(Isocyanide)gold(I) Thiosalicylates: Supramolecular Assembly Based on both Auriophilic and Hydrogen Bonding

Diversification of the Carbodicarbene Class by Embedding an Anionic Component in its Scaffold

Carbodicarbene (CDC) has become an emerging ligand in many fields due to its strong σ-donating ability. Collapse

Key Words

• Anionic carbodicarbene
• carbone
• dative bonding model
• geminal bimetallic complexes

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MESH Headings Collapse

Grants

• NSTC 112-2123-M-001-007 National Science Council
• AS-GC-111-M04 Academia Sinica

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Affiliation(s)

Cheng-Han Yu Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201
Ka-Chun Au-Yeung Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201 Corporate R&D Center, LCY Chemical Corporation, Kaohsiung, Taiwan (R.O.C
Ruiqin Liu School of Chemistry and Molecular Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China
Chao-Hsien Lee Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201
Dandan Jiang School of Chemistry and Molecular Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China
Bamlaku Semagne Aweke Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201 Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan (R.O.C Sustainable Chemical Science and Technology, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan (R.O.C
Chia-Hung Wu Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201 Department of Chemistry, National Taiwan University, Taipei, Taiwan (R.O.C
Yu-Jou Wang Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201 Department of Chemistry, National Taiwan University, Taipei, Taiwan (R.O.C
Ting-Hsuan Wang Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201
Kien Voon Kong Department of Chemistry, National Taiwan University, Taipei, Taiwan (R.O.C
Glenn P A Yap Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, United States
Wen-Ching Chen Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201
Gernot Frenking School of Chemistry and Molecular Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35043, Marburg, Germany
Lili Zhao School of Chemistry and Molecular Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China
Tiow-Gan Ong Institute of chemistry, Academia Sinica, Taipei, Taiwan (R.O.C., 115201 Department of Chemistry, National Taiwan University, Taipei, Taiwan (R.O.C Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan (R.O.C

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A theoretical study of M-M' polar-covalent bonding in heterobimetallic multinuclear organometallic complexes of monovalent group 11 metal centres

Complexes with closed-shell (d¹⁰-d¹⁰) interactions have been studied for their interesting luminescence properties in organic light-emitting diode (OLED) devices. The present computational study aims at understanding the chemical bonding/interactions in a series of molecules with unusually short metal-metal bond distances between monovalent coinage-metal (d¹⁰-d¹⁰) centres. The investigated molecules include pentanuclear complexes with M or M' = Cu(I), Ag(I), or Au(I) and Mes = 2,4,6-Me₃C₆H₂. In such complexes, the M-M' distances are up to 50-100 pm shorter than typical metallophilic bonds in homometallic analogues. Characterization and analysis of the chemical bond strength was performed using ab initio methods, density functional theory methods including a semi-empirical treatment of dispersion interactions (DFT-D3) and semi-empirical calculations at the extended Hückel theory (EHT) level. Population analysis suggests that hybridization occurs by mixing the (n + 1)s and (n + 1)p orbitals of M with the (nd) orbitals of M'. The orbital mixing plays a pivotal role in the polydentated polar-covalency/dative M-M' bonds that distinguish this bonding from the weaker metallophilic interactions.

Excimer and Exciplex Formation in Gold(I) Complexes Preconditioned by Aurophilic Interactions

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 (5d10 6s1 ) 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.

In-situ formation of one-dimensional coordination polymers in molecular junctions

We demonstrate the bottom-up in-situ formation of organometallic oligomer chains at the single-molecule level. The chains are formed using the mechanically controllable break junction technique operated in a liquid environment, and consist of alternating isocyano-terminated benzene monomers coordinated to gold atoms. We show that the chaining process is critically determined by the surface density of molecules. In particular, we demonstrate that by reducing the local supply of molecules within the junction, either by lowering the molecular concentration or by adding side groups, the oligomerization process can be suppressed. Our experimental results are supported by ab-initio simulations, confirming that the isocyano terminating groups display a high tendency to form molecular chains, as a result of their high affinity for gold. Our findings open the road for the controlled formation of one-dimensional, single coordination-polymer chains as promising model systems of organometallic frameworks.

Organometallic frameworks have raised considerable interest in the area of nanoelectronics, but they are usually prepared at the ensemble level resulting in limited control. Vladyka et al. control the formation of single oligomer chains, unit by unit, in a mechanically controllable break-junction setup.

