Halogen-Dependent Diversity and Weak Interactions in the Heterometallic Ni/Cd Complex Solids: Structural and Theoretical Investigation.

Three novel heterometallic Ni/Cd coordination compounds [Ni(en)][CdCl]∙3dmso (), [Ni(en)(dmf)][CdBr] (), and [Ni(en)][CdI](I) () have been synthesized through the self-assembly process in a one-pot reaction of cadmium oxide, nickel salt (or nickel powder), NHX (X = Cl, Br, I), and ethylenediamine in non-aqueous solvents dmso (for ) or dmf (for and ). Formation of the one- () or three-dimensional ( and ) hydrogen-bonded frameworks has been observed depending on the nature of the [CdX] counter-anion, as well as on the nature of the solvent. The electronic structures of [Ni(en)] and [Ni(en)(dmf)] cations were studied at the DFT and CASSCF levels, including the ab initio ligand field theory (AILFT) calculations.

Inert Transition Metal Ion Complexes in Organic Synthesis: Protection and Activation.

Single-crystal X-ray diffraction studies for a variety of metal ion complexes of functionalised sarcophagines (sarcophagine=sar=3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane) have further confirmed not only that the form of the metal ion/sar unit is unique for each metal, albeit with a sensitivity of the conformation to the associated counter anions, but also that for any given metal and ligand substituent, the dimensions (bond lengths and angles) of the complex and the substituent at the secondary nitrogen centres do not differ significantly from those of the isolated components.

Synthesis, crystal structure and Hirshfeld surface analysis of the hybrid salt bis-(2-methyl-imidazo[1,5-]pyridin-2-ium) tetra-chlorido-manganate(II).

The 0-D hybrid salt bis-(2-methyl-imidazo[1,5-]pyridin-2-ium) tetra-chlorido-manganate(II), (CHN)[MnCl] or [][MnCl], consists of discrete cations and tetra-chlorido-manganate(II) anions. The fused heterocyclic rings in the two crystallographically non-equivalent monovalent organic cations are almost coplanar; the bond lengths are as expected. The tetra-hedral MnCl dianion is slightly distorted with the Mn-Cl bond lengths varying from 2.

2,7- and 4,9-Dialkynyldihydropyrene Molecular Switches: Syntheses, Properties, and Charge Transport in Single-Molecule Junctions.

This paper describes the syntheses of several functionalized dihydropyrene (DHP) molecular switches with different substitution patterns. Regioselective nucleophilic alkylation of a 5-substituted dimethyl isophthalate allowed the development of a workable synthetic protocol for the preparation of 2,7-alkyne-functionalized DHPs. Synthesis of DHPs with surface-anchoring groups in the 2,7- and 4,9-positions is described.

Toward the Total Synthesis of Alpkinidine: Michael Addition to Isoquinolinetrione CE Ring-System Synthons.

Strategies toward the total synthesis of the marine pyrroloacridine alkaloid alpkinidine have been explored, focusing on linking quinonoid CE ring-system synthons with the A ring, followed by condensation to form the B and D rings. The key Michael addition of the ester enolate derived from ethyl -nitrophenylacetate to 2-methylisoquinoline-1,5,8(2)-trione proceeded with the wrong regiochemistry. This issue was addressed by incorporating the D-ring nitrogen at an earlier stage, affording advanced intermediates possessing the complete carbon skeleton of alpkinidine.

Toward the Total Synthesis of Alpkinidine: Synthesis of Haloquinone CE Ring System Synthons and Attempted Nucleophilic Bisannulation.

Model chemistry involving the bisannulation of 2,3-dichloro-1,4-naphthoquinone with the ester enolate derived from ethyl -nitrophenylacetic acid, which rapid assembled the ABCD ring system of a pentacyclic pyrroloacridine, has been applied to the attempted synthesis of the marine natural product alpkinidine. The reaction of ethyl -nitrophenylacetic acid with 6,7-dichloro-2-methylisoquinoline-1,5,8(2)-trione, required to extend the model strategy to alpkinidine, was unfruitful, giving only complex mixtures. Efforts to direct the regiochemistry of the key Michael substitution step using 6-bromo-2-methylisoquinoline-1,5,8(2)-trione afforded an adduct sharing the complete carbon skeleton of alpkinidine, but this could not be elaborated to the natural product.

