Search

Herein, we have successfully achieved the stereoselective synthesis of two chiral radial [5]catenanes in a single step through the self-assembly of bidentate ligands containing l-alanine residues and binuclear half-sandwich organometallic rhodium(III)/iridium(III) clips. Remarkably, these two chiral radial [5]catenanes exhibit complex stereochemical structures as revealed by single-crystal X-ray diffraction. The eight binuclear units and eight bidentate ligands in their solid-state structures all exhibit a single planar chirality, and the interlocking between molecular macrocycles exhibits a single co-conformational mechanical helical chirality. This indicates that the introduction of the point chirality in the ligands enables the efficient stereoselective construction of mechanically interlocked molecules. Furthermore, by using ligands containing d-alanine residues, radial [5]catenanes with the opposite planar chirality and opposite co-conformational mechanical helical chirality have also been obtained.

A Cp*-Rh based D-shaped binuclear metallacycle and a template-free molecular Borromean ring (BR) were obtained in high yield using the semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (Bptmb). The topological transformation from a binuclear metallacycle and a BR to tetranuclear metallacycles was realized via the controlled oxidation of thioethers. The strategy used in this work can be regarded as a new form of stimuli-responsive post-synthesis modification (PSM).

The controllable B-H bond activation of carboranes has long been a compelling challenge. However, as the symmetry of para-carborane places the same charge on all of its ten boron atoms, controlling the regiochemistry of B-H bond activation in these molecules has remained out of reach ever since their discovery. Herein, we describe how to use steric effects to achieve a regioselective process for B-H activation of para-carborane. In this strategy, B(2,8)-H or B(2,7)-H activation patterns were achieved by taking advantage of the π-π interactions between pyridine ligands. Interestingly, by employing host-guest interactions in metallacage compounds, B(2,8)-H bond activation could be avoided and exclusive B(2,9)-H bond activation can be achieved. Steric hindrance was also found to be beneficial for regioselective B(2,8)-H bond activation in metallacage species. In this work, we demonstrate that steric effects can be a promising driving force for controllable activation of the B-H bonds of carboranes and open new opportunities in this field.

An abnormal O-coordinated zwitterionic ligand L was designed and applied to construct intricate supramolecular elements based on half-sandwich Cp*Rh units. This zwitterionic ligand has two stable conformations, C- and Z-shapes, which undergo self-adaptation when assembled with different building blocks. Two trefoil knots were obtained using dinuclear building blocks (Cp*Rh)2(1,4-DHATQ)(OTf)2 and (Cp*Rh)2(DHNAD)(OTf)2, in which the ligand L was observed to adopt its C-shaped conformation. In addition, two novel one-dimensional chains were constructed using the building blocks (Cp*Rh)2(1,5-DHATQ)(OTf)2 and (Cp*Rh)2(DHNTQ)(OTf)2. Only the Z-shaped conformation of ligand L was observed in these two 1D chains.

Two molecular metalla-knots containing over 500 non-hydrogen atoms (especially 16 RhIII ions) and one molecular Borromean ring were obtained in high yields facilitated by multiple intermolecular interactions between their components. The syntheses rely on the strategic selection of the nonlinear dipyridyl ligand 2,7-di(pyridin-4-yl)-9H-fluorene (L1) as precursor, and the structures of the assemblies were confirmed by detailed X-ray crystallographic analysis. Subsequently, replacing L1 with the bulkier ligand 4,4'-(9,9-dimethyl-9H-fluorene-2,7-diyl)dipyridine (L2) led to the formation of three tetranuclear metallocycles in high yields on account of the weakened π-π stacking interactions between the naphthacene/anthracene and fluorene moieties, which in turn confirmed the significance of stacking interactions in the construction of the molecular 818 metalla-knots and the molecular Borromean ring.

Molecular figure-eight knot (notation: 41) is extremely rare and presents great synthetic challenge due to its essentially complicated entanglement. To solve this synthetic problem, a quadruple sta...

