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The C–F bond activation of perfluoronaphthalene by 5-SIDipp led to the formation of dicationic salts with two fluorides (3·2HF2) or heptafluorodiborate (3·2B2F7) as counter-anions. The anion exchange reaction of 3·2B2F7 with NBu4PF6 afforded a highly luminescent 3·2PF6. The in situ addition of cobaltocene in the reaction mixture of 5-SIDipp and perfluoronaphthalene led to a distinct Co(I) species. [ABSTRACT FROM AUTHOR]

A chalcone based molecular crystal, (E)-1-(2-thienyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one, has been synthesised and analyzed with SXRD, PL-studies, 1H-NMR, 13C-NMR, DSC, TGA, DTA, SEM, IR and PXRD. The compound crystallizes in an orthorhombic crystal system with the space group Pna21 and a short axis of 4.1184(2) Å. The single crystal exhibits three molecular properties, such as fluorescence (green light emission, λ = 537.21 nm), elastic bendability under mechanical force, and photoinduced bending under light (λmax = 347 nm). The photoinduced bending is a consequence of [2 + 2] dimerization between the two parallelly-oriented molecules in the single crystal. Interestingly, after the dimerization, the photoluminescence properties and elastic bendability are extinct. The transparent emissive elastic single crystal transforms into an amorphous bent brittle solid with an arc morphology. The mechanism for this rare observation is analyzed by following the variable time light exposure PXRD pattern. During the [2 + 2] dimerization, the amorphous dimer phase randomly formed along the needle releases strain at a slow pace throughout the crystal, and the needle turns into a permanently bent solid. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and catalytic application of a new N,N′-dineopentyl-1,2-phenylenediamine-based bismuthenium cation (3). 3 has been synthesized via the treatment of chlorobismuthane LBiCl [L = 1,2-C6H4{N(CH2tBu)}2] (2) with AgSbF6, and was further used as a robust catalyst for the cyanosilylation of ketones under mild reaction conditions. Experimental studies and DFT calculations were performed to understand the mechanistic pathway. [ABSTRACT FROM AUTHOR]

The burgeoning interest in the field of molecular magnetism is to perceive the high magnetic anisotropy in different geometries of metal complexes and hence to draw a magneto-structural correlation. Despite a handful of examples to exemplify the magnetic anisotropy in various coordination geometries of mononuclear complexes, the magnetic anisotropies for two different coordination geometries are underexplored. Employing an appropriate synthetic strategy utilizing the ligand LH2 [2,2′-{(1E,1′E)-pyridine2,6-diyl-bis(methaneylylidine)}-bis(azaneylylidine)diphenol] and cobalt halide salts in a 1 : 2 stoichiometric ratio in the presence of triethylamine allowed us to report a new family of dinuclear cobalt complexes [Co II2 X2(L)(P)(Q)]·S with varying terminal halides [X = Cl, P = CH3CN, Q = H2O, S = H2O (1), X = Br, P = CH3CN, Q = H2O, S = H2O (2), X = I, P = CH3CN, and Q = CH3CN (3)]. All these complexes are characterized through single crystal X-ray crystallography, which reveals their crystallization in the monoclinic system P21/n space group with nearly identical structural features. These complexes share vital components, including Co(II) centers, a fully deprotonated ligand [L]2−, halide ions, and solvent molecules. The [L]2− ligand contains two Co(II) centers, where phenolate oxygen atoms bridge the Co(II) centers, forming a Co2O2 four-membered ring. Co1 demonstrates a distorted pentagonal-bipyramidal geometry with axial positions for solvent molecules, while Co2 displays a distorted tetrahedral geometry involving phenolate oxygen atoms and halide ions. Temperature-dependent dc magnetic susceptibility measurements were conducted on 1–3 within a range of 2 to 300 K at 1 kOe. The χmT vs. T plots exhibit similar trends, with χmT values at 300 K higher than the spin-only value, signifying a significant orbital contribution. As the temperature decreases, χmT decreases smoothly in all the complexes; however, no clear saturation at low temperatures is observed. Field-dependent magnetization measurements indicate a rapid increase below 20 kOe, with no hysteresis and a low magnetic blocking temperature. DFT and CASSCF/NEVPT2 theoretical calculations were performed to perceive the magnetic interaction and single-ion anisotropies of Co(II) ions in various ligand-field environments. [ABSTRACT FROM AUTHOR]