Organic-inorganic hybrid mixed-halide Zn and Cd tetra-halometallates with the 2-methyl-imidazo[1,5-]pyridinium cation.

Three isomorphous 0-D hybrid salts, namely, 2-methyl-imidazo[1,5-]pyridinium tri-chlorido-iodido-zincate(II), (CHN)[ZnClI] or [][ZnClI], (I), 2-methyl-imidazo[1,5-]pyridinium di-bromido-dichlorido-cadmate(II), (CHN)[CdBrCl] or [][CdBrCl], (II), and 2-methyl-imidazo[1,5-]pyridinium tri-chlorido-iodido-cadmate(II), (CHN)[CdClI] or [][CdClI], (III), are assembled from discrete 2-methyl-imidazo[1,5-]pyridinium cations, , and mixed-halide tetra-halometallate anions. In the three structures, there are two crystallographically non-equivalent cations that were modelled as being rotationally disordered by 180°. In the lattices of the three compounds, a disordered state exists involving partial substitution of Cl by I for sites 2-4 in (I), Br by Cl for all four sites in (II) and Cl by I for site 2 in (III).

Ni mol-ecular complex with a tetra-dentate amino-guanidine-derived Schiff base ligand: structural, spectroscopic and electrochemical studies and photoelectric response.

The new mol-ecular nickel(II) complex, namely, {4-bromo-2-[({'-[(2-oxidobenzylidene)amino]carbamimidoyl}imino)methyl]phenolato}nickel(II) ,-di-methyl-formamide solvate monohydrate, [Ni(CHBrNO)]·CHNO·HO, (I), crystallizes in the triclinic space group with one mol-ecule per asymmetric unit. The guanidine ligand is a product of Schiff base condensation between amino-guanidine, salicyl-aldehyde and 5-bromo-salicyl-aldehyde templated by Ni ions. The chelating ligand mol-ecule is deprotonated at the phenol O atoms and coordinates the metal centre through the two azomethine N and two phenolate O atoms in a -NiNO square-planar configuration [average(Ni-N/O) = 1.

A novel -vanillin Fe(III) complex catalytically active in C-H oxidation: exploring the magnetic exchange interactions and spectroscopic properties with different DFT functionals.

The novel complex [FeCl(L)(HO)] (1) was synthesized by interaction of iron(III) chloride with ethanol solution of -vanillin (HL) and characterized by IR, UV/Vis spectroscopy, thermogravimetry and single crystal X-ray diffraction analysis. The molecules of 1 in the solid state are joined into supramolecular dimeric units, where a set of strong hydrogen bonds predefines the structure of the dimer according to the "key-lock" principle. From the Hirshfield surface analysis the contribution of π⋯π stacking to the overall stabilization of the dimer was found to be negligible.

Organic-inorganic hybrid tetrachlorocadmates as promising fluorescent agents for cross-linked polyurethanes: synthesis, crystal structures and extended performance analysis.

The aim of this work is to apply organic-inorganic hybrid salts made of imidazo[1,5-]pyridinium-based cations and halometallate anions as fluorescent agents to modify cross-linked polyurethane (CPU) for the creation of flexible photoluminescent films. The use of ionic compounds ensures excellent dispersion of the luminescent components in the polymer matrix and prevents solid-state quenching. The absence of phase segregation makes it possible to fabricate uniformly luminescent films with a large area.

Ferro- antiferromagnetic exchange between two Ni(II) ions in a series of Schiff base heterometallic complexes: what makes the difference?