Despite extensive research and several stunning breakthroughs in the synthesis of interlocked molecular species, [3]catenanes, Borromean rings and ring-in-ring complexes are exceedingly rare and their targeted synthesis remains a formidable challenge. Herein, a series of Cp*Rh-based homogeneous and heterogeneous interlocked structures have been prepared by coordination-driven self-assembly, not only including metalla[2]catenanes and molecular Borromean rings, but also linear metalla[3]catenanes and ring-in-ring complexes. The interlocked structures are all based on bithiophenyl groups. The bithiophenyl groups effectively enhance the strength of the inter-ring interactions and play a crucial role in the formation of these interlocked structures. By taking advantage of the strong interaction between π-donor (D) and π-acceptor (A) groups, the electron-deficient methylviologen cation was introduced into a cationic metallarectangle based on bithiophenyl groups. Taking inspiration from these results, a cationic metallarectangle based on A units was threaded into a metallarectangle based on D units, leading to a heterogeneous D–A ring-in-ring structure., A series of Cp*Rh-based homogeneous and heterogeneous interlocked structures have been prepared by coordination-driven self-assembly, not only including metalla[2]catenanes and molecular Borromean rings, but also linear metalla[3]catenanes and ring-in-ring complex.

Herein, we describe how to utilize dihydrogen bond interactions to achieve alkane recognition and hexane isomer separation. A series of metallacycles based on carborane backbones are presented herein, revealing interdependent B-Hδ-···Hδ+-C proton-hydride interactions. The metallacycles take advantage of these dihydrogen bond interactions for the separation of hexane isomers. We show that the metallacycle 3a, bearing 1,4-di(4-pyridyl)benzene (DPB), can produce n-hexane with a purity of >99% in a single adsorption-desorption cycle from an equimolar mixture of all five isomers of hexane. The isomers 2-methylpentane and 3-methylpentane can be selectively absorbed by metallacycle 4a, which bears 1,2-di(4-pyridyl)ethylene (DPE). The size of the metallacycle, C-H···π interactions, and particularly B-Hδ-···Hδ+-C interactions are the main forces governing the extent of hexane recognition. This work provides a promising principle for the design of supramolecular coordination complexes (SCCs) for the separation of alkanes.

Separation of light hydrocarbons (C

We report a design strategy for integrative assembly of heteromeric [2]catenanes. The design focuses on the shape and functional group match of two different metalla-rectangles. A series of dipyridyl ligands with different lengths, widths and functional groups were designed and used for assembly experiments. Six heteromeric [2]catenanes were obtained both by direct mixture of two pre-assembled metalla-rectangles and one-pot three-component self-assembly. Multiple analytic methods were employed to characterize the catenanes, including single crystal X-ray diffraction analysis, NMR spectroscopy, mass spectroscopy and elemental analysis.

Although a large number of novel supramolecular topologies featuring half-sandwich [Cp*Rh] units have been reported, investigations into the properties of these architectures are astoundingly rare. In addition, the bidentate ligands employed to prepare these species have remained relatively homogeneous (i.e., symmetrical bis(pyri-4-dyl) ligands). To address these paucities in the field, the novel unsymmetrical ligand L2 and the rarely reported pyri-3-dyl ligand L3, all bearing aromatic phenazine groups (an N-heterocyclic analog of anthracene), were synthesized in addition to the common symmetrical pyri-4-dyl L1. [3]Catenane, [2]catenane, and Borromean rings assemblies were constructed successfully by the self-assembly of L1 with different building blocks. Afterward, ligand L2 was applied to prepare two novel molecular-tweezer-like compounds. Lastly, a twisted [2]catenane (relative to the [2]catenane constructed using L1) and a sandwiched metallarectangle were obtained using L3. π-π stacking interactions were observed to play a significant role in stabilizing these topologies, which also promoted nonradiative migration and triggered photothermal conversion in both the solution and the solid state. In the solution state, a clear rule of thumb was derived whereby the NIR photothermal conversion efficiency increased as the π-π stacking increased, and a very high photothermal conversion efficiency (35.5-62.4%) was observed. In addition, this family of half-sandwich-based assemblies also exhibited good photothermal conversion properties in the crystalline and noncrystal powder states. This research provides a novel method to synthesize excellent NIR photothermal conversion materials featuring half-sandwich [Cp*Rh] units and points to potential applications in the near future.

