Synthesis, Electronic Structure, and Reactivities of Two-Sulfur-Stabilized Carbones Exhibiting Four-Electron Donor Ability

Bis(sulfane)carbon(0) (BSC; Ph₂ S→C←SPh₂ (1)) is successfully synthesized by deprotonation of the corresponding protonated salt 1⋅HTfO. The diprotonated salt 1⋅(HTfO)₂ as the starting material can be also easily accessed by the deimination of iminosulfane(sulfane)carbon(0) (iSSC)⋅HBF₄ . Density functional theory calculations revealed the peculiar electronic structure of 1, which has two lone pairs of electrons at the central carbon atom. The largest proton affinities (PA(1): 297.5 kcal mol^-1 ; PA(2): 183.7 kcal mol^-1 ) and the highest energy levels of the HOMOs (HOMO: -4.89 eV; HOMO-1: -5.02 eV) for 1 among the two-sulfur-stabilized carbones clearly indicate the strong donor ability of carbon center stabilized by two S^II ligands. The donating ability of these lone pairs of electrons is demonstrated by the C-diaurated and C-proton-aurated complexes, which provide the first experimental evidence for two-sulfurstabilized carbones behaving as four-electron donors. Furthermore, the syntheses and application of Ag^I carbone complexes as carbone transfer agents are also reported.

[Ag115S34(SCH2C6H4t Bu)47(dpph)6]: synthesis, crystal structure and NMR investigations of a soluble silver chalcogenide nanocluster

With the aim to synthesize soluble cluster molecules, the silver salt of (4-(tert-butyl)phenyl)methanethiol [AgSCH2C6H4t Bu] was applied as a suitable precursor for the formation of a nanoscale silver sulfide cluster. In the presence of 1,6-(diphenylphosphino)hexane (dpph), the 115 nuclear silver cluster [Ag115S34(SCH2C6H4t Bu)47(dpph)6] was obtained. The molecular structure of this compound was elucidated by single crystal X-ray analysis and fully characterized by spectroscopic techniques. In contrast to most of the previously published cluster compounds with more than a hundred heavy atoms, this nanoscale inorganic molecule is soluble in organic solvents, which allowed a comprehensive investigation in solution by UV-Vis spectroscopy and one- and two-dimensional NMR spectroscopy including 31P/109Ag-HSQC and DOSY experiments. These are the first heteronuclear NMR investigations on coinage metal chalcogenides. They give some first insight into the behavior of nanoscale silver sulfide clusters in solution. Additionally, molecular weight determinations were performed by 2D analytical ultracentrifugation and HR-TEM investigations confirm the presence of size-homogeneous nanoparticles present in solution.

Planar PtPd3 Complexes Stabilized by Three Bridging Silylene Ligands

A heterobimetallic PtPd₃ complex supported by three bridging diphenylsilylene ligands, [Pt{Pd(dmpe)}₃ (μ₃ -SiPh₂ )₃ ] (1, dmpe=1,2-bis(dimethylphosphino)ethane), has been synthesized from mononuclear Pd and Pt complexes. The hexagonal core composed of Pt, Pd, and Si atoms is slightly larger than that of the tetrapalladium complex, [Pd{Pd(dmpe)}₃ (μ₃ -SiPh₂ )₃ ] (2). Reaction of PhSiH₃ with complex 1 in the presence and absence of Ph₂ SiH₂ results in the formation of a tetranuclear complex with silyl and hydride ligands at the Pt center, [PtH(SiPh₂ H){Pd(dmpe)}₃ (μ₃ -SiHPh)₃ ] (3), and an octanuclear complex, [{Pt{Pd(dmpe)}₃ (μ₃ -SiHPh)₃ }₂ (κ² -dmpe)] (5), respectively. Both M-Si (M=Pt, Pd) bond lengths and the ²⁹ Si NMR chemical shifts of 1 and 2 are located between those of mononuclear late transition-metal complexes with a silylene ligand and complexes with donor-stabilized silylene ligands. CuI and AgI adducts of 1 and 2, formulated as [M(μ-M'I){Pd(dmpe)}₃ (μ₃ -SiPh₂ )₃ ] (M=Pt, Pd; M'=Cu, Ag), undergo elimination of CuI (AgI) and regenerate the tetrametallic complexes upon heating or addition of a chelating diphosphine. Elimination of AgI from 2-AgI occurs more rapidly than elimination of CuI from 2-CuI, as determined from the results of kinetics experiments.