Synthesis, structural characterization, biological evaluation and molecular docking studies of new platinum(ii) complexes containing isocyanides

Platinum(ii) complexes with various isocyanides are prepared and their biological activities are studied.

Dative versus electron-sharing bonding in N-oxides and phosphane oxides R3EO and relative energies of the R2EOR isomers (E = N, P; R = H, F, Cl, Me, Ph). A theoretical study

Quantum chemical calculations using ab initio methods at the CCSD(T)/def2-TZVPP level and density functional theory using BP86 and M06-2X functionals in conjunction with def2-TZVPP basis sets have been carried out on the title molecules.

New monoclinic form of {O-Ethyl N-(4-nitro-phen-yl)thio-carbamato-κS}(tri-4-tolyl-phosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis

The title phosphanegold(I) thiol-ate compound, [Au(C9H9N2O3S)(C21H21P)], is a second monoclinic polymorph (space group P21/c) that complements a previously reported Cc polymorph [Broker & Tiekink (2008 ▸). Acta Cryst. E64, m1582]. An SP donor set defines an approximately linear geometry about the gold atom in both forms. The key distinguishing feature between the present structure and the previously reported polymorph rests with the relative disposition of the thiol-ate ligand. In the title compound, the orientation is such to place the oxygen atom in close contact with the gold atom [Au⋯O = 2.915 (2) Å], in contrast to the aryl ring in the original polymorph. In the crystal, linear supra-molecular chains along the a-axis direction mediated by C-H⋯π and nitro-O⋯π inter-actions are found. These pack with no directional inter-actions between them. The analysis of the Hirshfeld surfaces for both forms of [Au(C9H9N3O3S)(C21H21P)] indicates quite distinctive inter-action profiles relating to the differences in inter-molecular contacts found in their respective crystals.

Comparison of Hydrogen and Gold Bonding in [XHX](-) , [XAuX](-) , and Isoelectronic [NgHNg](+) , [NgAuNg](+) (X=Halogen, Ng=Noble Gas)

Quantum chemical calculations at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels have been carried out for the title compounds. The electronic structures were analyzed with a variety of charge and energy partitioning methods. All molecules possess linear equilibrium structures with D∞h symmetry. The total bond dissociation energies (BDEs) of the strongly bonded halogen anions [XHX](-) and [XAuX](-) decrease from [FHF](-) to [IHI](-) and from [FAuF](-) to [IAuI](-) . The BDEs of the noble gas compounds [NgHNg](+) and [NgAuNg](+) become larger for the heavier atoms. The central hydrogen and gold atoms carry partial positive charges in the cations and even in the anions, except for [IAuI](-) , in which case the gold atom has a small negative charge of -0.03 e. The molecular electrostatic potentials reveal that the regions of the most positive or negative charges may not agree with the partial charges of the atoms, because the spatial distribution of the electronic charge needs to be considered. The bonding analysis with the QTAIM method suggests a significant covalent character for the hydrogen bonds to the noble gas atoms in [NgHNg](+) and to the halogen atoms in [XHX](-) . The covalent character of the bonding in the gold systems [NgAuNg](+) and [XAuX](-) is smaller than in the hydrogen compound. The energy decomposition analysis suggests that the lighter hydrogen systems possess dative bonds X(-) →H(+) ←X(-) or Ng→H(+) ←Ng while the heavier homologues exhibit electron sharing through two-electron, three-center bonds. Dative bonds X(-) →Au(+) ←X(-) and Ng→Au(+) ←Ng are also diagnosed for the lighter gold systems, but the heavier compounds possess electron-shared bonds.

Weaving an infinite 3-D supramolecular network via AuI⋯AuIII aurophilicity and C–H⋯Cl hydrogen bonding

The use of ligand-unsupported Au^I⋯Au^III interactions to increase the structural dimensionality to a 3-D array was demonstrated.

Crystal and molecular structures of R3PAu(3-Hmba): R=Cy and Ph; 3-H2mba=3-mercaptobenzoic acid at 173 K: Steric control of aurophilic association

The characterisation of R3PAu(3-Hmba) [R = Cy (1) and Ph (2); 3-H2mba = 3-mercaptobenzoic acid] is reported. The gold atoms exist in linear arrays defined by P- and S-donor atoms. The subtle combination of steric bulk of the phosphine ligands and steric profile of the thiolate ligand is demonstrated to exert control over the appearance of hydrogen-bonded or Au...Au-mediated dimer motifs.