The formation of two types of heterobimetallic molecular knots, double trefoil and trefoil knots, induced by s-block metal ions, is presented. Coordination of K+, Ca2+, Sr2+ or Ba2+ ions with amide groups plays a crucial role in the formation of these trefoil knots. Remarkably, the reversible topological transformation between a figure-eight knot and double trefoil or trefoil knots can be induced by coordination of s-block metal ions to amide groups. X-ray crystallographic data and NMR experiments support the structural assignments.

Herein, we report a hierarchical assembly strategy for constructing heterogeneous half-sandwich organometallic D–A (D = π-donor, A = π-acceptor) interlocked structures, and their application in near-infrared (NIR) photothermal conversion. Thienothiophene and diketopyrrolopyrrole groups were selected as the D and A units, leading to two homogeneous metalla[2]catenanes with D–D–D–D and A–A–A–A stacks, respectively. By the ordered secondary assembly of homogeneous metalla[2]catenanes, two unprecedented heterogeneous D–A metalla[2]catenanes comprising an unusual mixed D–A–D–D and unconventional D–A–A–A stacks were realized by the combination of multiple noncovalent interactions, as all demonstrated by a detailed X-ray crystallographic study. Benefiting from the mixed D–A stacking modes, NIR absorption of heterogeneous D–A metalla[2]catenanes is significantly enhanced in contrast to homogeneous metalla[2]catenanes. Thanks to the enhanced NIR absorption and the fluorescence quenching effect from half-sandwich organometallic fragments, heterogeneous D–A metalla[2]catenanes displayed high-performance NIR photothermal conversion properties (η = 27.3%)., Herein, we report a hierarchical assembly strategy for constructing heterogeneous half-sandwich organometallic D–A (D = π-donor, A = π-acceptor) interlocked structures, and their application in near-infrared (NIR) photothermal conversion.

The synthesis of complicated supramolecular architectures and the study of their reversible structural transformations remains a fascinating challenge in the field of supramolecular chemistry. Herein, two types of novel coordination compounds, a non-intertwined ring-in-ring assembly and an abnormal trefoil knot were constructed from a strategically selected Cp*Rh building block and a semi-rigid N,N′-bis(4-pyridylmethyl)diphthalic diimide ligand via coordination-driven self-assembly. Remarkably, the reversible transformation between the abnormal trefoil knot and the ring-in-ring assembly or the corresponding tetranuclear macrocycle could be achieved by the synergistic effects of Ag+ ion coordination and alteration of the solvent. Single-crystal X-ray crystallographic data and NMR spectroscopic experiments support the structural assignments., The chemical reactivity of Ag+ ions and solvent effects induce reversible structural transformations between an abnormal trefoil knot, a tetranuclear macrocycle and a ring-in-ring architecture.

By taking advantage of self-complementary π-π stacking and CH-π interactions, a series of discrete quadruple stacks were constructed through the self-aggregation of U-shaped dirhodium metallotweezer complexes featuring various planar polyaromatic ligands. By altering the conjugate stacking strength and bridging ligands, assemblies with a range of topologies were obtained, including a binuclear D-shaped macrocycle, tetranuclear open-ended cagelike frameworks, and duplex metallotweezer stacking structures. Furthermore, a rare stacking interaction resulting in selective C-H activation was observed during the self-assembly process of these elaborate architectures.