Three new NiII/ZnII heterometallics, [NiZnL'2(OMe)Cl]2 (1), [NiZnL''(Dea)Cl]2·2DMF (2) and [Ni2(H3L''')2(o-Van)(MeOH)2]Cl·[ZnCl2(H4L''')(MeOH)]·2MeOH (3), containing three-dentate Schiff bases as well as methanol or diethanolamine (H2Dea) or o-vanillin (o-VanH), all deprotonated, as bridging ligands were synthesized and structurally characterized. The Schiff base ligands were produced in situ from o-VanH and CH3NH2 (HL'), or NH2OH (HL"), or 2-amino-2-hydroxymethyl-propane-1,3-diol (H4L'''); a zerovalent metal (Ni and Zn in 1, Zn only in 2 and 3) was employed as a source of metal ions. The first two complexes are dimers with a Ni2Zn2O6 central core, while the third compound is a novel heterometallic cocrystal salt solvate built of a neutral zwitterionic ZnII Schiff base complex and of ionic salt containing dinuclear NiII complex cations.

Crystal structures of [μ-( , ,3a,7a)-1,3-bis-(2,7-di-cyclo-hexyl-naphthalen-1-yl)octa-hydro-1-benzo[]imidazolidin-2-yl-idene]chlorido-(η-1,5-cyclo-octa-diene)iridium di-chloro-methane monosolvate and [μ-( , ,3a,7a)-1,3-bis-(2,7-di-cyclo-hexyl-naphthalen-1-yl)octa-hydro-1-benzo[]imidazolidin-2-yl-idene]chlorido-(η-1,5-cyclo-octa-diene)iridium.

The title compounds, [Ir(CHN)Cl(CH)]·CHCl, (I), and [Ir(CHN)Cl(CH)], (II), represent the first two examples of hexa-hydro-benzo-imidazole-based -heterocyclic carbene (NHC) iridium complexes. The diastereomeric complexes differing only in their axial chirality, which could be separated column chromatography, show noticeable differences in their H NMR spectra. Compound (I) crystallizes in the monoclinic system (2) with two independent complexes and two half-occupied di-chloro-methane mol-ecules in the asymmetric unit, while compound (II) crystallizes in the ortho-rhom-bic system (222) with one complex in the asymmetric unit.

Crystal structure and characterization of a new copper(II) chloride dimer with meth-yl(pyridin-2-yl-methyl-idene)amine.

The new copper(II) complex, namely, di-μ-chlorido-bis-{chlorido-[meth-yl(pyri-din-2-yl-methyl-idene)amine-κ ,']copper(II)}, [CuCl(CHN)], (I), with the ligand 2-pyridyl-methyl--methyl-imine (, a product of Schiff base condensation between methyl-amine and 2-pyridine-carbaldehyde) is built of discrete centrosymmetric dimers. The coordination about the Cu ion can be described as distorted square pyramidal. The base of the pyramid consists of two nitro-gen atoms from the bidentate chelate [Cu-N = 2.

Crystal structure of imidazo[1,5-]pyridinium-based hybrid salt (CHN)[MnCl].

A new organic-inorganic hybrid salt [][MnCl] (I) where is the 2-methyl-3-(pyridin-2-yl)imidazo[1,5-]pyridinium cation, is built of discrete organic cations and tetra-chlorido-manganate(II) anions. The cation was formed in the oxidative cyclo-condensation of 2-pyridine-carbaldehyde and CHNH·HCl in methanol. The structure was refined as a two-component twin using (Spek, 2020 ▸) to de-twin the data.

Chemically and Mechanically Controlled Single-Molecule Switches Using Spiropyrans.

Developing molecular circuits that can function as the active components in electrical devices is an ongoing challenge in molecular electronics. It demands mechanical stability of the single-molecule circuit while simultaneously being responsive to external stimuli mimicking the operation of conventional electronic components. Here, we report single-molecule circuits based on spiropyran derivatives that respond electrically to chemical and mechanical stimuli.

Crystal structures of an imidazo[1,5-]pyridinium-based ligand and its (CHN)[CdI] hybrid salt.