Crystal and molecular structures of two triorganophosphinegold(I) 2-amino-cyclopent-1-ene-1-carbodithioates

The molecular structures of Ph3PAu · (S2CC5H6NH2-2) and (4-MeOC6H4)3PAu(S2CC5H6NH2-2) · CH2Cl2 display the expected linear S-Au-P coordination geometries. The hydrogen-bonding functionality in the 1,1-dithiolate ligands, i.e., —NH2 groups, allows for the formation of hydrogen-bonded, i.e., N—H…S, mediated chains in the respective crystal structures.

A briefing on aurophilicity

There is now compelling experimental evidence for the existence of specific intra- and intermolecular bonding between seemingly closed-shell gold(I) centers (5d10) which manifests itself in all areas of gold chemistry. This "aurophilic interaction", which had not been predicted by conventional valence theory, was found to be associated with binding energies in some cases exceeding even those of strong hydrogen bonds and therefore to be highly significant in co-determining molecular structure and dynamics. In high-level theoretical treatments the attraction is rationalized as a "super van der Waals bonding" based on particularly strong relativistic, dispersion and correlation effects (critical review, 265 references).

Supramolecular Aggregation of Mononuclear Triorganophosphinegold(I) 2-Mercaptobenzamides: Solution Structures, Thermal Decomposition, and Photoluminescence

The crystal structures of R3PAu[SC6H4C(=O)NH2-2], R = Et (1), Ph (2), and Cy (3) show linear coordination geometries for gold defined by sulfur and phosphorus atoms. Supramolecular aggregation via {...H-N-C=O}2 synthons lead to dimeric aggregates in each case. In (1) and (2), the aggregates are spherical, but steric effects exerted by cyclohexyl rings in (3) dictate a rodlike form; no Au...Au interactions were noted in the crystal structures. Solvent dependence in their NMR spectra is correlated with intra- and intermolecular hydrogen bonding. The compounds uniformly decompose under controlled conditions to give gold. The complexes excited by UV light produce strong blue-green luminescence. The configuration interaction singles (CIS) post-Hartree-Fock (HF) calculations for the compounds indicate that it is the charge transfer from the sulfur and pi-orbitals of SC6H4C(=O)NH2-2 to gold that produce the emission from gold. The assignment of the observed luminescence is presented in terms of the relaxed excited states of gold, in which the vibronic interactions for three p-orbitals of gold are taken into account.

Luminescent Phosphine Gold(I) Thiolates: Correlation between Crystal Structure and Photoluminescent Properties in [R3PAu{SC(OMe)NC6H4NO2-4}] (R = Et, Cy, Ph) and [(Ph2P-R-PPh2){AuSC(OMe)NC6H4NO2-4}2] (R = CH2, (CH2)2, (CH2)3, (CH2)4, Fc)

X-ray crystallography shows the gold atoms in [R3PAu{SC(OMe)=NC6H4NO2-4}] (R = Et, Cy, Ph; 1-3, respectively) and [(Ph2P-R-PPh2){AuSC(OMe)=NC6H4NO2-4}(2)] (R = CH2, (CH2)2, (CH2)3, (CH2)4, Fc; 4-8, respectively) are linearly coordinated by phosphorus and thiolate-sulfur; weak intramolecular Au...O interactions are featured in all structures. The smaller ethyl substituents in 1 allow for supramolecular association via Au...S and Au...Au interactions that are not found in 2 and 3, which contain larger phosphorus-bound Cy and Ph groups, respectively. Intramolecular Au...Au interactions are found in the dppm, dppe, dppp, and Fc structures but not in the dppp analogue, for which an anti conformation was found. The structures have been correlated with the results from photophysical study conducted in the solid state. Thus, photoexcitation of 1-7 with lambda > 350 in the solid state and in solution produces green and blue luminescence, respectively. The spectra in each medium are remarkably similar to each other, and so the emission energy and excitation maxima observed for 1-7 appear to be independent of the nature of the ancillary phosphines, as well as the presence or absence of Au...Au interactions, either intermolecularly or intramolecularly.