A novel template-free Cp*Rh-based molecular Solomon link has been established through selection of the flexible ligand L as a linker and the half-sandwich rhodium(III) dinuclear fragment B1 as a rigid capping unit. Furthermore, we demonstrate that the self-assembly of the Solomon link based on the flexible ligand is both solvent- and concentration-dependent: the Solomon link is formed in concentrated methanolic solutions, whereas formation of a dinuclear trapezoidal rectangle is favored at low concentrations or in acetonitrile or DMF solutions. Remarkably, alteration of the solvent or concentration can promote a unique and dynamic interconversion between the two molecular species, accompanying conformational change of the ligand. The synthetic outcomes are supported by single-crystal X-ray diffraction analysis.

A stepwise self-assembly protocol has been used to synthesize [2]- and [3]catenanes. Firstly, binuclear Cp*Rh/Ir-directed (Cp*=pentamethylcyclopentadienyl) pseudorotaxanes were prepared through self-assembly, driven by donor-acceptor interactions between electron-deficient naphthalenediimide (NDI) units and an electron-rich crown ether. Subsequently, the pre-organized pseudorotaxanes were applied as tectons for self-assembly of [2]- and [3]catenanes by combination with very simple linkers. The structures of the catenanes were confirmed by NMR spectroscopy, ESI mass spectrometry, single-crystal X-ray diffraction analysis, and elemental analysis.

A template-free Cp*Ir-based molecular Solomon link and an unusual trefoil knot induced by stacking interactions were realized via selection of the nonrigid dipyridyl ligand 4,4'-bis(pyridin-4-ylmethyl)-1,1'-biphenyl (BpmBp). In addition, a novel heterobimetallic tetranuclear (IrIII2 + AgI2) complex featuring argentophilic interaction was synthesized in high yield. Remarkably, the reversible topological transformation between the Solomon link and an unusual trefoil knot can be achieved by utilizing the chemical reactivity of silver(I) ions under mild conditions, as demonstrated by a detailed X-ray crystallographic study.

Herein, we present a new synthetic approach to achieve selective supramolecular transformations and construct different interlocked metallacycles featuring a π-electron-deficient thiazolo[5,4-d]thiazole-derived ligand. We demonstrate that the formation of mono-rings, interlocked rings ([2]catenanes) and Borromean rings can be controlled by adjusting the length of the binuclear half-sandwich RhIII and IrIII building blocks. Furthermore, a concentration effect or D-A stacking interaction between the pyrene guest and the thiazolo[5,4-d]thiazole-based ligand promotes a unique and reversible conversion between catenane structures and metalla-rectangles. The synthetic results are supported by single-crystal X-ray diffraction analysis.

A series of supramolecular transformation cascades are presented here, employing ligand exchange reactions, concentration-dependent Borromean ring (BR) linking and unlinking, and inverse electron-demand Diels-Alder (IEDDA) reactions. The new family of template-free, tetrazine-edged BRs are constructed by using ligand exchange reactions, and their concentration-dependent linking and unlinking reactions have been observed. Moreover, Borromean precursors have been demonstrated to further undergo supramolecular structural transformations induced by rapid and efficient IEDDA reactions to afford corresponding post-assembly modified architectures. Remarkably, subtle steric increases of the pyridazine fragments obtained by IEDDA reactions is regarded to induce controlled topological transformations in the cascade, unlinking the Borromean structures by using electron-rich dienophiles as triggering signals.

Two Cp*-RhIII based trefoil knots were obtained in high yield under ambient conditions via the coordination-driven self-assembly of semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (L1 ), ligand chloranilic acid (H2 -CA) and 6,11-dihydroxytetracene-5,12-dione (H2 -TtDo) with Cp*RhIII metal corner units, respectively. Furthermore, using the bulkier 4,4'-{[(2,5-dimethyl-1,4-phenylene)bis(methylene)]bis(sulfanediyl)}dipyridine (L2 ) in the place of ligand L1 in the construction process resulted in the formation of a teranuclear metallacycle and a template-free Borromean ring in high yields thanks to significantly altered intermolecular forces between the constituent ligands induced by the sterically-hindering methyl groups of L2 , as demonstrated via a detailed X-ray crystallographic analysis and NMR spectroscopy.