Molecular crystals that exhibit photomechanical responses show great promise as photoactuators and other smart materials in various fields. Herein, we synthesized two new barbituric acid derivative crystals (crystals 1 and 2), which exhibit distinct photomechanical responses towards a laser irradiation of 532 nm and UV LED photoirradiation of 365 nm, respectively. Crystal 1 demonstrated photomechanical bending upon exposure to 532 nm laser, whereas crystal 2 exhibited dramatic bursting, followed by jumping of its fragments upon UV irradiation. The photomechanical responses of both crystals are attributed to the [2 + 2] photocycloaddition reaction. However, their different kinematic responses are related to different amounts of accumulated strain energy owing to photocycloaddition and its subsequent release in the crystal lattice. The accumulation of strain energy depended on various factors such as the structural arrangement of the crystals, packing modes and overall directionality of non-covalent interactions. Furthermore, the position of the olefinic bond and peripheral substituents played a key role in determining the development of strain energy. [ABSTRACT FROM AUTHOR]

We have utilised the 4,6-di-tert-butyl resorcinol bis(diphenylphosphinite) (POCOP) ligand for exploring its coordination ability towards group 11 metal centres. The treatment of the bidentate ligand 1 with various coinage metal precursors afforded a wide range of structurally diverse complexes 2–12, depending upon the metal precursors used. This furnishes several multinuclear Cu(I) complexes with dimeric (2) and tetrameric cores (3, 4, and 5). The tetrameric stairstep complex 4 shows thermochromic behaviour, whereas the dimeric complex 2 and tetrameric complex 3 show luminescence properties at cryogenic temperatures. Interestingly, the halide substitution reaction of the dimeric complex 2 with KPPh2 produces a unique mixed phosphine-based tetrameric Cu(I) complex, 5. Treatment of the POCOP ligand with [CuBF4(CH3CN)4] in the presence of 2,2′-bipyridine afforded heteroleptic complex 6, consisting of tri- and tetra-coordinated cationic Cu(I) centres. Furthermore, we could also isolate cubane (8) and stairstep (9) complexes of Ag(I). The cationic Au(I) complex (12) was obtained from the dinuclear Au(I) complex of POCOP, 11. Complex 12 revealed the presence of a strong intramolecular aurophilic interaction with an Au⋯Au bond distance of 3.1143(9) Å. Subsequently, the photophysical properties of these complexes have been studied. All the complexes were characterised by single-crystal X-ray diffraction studies, routine NMR techniques, and mass spectroscopy. [ABSTRACT FROM AUTHOR]

Fluorine, the tiny robust atom, with its unique features has captured the attention of scientists in recent times, especially in drug discovery with its integration in small molecules, peptides, and proteins. However, studies to understand the 'fluorine effects' on the conformation of molecules that follow 'beyond the rule of 5' are in the infancy yet significant in molecular design and function. For the first time, using short hybrid peptide sequence as an appropriate model, we examined the substitution effect (size, stereoelectronic effect, and hydrogen bonding) using X‐ray diffraction, 2D‐NMR, and CD studies. The comparative study on their folding patterns with hydrogen‐substituted analogs can provide valuable insights into fluorinated substrates' design. [ABSTRACT FROM AUTHOR]

Reactions of 5‐SIDipp ⋅ BH3 (5‐SIDipp=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene) (1) with diphenyldiselenide provide access to 5‐SIDipp–boryl mono‐ (5‐SIDipp ⋅ BH2SePh) (2) and bis‐selenide (5‐SIDipp ⋅ BH(SePh)2) (3). The facile cleavage of the B−Se bond makes 2 a neutral source of selenium nucleophiles in substitutions reactions with benzyl bromides, and provide access to the corresponding selenoethers. The direct transformations of one of the C(sp2)−F bonds of C5F5N and C6F5CF3 to C−Se bonds have also been achieved by the use of 2 without employing transition‐metal catalysts. While it was previously established that C6F6 could undergo complete defluoroselenation under harsh conditions, we successfully achieved partial defluorination of C6F6 by employing 2 as a mild selenide transfer reagent. During the formation of C−Se bonds through the cleavage of C−F bonds, the potential by‐product NHC ⋅ BH2F undergoes ring expansion of the NHC, leading to the formation of the six‐membered diaazafluoroborinane (7). [ABSTRACT FROM AUTHOR]