Design and structural characterization of the all-metal aromatic sandwich species [Bi3Au3Bi3]3−: insight from density functional theory

The [Bi₃Au₃Bi₃]³⁻ species, with hollow features, has a unique all-metal sandwich aromatic structure.

Metal-mediated generation of triazapentadienate-terminated di- and trinuclear μ2-pyrazolate NiIIspecies and control of their nuclearity

Nuclearity control of nickel(ii)–azole systems for the generation of well-defined (azolate)₂Ni^IIspecies.

Ultrafast excited-state relaxation of a binuclear Ag(i) phosphine complex in gas phase and solution

The [Ag₂(dcpm)₂]²⁺ phosphine complex displays multiexponential excited-state relaxation dynamics both in the gas phase and in solution.

Defined tetranuclear coinage metal chains

Heterodimetallic gold/copper and gold/silver complexes were synthesized, and feature an unprecedented V-shape or linear MAu₂M (M = Cu, Ag) setup in the solid state. Photoluminescence properties of the complexes strongly depend on the metal.

Synthesis, Crystal Structure, and Photoluminescent Properties of a Series of LnIII–CuI Heterometallic Coordination Polymers Based on Cu4I3 Clusters and Ln–ina Rod Units

A novel series of LnIII–CuI heterometallic coordination polymers (HCPs) {[Ln2Cu4I3(ina)7(DMA)2]n·nDMA, Ln = La (1), Ce (2), Pr (3) Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9) Ho (10), Er (11), Yb (12), Hina = isonicotinic acid, DMA = N,N-dimethylacetamide} were synthesised by a solvothermal reaction. The structures of compounds 1–12 were characterised by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Single crystal X-ray diffraction studies revealed that 1–12 are isomorphous and are 3D heterometallic coordination polymers based on inorganic Cu4I3 clusters and Ln2(ina)7(DMA) rod units. In addition, the luminescent properties of compounds 5–9 have been investigated in detail. All of them exhibited green light emission due to the synergistic effects of characteristic emissions of lanthanide ions and iodide-to-copper charge transfer.

Aggregation induced emission of gold(i) complexes in water or water mixtures

Gold(i) complexes are an expanding area of investigation due to the possibility of giving rise to supramolecular aggregates with particular morphologies that can be modulated together with their luminescent properties.

Mono- and polynuclear Ag(i) complexes of N-functionalized bis(diphenylphosphino)amine DPPA-type ligands: synthesis, solid-state structures and reactivity

DPPA-type ligands (Ph₂P)₂N(p-Z)C₆H₄ (Z = H, SMe, OMe) led to Ag(i) complexes of various nuclearities and an unexpected influence of the para-substituent Z is observed, including for CH₂Cl₂ activation.

Synthesis of cationically charged photoluminescent coinage metal nanoclusters by sputtering over a liquid polymer matrix

A generic green synthetic approach to synthesize photoluminescent metal nanoclusters of known plasmonic elements via sputtering on a biocompatible polymer matrix.

Structure-conserving spontaneous transformations between nanoparticles

Ambient, structure- and topology-preserving chemical reactions between two archetypal nanoparticles, Ag₂₅(SR)₁₈ and Au₂₅(SR)₁₈, are presented. Despite their geometric robustness and electronic stability, reactions between them in solution produce alloys, Ag_mAu_n(SR)₁₈ (m+n=25), keeping their M₂₅(SR)₁₈ composition, structure and topology intact. We demonstrate that a mixture of Ag₂₅(SR)₁₈ and Au₂₅(SR)₁₈ can be transformed to any arbitrary alloy composition, Ag_mAu_n(SR)₁₈ (n=1-24), merely by controlling the reactant compositions. We capture one of the earliest events of the process, namely the formation of the dianionic adduct, (Ag₂₅Au₂₅(SR)₃₆)^2-, by electrospray ionization mass spectrometry. Molecular docking simulations and density functional theory (DFT) calculations also suggest that metal atom exchanges occur through the formation of an adduct between the two clusters. DFT calculations further confirm that metal atom exchanges are thermodynamically feasible. Such isomorphous transformations between nanoparticles imply that microscopic pieces of matter can be transformed completely to chemically different entities, preserving their structures, at least in the nanometric regime.