The coordination-driven self-assembly of organometallic half-sandwich iridium(III)- and rhodium(III)-based building blocks with asymmetric ambidentate pyridyl-carboxylate ligands is described. Despite the potential for obtaining a statistical mixture of multiple products, D

The controllable B-H bond activation of carboranes has long been a compelling challenge. However, as the symmetry of

Two molecular metalla-knots containing over 500 non-hydrogen atoms (especially 16 Rh

Expanding the family of f-element bearing molybdate iodates via hydrothermal reactions has yielded ten new rare-earth molybdate iodates with two distinct phases, Ln(MoO2)(IO3)4(OH) (LnMoIO-1, Ln = Ce and Pr) and Ln(Mo2O7)(IO3)(H2O)2 (LnMoIO-2, Ln = Gd-Yb, and Y), as well as the first thorium molybdate iodate, ThF(MO4)(IO3) (ThFMoIO). All three structures exhibit three dimensional frameworks and are exclusively built from lanthanide/actinide polyhedra bridged by molybdates and iodates. Furthermore, the coordination versatility of molybdates (octahedral, square pyramidal, and tetrahedral geometries) results in a diversity of structures. The effect of the lanthanide contraction on the compositions and structures is clearly observed, showing the increase in hydration from the early to late lanthanide analogues and the decrease in unit cell dimensions and the average Ln-O bonding distances across the same structure type. Single crystal X-ray diffraction studies reveal that LnMoIO-1 (Ln = Ce and Pr) crystalize in a noncentrosymmetric space group P21 and the second-harmonic generation (SHG) measurement shows a response of 5 × KDP for PrMoIO-1. In addition, CeMoIO-1 crystallizes as orange coloured tablets which are semiconducting in nature with a band gap of 2.41 eV.

The directing effect of coordinating ligands in the formation of uranium molecular complexes has been well established, but the role of counterions in metal-ligand interactions remains ambiguous and requires further investigation. In this work, we describe the targeted isolation, through the choice of alkali-metal ions, of a family of tetravalent uranium sulfates, showing the influence of the overall topology and, unexpectedly, the UIV nuclearity upon the inclusion of such countercations. Analyses of the structures of uranium(IV) oxo/hydroxosulfate oligomeric species isolated from consistent synthetic conditions reveal that the incorporation of Na+ and Rb+ promotes the crystallization of 0D discrete clusters with a hexanuclear [U6O4(OH)4(H2O)4]12+ core, whereas the larger Cs+ ion allows for the isolation of a 2D-layered oligomer with a less condensed trinuclear [U3(O)]10+ center. This finding expands the prevalent view that counterions play an innocent role in molecular complex synthesis, affecting only the overall packing but not the local oligomerization. Interestingly, trends in nuclearity appear to correlate with the hydration enthalpies of alkali-metal cations, such that the alkali-metal cations with larger hydration enthalpies correspond to more hydrated complexes and cluster cores. These findings afford new insights into the mechanism of nucleation of UIV, and they also open a new path for the rational design and synthesis of targeted molecular complexes.

Herein, we describe the design and synthesis of three tetranuclear complexes, [(Cp*Rh)(L1)]4(OTf)4 (1a, HL1 = 2-(pyridin-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), [(Cp*Ir)(L1)]4(OTf)4 (1b), and [(Cp*Rh)(L2)]4(OTf)4 (2, HL2 = 2-(4-(pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline). Owing to the precise design of the phenanthroline-derived ligands, these complexes exhibit perfect square-shaped structures with side lengths of 13.53, 13.57, and 17.95 A, respectively. These molecules orderly align and assemble into square-shaped, one-dimensional nanotubes. The molecular structures and arrangement of the nanotubes were evidenced by single-crystal X-ray diffraction. Solution behavior was studied by NMR spectroscopy. Fourier transform infrared spectroscopy and elemental analysis were also employed to characterize these complexes.

