)] species. [ABSTRACT FROM AUTHOR]

A series of gold acetonitrile complexes [Au(NCMe)2]+[WCA]− with weakly coordinating counterions (WCAs) was synthesized by the reaction of elemental gold and nitrosyl salts [NO]+[WCA]− in acetonitrile ([WCA]− =[GaCl4]−, [B(CF3)4]−, [Al(ORF)4]−; RF =C(CF3)3). In the crystal structures, the [Au(NCMe)2]+ units appeared as monomers, dimers, or chains. A clear correlation between the aurophilicity and the coordinating ability of counterions was observed, with more strongly coordinating WCAs leading to stronger aurophilic contacts (distances, C−N stretching frequencies of [Au(NCMe)2]+ units). An attempt to prepare [Au(L)2]+ units, even with less weakly basic solvents like CH2Cl2, led to decomposition of the [Al(ORF)4]− anion and formation of [NO(CH2Cl2)2]+[F(Al(ORF)3)2]−. All nitrosyl reagents [NO]+[WCA]− were generated according to an optimized procedure and were thoroughly characterized by Raman and NMR spectroscopy. Moreover, the to date unknown species [NO]+[B(CF3)3CN]− was prepared. Its reaction with gold unexpectedly produced [Au(NCMe)2]+[Au(NCB(CF3)3)2]−, in which the cyanoborate counterion acts as an anionic ligand itself. Interestingly, the auroborate anion [Au(NCB(CF3)3)2]− behaves as a weakly coordinating counterion, which becomes evident from the crystallographic data and the vibrational spectral characteristics of the [Au(NCMe)2]+ cation in this complex. Ligand exchange in the only room temperature stable salt of this series, [Au(NCMe)2]+[Al(ORF)4]−, is facile and, for example, [Au(PPh3)(NCMe)]+[Al(ORF)4]− can be selectively generated. This reactivity opens the possibility to generate various [AuL1L2]+[Al(ORF)4]− salts through consecutive ligand-exchange reactions that offer access to a huge variety of AuI complexes for gold catalysis. [ABSTRACT FROM AUTHOR]

Crystals of mixed-valent Au complexes have been grown from solutions of cyclohexanecarbonitrile and a stoichiometric amount of gold(I) and gold(III) chloride. The purely obtained compound was characterized as bis(cyclohexanecarbonitrile)gold(I) tetrachloridoaurate(III). The crystal packing of the mixed valent Au(I/III) compound demonstrates a columnar arrangement of the gold(I) and gold(III) atoms. The new structure displays the shortest unsupported gold(I)-gold(III) interactions with the sub-van der Waals distance of 324-325 pm, which is assumed as an aurophilic bonding interaction. [ABSTRACT FROM AUTHOR]

New members of the Ln[Au(CN)2]3 ·3H2O and [ nBu4N]2[Ln(NO3)4Au(CN)2] series Ln = Ce (CeAu3 and CeAu respectively) are reported herein where their synthesis, structure and photoluminescence properties are discussed. The first is a 3-D coordination polymer with aurophilic interactions of 3.35 Å and the latter is a 1-D coordination polymer that lacks them. At 293 K both CeAu3 and CeAu display characteristic CeIII-based emission at λmax = 393 nm (5d→2FJ), however in CeAu3 AuI-based emission ( λmax = 410, 1MLCT) dominates the spectrum. At 77 K however, the dominant emission is AuI-based with characteristic emissions of λmax = 430 nm (1MLCT) and 490 nm (3MLCT). The key difference in the luminescence of these two materials can be rationalized in terms of their respective structures, through either the aurophilic network and lack thereof and/or the rigidity offered in the 3-D structure of CeAu3. [ABSTRACT FROM AUTHOR]

Reactions of the gold(I) triflimide complex [Au(NTf2)(PMe2ArDipp2 )] (1) with the gold(I) hydrocarbyl species [AuR(PMe2ArDipp2 )] (2a-2c) enable the isolation of hydrocarbyl-bridged cationic digold complexes with the general composition [Au2(μ-R)(PMe2ArDipp2 )2][NTf2], where ArDipp2 =C6H3-2,6-(C6H3-2,6-iPr2)2 and R=Me (3), CH=CH2(4), or C≡CH (5). Compound 3 is the first alkyl-bridged digold complex to be reported and features a symmetric [Au(μ- CH3)Au]+ core. Complexes 4 and 5 are the first species of their kind that contain simple, unsubstituted vinyl and acetylide units, respectively. In the series of complexes 3-5, the bridging carbon atom systematically changes its hybridization from sp3 to sp2 and sp. Concomitant with this change, and owing to variations in the nature of the bonding within the [Au(μ- R)Au]+ unit, there is a gradual decrease in aurophilicity, that is, the strength of the Au...Au bonding interaction decreases. This change is illustrated by a monotonic increase in the Au-Au distance by approximately 0.3 Å from R=CH3 (2.71 Å) to CH=CH2 (3.07 Å) and C≡CH (3.31 Å). [ABSTRACT FROM AUTHOR]

