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The 2,7‐fluorenone‐linked bis(6‐imidazo[1,5‐a]pyridinium) salt H2‐1(PF6)2 reacts with Ag2O in CH3CN to yield the [2]catenane [Ag4(1)4](PF6)4. The [2]catenane rearranges in DMF to yield two metallamacrocycles [Ag2(1)2](PF6)2. 2,7‐Fluorenone‐bridged bis‐(imidazolium) salts H2‐L(PF6)2 (L=2 a, 2 b) react with Ag2O in CH3CN to yield metallamacrocycles [Ag2(L)2](PF6)2 with interplanar distances between the fluorenone rings too small for [2]catenane formation. Intra‐ and intermolecular π⋅⋅⋅π interactions between the fluorenone groups were observed by X‐ray crystallography. The strongly kinked 2,7‐fluorenone bridged bis(5‐imidazo[1,5‐a]pyridinium) salt H2‐4(PF6)2 reacts with Ag2O to yield [Ag2(4)(CN)](PF6), while the tetranuclear assembly [Ag4(4)2(CO3)](PF6)2 was obtained in the presence of K2CO3. [ABSTRACT FROM AUTHOR]

A series of [2]catenanes has been prepared from di‐NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn‐[1] and the kinked biphenyl‐bridged bipyridyl ligand L2 yield the [2]catenane [2‐IL](OTf)4 by self‐assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl‐linker in L2 for a pyromellitic diimide group gave ligand L3, which yielded in combination with syn‐[1] the [2]catenane [3‐IL](OTf)4. This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L4. Di‐NHC precursor H2‐L4(PF6)2 reacts with Ag2O to give the [Ag2L42]2 [2]catenane [4‐IL](PF6)4, which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au2L42]2 gold species [5‐IL](PF6)4, which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au‐CNHC bonds. [ABSTRACT FROM AUTHOR]

A new C3‐symmetric tris‐imidazolium tribromide salt 3, featuring 1,3,5‐substituted triethynylbenzene, was used for the preparation of a trinuclear PdII pyridine‐enhanced precatalyst preparation stabilization and initiation‐type (PEPPSI) complex by triple C2 deprotonation followed by the addition of PdCl2. Trinuclear PdII complex possessing a combination of NHC and PPh3 ligands has also been synthesized. The corresponding mononuclear palladium(II) complexes have also been synthesized for the comparison purpose. All these complexes have been characterized by using NMR spectroscopy and ESI mass spectrometry. The molecular structure of the trinuclear palladium(II) complex bearing mixed carbene and pyridine donor ligands has been established by using single crystal XRD. All the palladium(II) complexes have been used as pre‐catalysts, which gave good to excellent yields in intermolecular α‐arylation of 1‐methyl‐2‐oxindole and Sonogashira coupling reaction. Catalytic studies indicate an enhanced activity of the trinuclear PdII complex in comparison to the corresponding mononuclear PdII complex for both catalytic transformations. The better performance of the trinuclear complex has also been further supported by preliminary electrochemical measurements. A negative mercury poison test was observed for both the aforementioned catalyses and therefore, it is likely that these organic transformations proceed homogeneously. [ABSTRACT FROM AUTHOR]

Dinuclear silver(I) and gold(I) complexes have been prepared from (NHC‐thiophene)‐substituted ethylene (NHC = N‐heterocyclic carbene). Both the 1,2,3,4‐tetrathienylethene (TTE)‐bridged tetrakisazolium salts (H4‐L1(PF6)4 and H4‐L2(PF6)4) and the 2,2′‐(diphenylethene‐1,1‐diyl)dithiophene (DPDT)‐bridged bisimidazolium ligand precursors H4‐L3(PF6)2 have been prepared and are treated with Ag2O to give dinuclear tetracarbene complexes [Ag2L](PF6)2 (L = L1, L2) and [Ag2(L3)2](PF6)2, respectively. The silver(I) complexes undergo a transmetalation reaction with [AuCl(THT)] (THT = tetrahydrothiophene) to furnish gold(I) NHC complexes with retention of the original structures. All complexes have been characterized by multi‐nuclear magnetic resonance (NMR) and high‐resolution electrospray ionization (HR‐ESI) mass spectrometry, and single‐crystal X‐ray diffraction analysis. The thiophene‐containing NHC complexes exhibit aggregation‐induced emission behavior in acetonitrile/water solutions and temperature‐dependent fluorescence properties. [ABSTRACT FROM AUTHOR]

The synthesis and coordination chemistry of a series of bis(benzene-o-dithiol) ligands are described that are able to form either dinuclear triple-stranded helicates or double-stranded helical complexes with titanium(IV) ions, depending on the ligand backbone. The analysis has shown that the type of bridging group between the benzene-o-dithiolato donor groups is responsible for the formation or absence of N-H...S hydrogen bonds.

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