A series of bis-salicylaldimine ligands bearing two ON-donor functions were reacted with dichloro(p-cymene)ruthenium(II) dimer in the presence of base (NaOAc) and a series of four dimetallic Ru(II) arene complexes (Ru(p-cymene))2(bis-salicylaldimine)Cl2 (C1 C4) were prepared. These complexes were obtained in excellent isolated yields and characterized in detail by using different spectroscopic techniques. The structure of C1 was also determined in solid state by single crystal X-ray analysis. These complexes were studied for their cytotoxic effect against three different types of human cancer cells including hepatocellular carcinoma (HepG2), non-small-cell lung cancer (A549) and breast cancer (MCF-7) cells by MTT assay. These complexes showed considerable cytotoxic effect in all the above-mentioned cell lines that was comparable to the effect of cisplatin. C1 and C2 showed moderate anticancer effect while C3 and C4 showed reasonable cytotoxicity. We found the cytotoxicity was increased in series from C1 to C4 representing the effect of ligand modification from small to bulky group at the amine functionality of the salicylaldimine. We selected C3 and C4 for mechanistic anticancer study in MCF-7 cells. The acridine orange/ethidium bromide and DAPI staining assays of MCF-7 cells treated with Ru(II) complexes showed apoptosis in cancer cells. Similarly, these complexes induced p53 protein expression in MCF-7 cells. Further, increased mRNA levels of p63, p73, PUMA, BAX and NOXA genes were observed in response to the treatment with C3 and C4, while cyclinD1, MMP3 and ID1 gene expression was significantly reduced. We found reduced invasion ability in breast cancer cells treated with C3 and C4. Taken together, we demonstrated that bis-salicylaldimine based dimetallic Ru-(p-cymene) complexes exerts anticancer effects by p53 pathway, suggesting the promising chemotherapeutic potentials of these Ru(II) complexes for the treatment of cancer. This study may further pave for their in depth in vitro or in vivo anticancer investigations.

A series of benzoxazolyl and benzothiazolyl phosphine ligands 4a-4g were synthesized and characterized, which prepared from commercially available 2-aminophenol/2-aminobenzenethiol and 2-bromobenzaldehyde via cyclization and phosphination. The representative ligands 4c and 4e were determined by single-crystal X-ray diffraction. The corresponding iridium complexes could be generated in situ when [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) encountered ligands. The molecular structures of complexes 5c and 5e were crystallographically characterized. The dihedral angles of N (1)-C (1)-C (8)-C (9) showed an increasing twist compared with the corresponding ligand. The iridium (III) catalysts were screened, [Cp*IrCl2]2/4a proved to be the optimal catalyst, which exhibited efficient catalytic activity toward versatile alkylations including ketones, secondary alcohols and amines with primary alcohols. Additionally, the synthesis of quinolines from ketones with 2-aminobenzyl alcohol by intermolecular cyclization and indole from 2-(2-aminophenyl)ethanol by intramolecular cyclization were achieved under the optimized conditions.

Herein, we describe the utilization of isomeric pyridyl-substituted ligands featuring different coordination vectors to rationally design and construct a series of discrete organometallic assemblies with specific space conformations. In the case of tetranuclear macrocycles constructed from the ligand 3-bpb, different conformations of these assemblies with C2v and C2 h point symmetry were revealed by single-crystal X-ray diffraction. These complexes were further characterized by X-ray crystallography, 1H NMR, DOSY NMR, IR spectroscopy, and elemental analyses.