Structure Determination of Homoleptic AuI, AgI, and CuI Aryl/Alkylethynyl Coordination Polymers by X-ray Powder Diffraction

This article describes the structure determination of five homoleptic d(10) metal-aryl/alkylacetylides [RC triple bond CM] (M=Cu, R=tBu 1, nPr 2, Ph 3; R=Ph, M=Ag 4; Au 5) by using X-ray single-crystal and powder diffraction. Complex 1.C6H6 reveals an unusual Cu20 catenane cluster structure that has various types of tBuC triple bond C-->Cu coordination modes. By using this single-crystal structure as a starting model for subsequent Rietveld refinement of X-ray powder diffraction data, the structure of the powder synthesized from CuI and tBuC triple bond CH was found to have the same structure as 1. Complex 2 has an extended sheet structure consisting of discrete zig-zag Cu4 subunits connected through bridging nPrC triple bond C groups. Complex 3 forms an infinite chain structure with extended Cu-Cu ladders (Cu-Cu=2.49(4)-2.83(2) A). The silver(I) congener 4 is iso-structural to 3 (average Ag-Ag distance 3.11 A), whereas the gold(I) analogue 5 forms a Au...Au honeycomb network with PhC triple bond C pillars (Au-Au=2.98(1)-3.26(1) A). Solid-state properties including photoluminescence, nu(C triple bond C) stretching frequencies and thermal stability of these polymeric systems are discussed in the context of the determined structures.

Solvent-Dependent Coordination Polymers: Cobalt Complexes of 3,5-Dinitrobenzoic Acid and 3,5-Dinitro-4-methylbenzoic Acid with 4,4‘-Bipyrdine

The synthesis, structure elucidation, and analysis of the self-assembly of Co(II) complexes of 3,5-dinitrobenzoic acid and 3,5-dinitro-4-methylbenzoic acid with 4,4'-bipyridine have been reported. Formation of the complexes and the self-assembly in the three-dimensional structures have been found to be dependent on the solvents (such as acetone, dimethly sulfoxide, etc.) employed for the synthesis of the aggregates. 3,5-Dinitrobenzoic acid forms two coordination polymers, 1a and 1b, from methanol and a mixture of methanol and acetone solvents, respectively, with entirely different recognition patterns. Similarly, 3,5-dinitro-4-methylbenzoic acid also forms two coordination complexes, 2a and 2b, incorporating the solvent of the reaction medium into the crystal lattice. Complex 2a forms a solvated channel structure, whereas 2b gives a bilayered structure, with the layers being separated by solvent of crystallization (dimethyl sulfoxide) molecules. All the complexes have been characterized by single-crystal X-ray diffraction studies. Complexes 1b, 2a, and 2b crystallize in a monoclinic lattice, but 1a adopts a tetragonal lattice. The unit cell dimensions are, for 1a, a = 8.095(1) A, b = 8.095(1) A, c = 46.283 (6) A, alpha = 90 degrees, beta = 90 degrees, and gamma = 90 degrees (space group P4(3)2(1)2, Z = 4), for 1b, a = 22.774(2) A, b = 11.375 (1) A, c = 22.533(2) A, alpha = 90 degrees, beta = 104.15(1) degrees, and gamma = 90 degrees (space group P2(1)/c, Z = 4), for 2a, a = 17.657(6) A, b = 18.709(4) A, c = 21.044(6) A, alpha = 90 degrees, beta = 108.68(3) degrees, and gamma = 90 degrees (space group, C2/c, Z = 8), and, for 2b, a = 11.025(5) A, b = 15.139(4) A, c = 11.443(4) A, alpha = 90 degrees, beta = 97.48(3) degrees, and gamma = 90 degrees (space group P2/n, Z = 2). In all the complexes 1a, 1b, 2a, and 2b, the basic interaction between Co(II) and 4,4'-bipyridine remains the same with the formation of linear Co-N dative bonds, but the carboxylates display various modes of interaction with Co(II). The average Co-N and Co-O distances are 2.161 and 2.108 A, respectively.

A luminescent supermolecule with gold(I) quinoline-8-thiolate: crystal structure, spectroscopic and photophysical properties