Dinuclear and mononuclear gold(I) complexes containing the xantphos ligand (xantphos = 9,9′-dimethyl-4,5-bis(diphenylphosphino)-xanthene), [Au(xantphos)](X) with X = BF ( 1), PF ( 2) and SbF ( 3 and 4) and Au(xantphos)(SCN) ( 5), were characterized by X-ray structural analysis. Two type of colourless crystals ( 3 and 4) crystallized together from the same solution of [Au(xantphos)](SbF). The [Au(xantphos)] cations have almost the same molecular structure with two xantphos ligands coordinated to two gold(I) centres with short aurophilic interaction of 2.803 ( 1), 2.825 ( 2), 2.817 ( 3) and 2.837 Å ( 4), respectively. The [Au(xantphos)] cation is in a somewhat distorted figure-eight conformation in 1- 3, whereas in 4, it has and ideal figure-eight conformation with a twofold axis passing through the Au···Au bond. The molecular packing is primarily governed by C-H···F hydrogen bonding interactions between the [Au(xantphos)] cations and fluorinated BF, PF and SbF anions. In 5, the gold(I) centre is in a trigonal-planar geometry, and it is coordinated to two phosphorous atom of the xantphos ligand and one sulphur atom of the SCN anion. Different anions cause some conformational changes and alter the molecular packing of these crystalline structures. These variations in the solid-state structures alter the luminescent properties of the dinuclear and mononuclear gold(I) xantphos complexes. Dinuclear complexes 1, 2 and 4 exhibit intense yellow luminescence, while compound 3 and mononuclear 5 produces green emission when irradiated with a 365-nm UV lamp at room temperature. [ABSTRACT FROM AUTHOR]

Intercluster compounds, [{(Au{P( p- XPh)3})2(μ-OH)}2][α-SiMo12O40(Au{P( p- XPh)3})2] · nEtOH [ X = F ( 1), Cl ( 2)] were synthesized by polyoxometalate (POM)-mediated clusterization, and were unequivocally characterized by X-ray crystallography, elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared (FT-IR), solid-state cross-polarization magic-angle-spinning (CPMAS) 31P nuclear magnetic resonance (NMR), and solution (1H, 31P{1H}) NMR spectroscopy. The 'dimer-of-dinuclear phosphanegold(I) cation', i.e., [{(Au{P( p- XPh)3})2(μ-OH)}2]2+ was formed by the self-assembly of dinuclear phosphanegold(I) cations, i.e., [(Au{P( p- XPh)3})2(μ-OH)]+, through inter-cationic aurophilic interactions as the crossed-edge arrangement (or tetrahedral Au4 structure) for 1, while as the parallel-edge arrangement (or rectangular Au4 structure) for 2. The latter arrangement was first attained only by assistance of the POM. The POM anions in 1 and 2 contained two mononuclear phosphanegold(I) cations, i.e., [Au{P( p- XPh)3}]+, linked to the OMo2 oxygen atoms of edge-sharing MoO6 octahedra. In the solution 31P{1H} NMR of 1 and 2, we observed single signals due to the rapid exchange of the phosphanegold(I) units. This shows that the OMo2 oxygen atoms of edge-sharing MoO6 octahedra in the Keggin POM act as multi-centered active binding sites for the formation of [{(Au{P( p- XPh)3})2(μ-OH)}2]2+. [ABSTRACT FROM AUTHOR]

The aurophilicity exhibited by AuI complexes depends strongly on the nature of the supporting ligands present and the length of the Au-element (Au- E) bond may be used as a measure of the donor-acceptor properties of the coordinated ligands. A binuclear iron-gold complex, [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene-2κ C2]dicarbonyl-1κ2 C-(1η5-cyclopentadienyl)gold(I)iron(II)( Au- Fe) benzene trisolvate, [AuFe(C5H5)(C27H36N2)(CO)2]·3C6H6, was prepared by reaction of K[CpFe(CO)2] (Cp is cyclopentadienyl) with (NHC)AuCl [NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. In addition to the binuclear complex, the asymmetric unit contains three benzene solvent molecules. This is the first example of a two-coordinated Au atom bonded to an Fe and a C atom of an N-heterocyclic carbene. [ABSTRACT FROM AUTHOR]

Metal-metal bonding interactions have been employed as an efficient strategy to generate a number of unique gold(I) metallo-macrocycles with fascinating functions. The self-assembly, crystal structure and emission property of novel nest-like tetramer 14, namely, {[Au4(μ-dppm)2(μ-dctp2−)](BF4)2}4 ⋅(CH3CN)2 (dppm=bis(diphenylphosphino)methane, dctp2−= N, N′-bis(dicarbodithioate)-2,11-diaza[3.3]paracyclophane) is reported. The complex has been characterized by single-crystal X-ray diffraction analysis, 1H NMR spectroscopy, 13C NMR spectroscopy, and CSI-MS spectrometry. The aggregate demonstrates the sixteen gold(I) atoms are arranged in a ring with a circumference of 50.011(68) Å generated by AuI⋅⋅⋅AuI attractions. UV/visible and luminescence spectroscopy revealed that this AuI⋅⋅⋅AuI bonded metallo-macrocycle exhibited yellow phosphorescence. [ABSTRACT FROM AUTHOR]