Although reversible photo-dimerization or oxygenation of anthracene and its derivatives is a common reaction, light-initiated reversible conversion of endoperoxide organometallic frameworks has only rarely been addressed. Herein, a series of tetranuclear organometallic macrocycles, [Cp*2Rh2(μ-C2O4-κO)]2(BP4VA)2(OTf)4 (4), [Cp*2Rh2(BiBzIm)]2(BP4VA)2(OTf)4 (5), and [Cp*2Rh2(DHBQ)]2(BP4VA)2(OTf)4 (6), were obtained in good yields from the reactions of the binuclear half-sandwich rhodium precursors [Cp*2Rh2(μ-C2O4-κO)Cl2] (1), [Cp*2Rh2(BiBzIm)Cl2] (2), and [Cp*2Rh2(DHBQ)Cl2] (3) with the 9,10-bis((E)-2-(pyrid-4-yl)vinyl)anthracene (BP4VA) ligand. The photochemical reaction of these metallarectangles was investigated by NMR and UV/vis spectroscopy. We have demonstrated that complexes 4, 5, and 6 can be reversibly and nearly quantitatively converted to the macrocyclic endoperoxides 4-O2, 5-O2, and 6-O2. Meanwhile, the structure of the endoperoxide photoproducts was unambiguously confirmed by 1H/13C NMR spectroscopy, IR spectroscopy, elemental analyses, and X-ray crystallography.

A series of hexanuclear rectangular macrocycles were designed and synthesized by utilizing multifunctional pyrazine-derived (pyrazine-2,3-diamine (H4L1)) and quinoxaline-derived ligands (2,3-dihydroxy-quinoxaline (H2L2)) featuring two monodentate sites and one pair of chelating sites. X-ray crystallography in combination with 1H NMR spectroscopy elucidated that both half-sandwich iridium diimine and dihydroxy moieties are located on either side of the rectangular macrocycles, making them centrosymmetric. Thereby, the prepared diimine-functionalised complexes were found to have unsaturated metal sites on account of their strongly bound Ir-N-C-C-N arrangement. However, all the iridium atoms in the rectangular macrocycles containing dihydroxy groups were found to adopt an 18-electron coordination configuration, indicating that the O,O'-bonded iridium centers had bound additional ligands, such as Cl-, MeOH, MeCN, etc. Notably, a rare rectangular macrocycle containing a single coordinatively unsaturated metal site was achieved when the ligands H2L12- and L22- were introduced simultaneously.

A series of bimetallic and trimetallic complexes has been prepared by N-alkylation of mononuclear half-sandwich rhodium and iridium di-NHC complexes featuring bidentate chelate ligands composed of a classical NHC and a C-azolato donor. The shape and the separation between metal centers in the obtained complexes are highly dependent on the alkylating agent used. While the polynuclear complexes were formed as diastereomeric mixtures according to NMR spectroscopy, X-ray diffraction analysis revealed their remarkable preference to crystallize as meso compounds. The reactivity of the bimetallic, olefin-bridged complexes in electrophilic addition reactions has been investigated.

Three aromatic ligands containing carboxyl- or nitrogen-substituted groups were employed in the construction of half-sandwich complexes via C-H activation-directed assembly, leading to the construction of eleven multinuclear organometallic iridium or rhodium complexes, including those of bi-, tetra-, hexa- and octanuclear, under mild conditions, with the help of N-donor linkers. These complexes were characterized by proton NMR, IR spectroscopy, elemental analysis, electrospray ionization (ESI) mass spectrometry and single-crystal X-ray diffraction analysis. In these complexes, two complexes were observed to exist as isomers, and several racemic enantiomers can be found. X-ray crystal structure determinations show that a series of supramolecular tunnel architectures are formed by stacking through hydrogen-bond interactions, and solvent or trifluoromethylsulfonate anion guests were found to be located in certain parts of the channels. This work represents the first successful construction of octanuclear half-sandwich complexes based on the cleavage of C-H bonds.

A series of Cp*Rh-based molecular Borromean rings (BRs) are prepared from naphthazarine or metallaligand. Some of as-synthesized BRs display high stability and are formed in high yields in solution. The reason is related to the length ratio of the long-arm linker and short-arm linker, where smaller aspect ratios of the metallarectangles promote improved stability and yields of the BRs in solution. Increasing the width of the metallaligand or pyridyl ligand hinders the formation of BRs and leads to unoccupied monomeric rectangles, which were further used as catalysts for the acyl transfer reaction between N-acetylimidazole and (4-(pyridin-4-yl)phenyl) methanol.