The trinuclear complex [(8-QNS)(2)Au(AuPPh(3))(2)].BF(4) (8-QNS = quinoline-8-thiolate), with intramolecular gold(I)...gold(I) distances of 3.0952(4) and 3.0526(3) A, is aggregated to form a novel hexanuclear supermolecule, ([(8-QNS)2(Au(AuPPh3)2])2.(BF4)2, via a close intermolecular gold(I)...gold(I) contact of 3.1135(3) A. The beautiful hexanuclear supermolecule has an inversion center, and the six metal centers can be viewed as roughly coplanar. Six gold(I) ions are embedded in an ellipse and surrounded by 4 quinoline and 12 phenyl rings. The title compound shows interesting spectroscopic and luminescence properties dependent on the solvent polarity; i.e., it emits at ca. 440 and 636 nm in CH(2)Cl(2) and only at ca. 450 nm in CH(3)CN. The long-lived emission at ca. 636 nm (16.2 micros) in CH(2)Cl(2) is quenched by polar solvents such as CH(3)CN and CH(3)OH with quenching constants as 1.00 x 10(5) and 3.03 x 10(4) s(-1) M(-1), respectively, which is suggested to be related to the presence or absence of gold(I)...gold(I) interactions due to scrambling of the [AuPPh(3)]+ units, isolobal to H+.

Self-assembly of polymer and sheet structures in palladium(II) complexes containing carboxylic acid substituents

A series of complexes trans-[PdCl(2)L(2)] has been prepared by the reaction of [PdCl(2)(PhCN)(2)] and/or Na(2)[PdCl(4)] with L = pyridine or quinoline ligands having one or two carboxylic acid groups. These complexes can form 1-D polymers through O-H.O hydrogen bonding between the carboxylic acid groups, as demonstrated by structure determinations of [PdCl(2)(NC(5)H(4)-4-COOH)(2)], [PdCl(2)(NC(5)H(4)-3-COOH)(2)], and [PdCl(2)(2-Ph-NC(9)H(5)-4-COOH)(2)]. In some cases, solvation breaks down the O-H.O hydrogen-bonded structures, as in the structures of [PdCl(2)(NC(5)H(4)-3-COOH)(2)].2DMSO and [PdCl(2)(2-Ph-NC(9)H(5)-4-COOH)(2)].4DMF, while pyridine-2-carboxylic acid underwent deprotonation to give the chelate complex [Pd(NC(5)H(4)-2-C(O)O)(2)]. The complexes trans-[PdCl(2)L(2)], L = pyridine-3,5-dicarboxylic acid or 2,6-dimethyl pyridine-3,5-dicarboxylic acid, self-assembled to give 2-D sheet structures, with hydrogen bonding between the carboxylic acid groups mediated by solvate methanol or water molecules. In the cationic complexes [PdL'(2)L(2)](2+) (L'(2) = Ph(2)PCH(2)PPh(2), Ph(2)P(CH(2))(3)PPh(2); L = pyridine carboxylic acid; anions X(-) = CF(3)SO(3)(-)), hydrogen bonding between the carboxylic acid groups and anions or solvate acetone molecules occurred, and only in one case was a polymeric complex formed by self-assembly.

Supramolecular gold(I) thiobarbiturate chemistry: combining aurophilicity and hydrogen bonding to make polymers, sheets, and networks

The cooperative forces of aurophilic and hydrogen bonding have been used in the self-assembly of phosphine or diphosphine complexes of gold(I) with the thiolate ligands derived from 2-thiobarbituric acid, SC(4)H(4)N(2)O(2), by single or double deprotonation. The reaction of the corresponding gold(I) trifluoroacetate complex with SC(4)H(4)N(2)O(2) gave the complexes [Au(SC(4)H(3)N(2)O(2))(PPh(3))], 1, [(AuSC(4)H(3)N(2)O(2))(2)(micro-LL)], with LL = Ph(2)PCH(2)PPh(2), 2a, Ph(2)P(CH(2))(3)PPh(2), 2b, or Ph(2)PCH=CHPPh(2), 2c, or the cyclic complex [Au(2)(micro-SC(4)H(2)N(2)O(2))(micro-Ph(2)PCH(2)CH(2)PPh(2))], 3. In the case with LL = Ph(2)P(CH(2))(6)PPh(2), the reaction led to loss of the diphosphine ligand to give [Au(6)(SC(4)H(3)N(2)O(2))(6)], 4, a hexagold(I) cluster complex in which each gold(I) center has trigonal AuS(2)N coordination. Structure determinations show that 1 has no aurophilic bonding, 2b, 3, and 4 have intramolecular aurophilic bonding, and 2c has intermolecular aurophilic bonding that contributes to the supramolecular structure. All the complexes undergo supramolecular association through strong NH...O and/or OH...N hydrogen bonding, and complex 3 also takes part in CH...O hydrogen bonding. The supramolecular association leads to formation of interesting polymer, sheet, or network structures, and 4 has a highly porous and stable lattice structure.