Gold(I) Complexes of Ferrocenyl Polyphosphines: Aurophilic Gold Chloride Formation and Phosphine-Concerted Shuttling of a Dinuclear [ClAu···AuCl] Fragment

A smart steric control of the metallocene backbone in bis- and poly(phosphino)ferrocene ligands favors intramolecular aurophilic interactions between [AuCl] fragments in polynuclear gold(I) complexes. We synthesized and characterized by multinuclear NMR and X-ray diffraction analysis mono-, di-, and polynuclear gold complexes of constrained ferrocenyl diphosphines, which bear either bulky tert-butyl groups or more flexible siloxane substituents at the cyclopentadienyl rings. The complexes meso-1,1'-bis(diphenylphosphino)-3,3'-di-tert-butylferrocene (4-m), rac-1,1'-bis[bis(5-methyl-2-furyl)phosphino]-3,3'-di-tert-butylferrocene (5-r), and rac-1,1'-bis(diphenylphosphino)-3,3'-bis[(tri-iso-propylsilyl)oxy]ferrocene (6-r) were used to form dinuclear gold complexes. Coordination of tert-butylated ferrocenyl phosphines generated aurophilic interactions in the corresponding dinuclear gold complexes, contrary to gold(I) complexes reported with 1,1'-bis(diphenylphosphino)ferrocene. The structurally related tetraphosphine 1,1',2,2'-tetrakis(diphenylphosphino)-4,4'-di-tert-butylferrocene (11) also gave access to mononuclear, dinuclear, and the original trinuclear gold chloride aurophilic complexes in which 14e^- to 16e^- gold centers coexist. In such complexes, nonbonded ("through-space") ³¹P-³¹P' nuclear spin couplings were evidenced by high-resolution NMR. In these interactions nuclear spin information is transferred between the lone-pair electron of an uncoordinated phosphorus P and a phosphorus P' that is involved in a σ covalent bond Au-P'. The dinuclear aurophilic complex displayed a concerted shuttling of its [ClAu···AuCl] fragment between the four phosphorus donors of the tetraphosphine ligand. Thus, an aurophilic Au···Au bond, which is assumed to be a weak energy interaction, can be conserved within a dynamic shuttling process at high temperature involving an intramolecular coordination-decoordination process of digold(I) at phosphorus atoms.

N-HO and N-HCl supported 1D chains of heterobimetallic CuII/NiII-SnIV cocrystals

The Schiff base H₂L¹ [N,N'-ethylenebis(3-methoxysalicylaldimine)] or H₂L² [N,N'-ethylenebis(3-ethoxysalicylaldimine)] was reacted with MCl₂·xH₂O and SnCl₄·5H₂O to afford the supramolecular heterobimetallic systems (H₂ED)²⁺·2[ML]·[SnCl₆]^2- [M = Cu, L = L¹ (1), L = L² (2); M = Ni, L = L¹ (3), L = L² (4); ED = 1,2-ethylenediamine], whose structures were established by single crystal X-ray analyses. Each structure includes different entities, viz. a mononuclear [CuL]/[NiL] neutral complex (coformer), a hexachlorostannate dianion [SnCl₆]^2-, a 1,2-ethylenediammonium dication (H₂ED²⁺) and, only in 2 and 4, a methanol molecule. Based on the work of Grothe et al. (Cryst. Growth Des., 2016, 16, 3237-3243), compounds 1 and 3 are cocrystal salts, 2 and 4 are cocrystal salt solvates. The ionic pairs (H₂ED)²⁺·[SnCl₆]^2- in 1-4 are encapsulated by the Cu- or Ni-complexes, and stabilized by N-HO and one N-HCl bond interactions leading to infinite 1D chains. The antimicrobial studies of 1-4 against yeasts (C. albicans and S. cerevisiae) and Gram-positive (S. aureus and E. faecalis) and -negative bacteria (P. aeruginosa and E. coli) indicate that the Ni₂Sn systems (3 and 4) are more active than the analogous Cu₂Sn ones (1 and 2).

Highly Efficient Thermally Activated Delayed Fluorescence in Dinuclear Ag(I) Complexes with a Bis-Bidentate Tetraphosphane Bridging Ligand