The protein mediated approach is a common method for the synthesis of photoluminescent gold quantum clusters (GQCs), where proteins, acting as reducing and stabilizing agents, react with gold salts through cysteine residues. For the better understanding of the phenomenon, the aqueous phase reaction of HAuCl 4 and l -cysteine has been investigated at the supramolecular level by various experimental techniques and molecular mechanics simulations. We have observed the formation of a novel photoluminescent product, ( AuCys ) n β , which shows emission in the orange region of the spectrum. Small- and wide-angle X-ray scattering (SWAXS) measurements have revealed the presence of nanosized lamellae, which have an internal multilayer superlattice structure with a characteristic periodic distance of 1.3 nm. Based on the results, the layers are built up by zigzag shaped (AuCys) n polymer chains connected through aurophilic bonds. The aurophilic network is stabilized via salt bridges and hydrogen bonds, which are also responsible for the interlayer interactions. Here, the evolution of the multilayer structure has been monitored by the combined application of photoluminescence spectroscopy and time-resolved SAXS. It has been concluded that there is a strong correlation between the emission and the scattering intensity, which suggests that the two- and three-dimensional aggregation of the building blocks to form sheets and multilayers are simultaneous processes. Furthermore, we have revealed that the formation and behavior of ( AuCys ) n β show significant differences to that of Au- l -glutathione compounds described earlier despite the similarity of l -cysteine and l -glutathione. These results evidence that l -cysteine and gold species form building blocks that can be applied expansively in supramolecular and cluster chemistry. [ABSTRACT FROM AUTHOR]

The synthesis and structural characterization of [Co 5 C(CO) 11 (AuPPh 3 ) 3 ], 1 - A and 1 - B , [Co 5 C(CO) 11 (AuPPh 3 ) 2 ] − , 2 , [Co 5 C(CO) 10 (PPh 3 ) 2 (AuPPh 3 )], 3 , [Co 5 C(CO) 12 (AuPPh 3 )], 4 , [Co 5 C(CO) 11 (PPh 3 )(AuPPh 3 )], 5 , and [Co 4 C(CO) 10 (AuPPh 3 ) 2 ], 6 , is herein reported. Compounds 1 – 6 have been obtained whilst studying the reactivity of [Co 6 C(CO) 15 ] 2− with [Au(PPh 3 )Cl] under different experimental conditions, even if better alternative syntheses have been, then, found for some of these new clusters. 1 – 6 contain the electron precise [Co 5 C(CO) 12 ] − , [Co 5 C(CO) 11 ] 3− and [Co 4 C(CO) 10 ] 2− clusters, or their PPh 3 derivatives, stabilized by [AuPPh 3 ] + fragments. Two different isomers of 1 , i.e. , 1 - A and 1 - B , have been found in the solid state due to solvation effects and weak d 10 –d 10 Au(I)⋯Au(I) aurophilic interactions. 1 - A and 4 have been previously described in the literature. [ABSTRACT FROM AUTHOR]

X-ray crystal structures of two [(diphosphine)Au2Cl2] complexes (in which diphosphine=P-Phos and xylyl-P-Phos; P-Phos=[2,2′,6,6′-Tetramethoxy-4,4′-bis(diphenylphosphino)-3,3′-bipyridine]) were determined and compared to the reported structures of similar atropisomeric gold complexes. Correlations between the Au⋅⋅⋅Au distances and torsional angles for the biaryl series of ligands (MeOBIPHEP, SEGPhos, and P-Phos; BIPHEP=2,2′-bis(diphenylphosphino)-1,1′-biphenyl, SEGPhos=[(4,4′-bi-1,3-benzodioxole)-5,5′-diyl]bis[diphenylphosphine]) can be made; these measurements appear to be very dependent upon the phosphorous substituent. Conversely, the same effect was not observed for ligands based on the binaphthyl (BINAP) series. The catalytic activity of these complexes was subsequently assessed in the enantioselective cycloisomerisation of 1,6-enynes and revealed an over-riding electronic effect: more-electron-rich phosphines promote greater enantioselectivity. The possibility of silver acting as a (co-)catalyst was ruled out in these reactions. [ABSTRACT FROM AUTHOR]

Diphenylphosphinoethyl-functionalised imidazolium salts and their silver-carbene complexes were used to synthesise a series of di- and trinuclear gold complexes through ligand exchange and transmetallation, respectively. Besides a few positively charged macrocyclic compounds with different anions (both with and without activation of the carbene function), we were able to obtain neutral polynuclear complexes by varying the gold precursor. The synthesised gold complexes show a variety of photophysical properties, including bright white photoluminescence at ambient temperature. [ABSTRACT FROM AUTHOR]