Mechanically flexible molecular crystals have emerged as a fascinating class of materials with the ability to undergo substantial deformation without compromising their structural integrity. We report here four 3,5-di-tert-butyl salicylaldehyde based di-imine crystals. Crystals 1 and 2 were plastic while crystals 3 and 4 were brittle and elastic, respectively. By changing the length of the intervening linker molecule, structure and packing factors were influenced greatly resulting in the final outcome of mechanical properties. It is possible to fine-tune mechanical properties by changing the length of the linker moiety while keeping the peripheral shape synthons the same. These findings open up new avenues for tailoring the mechanical flexibility of molecular crystals, opening up opportunities for their application in various fields. [ABSTRACT FROM AUTHOR]

Despite the progress on cobalt and manganese catalyzed C−C and C−N bond‐forming methodologies, the associated catalyst reusability remains with some unresolved issue, which needs to be addressed. Disclosed herein, a flexible multidentate proton‐responsive ligand (L) bearing 2,6‐bis(1H‐benzo[d]imidazol‐2‐yl)pyridine (BBP), 6‐(1H‐benzo[d]imidazol‐2‐yl)picolinic acid (BPA), and benzene‐1,2‐diamine (BDA) for Co/Mn‐based mono‐ and bi‐metallic supramolecular materials for C‐/N‐alkylation of alcohols. The flexible binding sites and different hydrogen bond donor‐acceptor fragments of L brings the rigidity and self‐assembling to ordered crystalline supramolecular materials, which prevented the coordinatively saturated active sites and thus providing much higher reaction efficiency and selectivity, which is highly unlikely in the case of comparable individual components. The easy synthesis, efficient reactivity and selectivity through cooperativity, broad substrate scope, and efficient recycling via recharging of metals make the catalyst and the protocol economical and sustainable. Importantly, the design strategy based on metallo‐organic hydrogen bonded coordination assembly has the potential to contribute to the development of supramolecular materials for various advanced catalytic applications. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed, N,O‐bidentate directing group‐assisted C−H bond functionalization of benzamides with maleimides was developed for the facile access to isoindolone spirosuccinimides in good to excellent yields. This C−H bond activation and spirocyclization employing pyridine N‐oxide as directing group provided very good substrate scope and tolerated various functional groups. Furthermore, the mechanistic investigation revealed that the C−H bond activation is the rate‐determining step of this reaction. [ABSTRACT FROM AUTHOR]

The NHC·borane chemistry has been majorly restricted to imidazol-2-ylidene classes of carbenes. In our previous communication, we reported the synthesis of 6-SIDipp·BH3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene] and its electrophilic substitution reaction with iodine. Here, we have shown selective bromination of a 6-SIDipp stabilized sp3 B–H bond. Treatment of 1.2 equivalents of N-bromosuccinamide with 6-SIDipp·BH3 gives a mixture of mono- and disubstituted products 6-SIDipp·BH2Br (1) and 6-SIDipp·BHBr2 (2). However, the reactions with alkyl bromides or carbon tetrabromide resulted in 6-SIDipp·BH2Br (1) selectively. Exploration of the chemistry of 6-SIDipp with BHCl2 and 9-BBN (9-borabicyclo[3.3.1]nonane) led to mono-6-SIDipp adducts 3 and 6a. Furthermore, 6a undergoes ring expansion to afford a seven-membered product, 6b, under mild conditions. Unlike BHCl2 or 9-BBN, the B–H bond of HBpin undergoes oxidative addition upon reaction with 6-SIDipp, epitomizing the first example (7) of a B–H bond insertion at NHCs. The analogous reactivity with HBcat led to a tetrahydropyrimidinium salt with B(cat)2 as a counteranion (8). [ABSTRACT FROM AUTHOR]