A series of highly emissive neutral dinuclear silver complexes [Ag(PPh₃)(X)]₂(tpbz) (tpbz = 1,2,4,5-tetrakis(diphenylphosphanyl)benzene; X = Cl (1), Br (2), I (3)) was synthesized and structurally characterized. In the complexes, the silver atoms with tetradedral geometry are bridged by the tpbz ligand, and the ends of the molecules are coordinated by a halogen anion and a terminal triphenylphosphine ligand for each silver atom. These complexes exhibit intense white-blue (λ_max = 475 nm (1) and 471 nm (2)) and green (λ_max = 495 nm (3)) photoluminescence in the solid state with quantum yields of up to 98% (1) and emissive decay rates of up to 3.3 × 10⁵ s^-1 (1) at 298 K. With temperature decreasing from 298 to 77 K, a red shift of the emission maximum by 9 nm for all these complexes is observed. The temperature dependence of the luminescence for complex 1 in solid state indicates that the emission originates from two thermally equilibrated charge transfer (CT) excited states and exhibits highly efficient thermally activated delayed fluorescence (TADF) at ambient temperature. At 77 K, the decay time is 638 μs, indicating that the emission is mainly from a triplet state (T₁ state). With temperature increasing from 77 to 298 K, a significant decrease of the emissive decay time by a factor of almost 210 is observed, and at 298 K, the decay time is 3.0 μs. The remarkable decrease of the decay time indicates that thermal population of a short-lived singlet state (S₁ state) increases as the temperature increases. The charge transfer character of the excited states and TADF behavior of the complexes are interrogated by DFT and TDDFT calculations. The computational results demonstrate that the origin of TADF can be ascribed to ^1,3(ILCT + XLCT+ MLCT) states in complexes 1 and 2 and ^1,3(XLCT) states mixed with minor contributions of MLCT and ILCT in complex 3.

Functional Short-Bite Ligands: Synthesis, Coordination Chemistry, and Applications of N-Functionalized Bis(diaryl/dialkylphosphino)amine-type Ligands

The aim of this review is to highlight how the diversity generated by N-substitution in the well-known short-bite ligand bis(diphenylphosphino)amine (DPPA) allows a fine-tuning of the ligand properties and offers a considerable scope for tailoring the properties and applications of their corresponding metal complexes. The various N-substituents include nitrogen-, oxygen-, phosphorus-, sulfur-, halogen-, and silicon-based functionalities and directly N-bound metals. Multiple DPPA-type ligands linked through an organic spacer and N-functionalized DRPA-type ligands, in which the PPh2 substituents are replaced by PR2 (R = alkyl, benzyl) groups, are also discussed. Owing to the considerable diversity of N-functionalized DPPA-type ligands available, the applications of their mono- and polynuclear metal complexes are very diverse and range from homogeneous catalysis with well-defined or in situ generated (pre)catalysts to heterogeneous catalysis and materials science. In particular, sustained interest for DPPA-type ligands has been motivated, at least in part, by their ability to promote selective ethylene tri- or tetramerization in combination with chromium. Ligands and metal complexes where the N-substituent is a pure hydrocarbon group (as opposed to N-functionalization) are outside the scope of this review. However, when possible, a comparison between the catalytic performances of N-functionalized systems with those of their N-substituted analogs will be provided.

Coinage metal complexes with bridging hybrid phosphine-NHC ligands: synthesis of di- and tetra-nuclear complexes

A series of P-NHC-type hybrid ligands containing both PR2 and N-heterocyclic carbene (NHC) donors on meta-bis-substituted phenylene backbones, L(Cy), L(tBu) and L(Ph) (R = Cy, tBu, Ph, respectively), was accessed through a modular synthesis from a common precursor, and their coordination chemistry with coinage metals was explored and compared. Metallation of L(Ph)·n(HBr) (n = 1, 2) with Ag2O gave the pseudo-cubane [Ag4Br4(L(Ph))2], isostructural to [Ag4Br4(L(R))2] (R = Cy, tBu) (T. Simler, P. Braunstein and A. A. Danopoulos, Angew. Chem., Int. Ed., 2015, 54, 13691), whereas metallation of ·HBF4 (R = Ph, tBu) led to the dinuclear complexes [Ag2(L(R))2](BF4)2 which, in the solid state, feature heteroleptic Ag centres and a 'head-to-tail' (HT) arrangement of the bridging ligands. In solution, interconversion with the homoleptic 'head-to-head' (HH) isomers is facilitated by ligand fluxionality. 'Head-to-tail' [Cu2Br2(L(R))2] (R = Cy, tBu) dinuclear complexes were obtained from L(R)·HBr and [Cu5(Mes)5], Mes = 2,4,6-trimethylphenyl, which also feature bridging ligands and heteroleptic Cu centres. Although the various ligands L(R)l ed to structurally analogous complexes for R = Cy, tBu and Ph, the rates of dynamic processes occurring in solution are dependent on R, with faster rates for R = Ph. Transmetallation of both NHC and P donor groups from [Ag4Br4(L(tBu))2] to AuI by reaction with [AuCl(THT)] (THT = tetrahydrothiophene) led to L(tBu) transfer and to the dinuclear complex [Au2Cl2L(tBu)] with one L(tBu) ligand bridging the two Au centres. Except for the silver pseudo-cubanes, all other complexes do not exhibit metallophilic interactions.