Systematic control of the molar ratio between thorium hydroxides and selenic acid and their reaction temperature under hydrothermal conditions results in four novel thorium-based selenate complexes, namely, [Th8O4(OH)8(SeO4)6(H2O)16]·(SeO4)2·13H2O (Th-1), [Th8O4(OH)8(SeO4)8(H2O)13]·7H2O (Th-2), Th(OH)2(SeO4)H2O (Th-3), and Th3(SeO4)6(H2O)6·2.5H2O (Th-4), as well as the thorium mixed selenite selenate compound Th(SeO3)(SeO4) (Th-5). Smaller [H2SeO4]/[Th(IV)] ratio or lower temperature give rise to the formation of octameric [Th8(μ3-O)4(μ2-OH)8]16+ cores in Th-1/Th-2 and infinite [Th(μ2-OH)2H2O]2+ chains in Th-3, respectively. Increasing the [H2SeO4]/[Th(IV)] ratio or elevating the temperature generates a microporous (11.3 A voids) open-framework Th-4, a monomeric thorium species without oxo/hydroxyl ligands, and a three-dimensional thorium structure Th-5. Formation of these compounds suggests that variables including acidity and temperature play a critical role in the hydrolysis and oligomerization of ThIV...

4-Amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4-abpt) as bent bridging ligand has been utilized to construct half-sandwich tetranuclear organometallic complexes, namely [Cp*4M4(C2O4)2(4-abpt)2](OTf)4 (M = Rh(1); Ir(2)) and [Cp*4M4(bibzIm)2(4-abpt)2](OTf)4 (M = Rh(3); Ir(4)). Single-crystal X-ray diffraction structural analysis combined with 1H NMR spectra reveal that complexes 1–4 show rectangular macrocycles, in which half-sandwich binuclear units are interlinked by 4-abpt ligands that have relatively flexible angle changes. For macrocycles 1–3, they all feature an anti-arrangement of 4-abpt ligands; However, 4-abpt ligands adopt a syn-arrangement in macrocycle 4.

For the first time, carborane complexes containing a B(4)–S bond were obtained directly by heating mononuclear Pd-B(4)-bound carborane complexes. A possible mechanism involved in sulfur atom migration is presented in which the leaving group, pyridine, benzyl isocyanide or PPh3, is demonstrated to be the trigger of the reaction process. In this work, efficient routes are developed through one-pot reactions to prepare B(4)-S carborane derivatives.

Different types of multinuclear half-sandwich rhodium macrocycles and cages were designed and synthesized by using two similar multifunctional hydroxamate ligands (pyrazine-2-hydroxamic acid (NaHL1 ) and 4,4'-bipyridine-2-hydroxamic acid (KHL2 )) featuring one monodentate site and two pairs of chelating sites. The RhIII -PdII heterometallic macrocycles were constructed by using the semi-open palladium(II) source [Pd(en)Cl2 ] with two free acceptor sites. However, only one kind of macrocycle was found when the shorter ligand L1 was used, while in for the larger ligand, various spectroscopic techniques demonstrated the coexistence of hexanuclear and octanuclear macrocycles in solution and the proportions of both components depended on concentration and temperature. The palladium salt Pd(NO3 )2 , as a source of "naked" Pd2+ , was introduced to assemble the cuboid-shaped cage composed of two types of metal ions and three types of organic ligands. In addition, two silver(I)-containing mixed-metal complexes bridged by pyrazine were obtained, in which two forms of decanuclear complex with C2v and C2h point symmetry cocrystallized-one is a polymeric structure and the other is a discrete cage. However, the third form, with D2 point symmetry, was found in the larger cage.