The monocation product of the oxidative condensation-cyclization between two mol-ecules of pyridine-2-carbaldehyde and one mol-ecule of CHNH·HCl in methanol, 2-methyl-3-(pyridin-2-yl)imidazo[1,5-]pyridinium, was isolated in the presence of metal ions as bis-[2-methyl-3-(pyridin-2-yl)imidazo[1,5-]pyridin-2-ium] tetra-iodo-cadmate, (CHN)[CdI], (I), and the mixed chloride/nitrate salt, bis-[2-methyl-3-(pyridin-2-yl)imidazo[1,5-]pyridin-2-ium] 1.5-chlor-ide 0.5-nitrate trihydrate, 2CHN ·1.

Photophysical and biological investigation of phenol substituted rhenium tetrazolato complexes.

The synthesis, structural and photophysical characterisation of four tricarbonyl rhenium(i) complexes bound to 1,10-phenanthroline and a tetrazolato ancillary ligand are reported. The complexes are differentiated by the nature (hydroxy or methoxy) and position (meta or para) of the substituent attached to the phenyl ring in conjugation to the tetrazole ring. The complexes exhibit phosphorescence emission from triplet charge transfer excited states, with the maxima around 600 nm, excited state lifetime decays in the 200-300 ns range, and quantum yield values of 4-6% in degassed acetonitrile solutions.

Long magnetic relaxation time of tetracoordinate Co in imidazo[1,5-a]pyridinium-based (CHN)[CoCl] hybrid salt and [Co(CHN)Cl] molecular complex.

The novel organic-inorganic hybrid salt [L][CoCl] (1) and molecular complex [CoLCl] (2), where L is 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium cation, feature simple {CoCl} and {CoClN} tetrahedral environments of negligible (1) and a slightly higher distortion (2) that are responsible for rather low positive magnetic anisotropy of Co ion with D/hc = 12.1(6) (1) and 19.4(15) cm (2).

Crystal structure of bis-{μ-2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}bis-({2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}nickel(II)) involving different coordination modes of the same Schiff base ligand.

The structure of the title compound, [Ni(CHNO)], is built up by discrete centrosymmetric dimers. Two nitro-gen and three oxygen atoms of two Schiff base ligands singly deprotonated at the phenolate site form a square-pyramidal environment for each metal atom. The ligands are bonded differently to the metal centre: one of the phenolic O atoms is bound to one nickel atom, whereas another bridges the two metal atoms to form the dimer.

Carbon-Rich Trinuclear Octamethylferrocenophanes.

Several trinuclear ferrocenes are obtained by Friedel-Crafts reaction of octamethylferrocene with ferrocenoyl chloride and subsequent modifications. 1,1'-Diferrocenoyloctamethylferrocene (3) is transformed to the divinyl derivative (4a) by reaction with MeLi and AlCl. The reactive 4a cyclizes spontaneously to a [4]ferrocenophane with buta-1,3-diene handle (5) or in the presence of AlCl to a [3]ferrocenophane with propene handle (6).

Crystal structure of di-chlorido-bis-{μ-2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}{2-meth-oxy-6-[(methyl-imino)-meth-yl]phenolato}cadmium(II)cobalt(III) monohydrate.

The title compound, [CoCd(CHNO)Cl]·HO, is a solvatomorph of the corresponding hemihydrate recently published by us [Nesterova (2018 ▸). , , 171-184]. The current structure reveals different cell parameters and space group compared with the published one while both are monoclinic with almost the same cell volume.

Energy transfer between Eu and Nd in near-infrared emitting β-triketonate coordination polymers.

Isomorphous β-triketonate-based lanthanoid polymers containing tris(4-methylbenzoyl)methanide (mtbm) and Rb+ with formula {[Ln(Rb)(mtbm)4]2}n (Ln = Eu3+ and Nd3+) have been synthesised and structurally characterised. The photophysical properties for the Nd3+ complex presented relatively long lifetimes and high quantum yields in comparison with analogous β-diketonate complexes. Mixed lanthanoid complexes were also formed and their luminescence properties studied, with effective sensitisation of the 4F3/2 of Nd3+via the 5D0 of Eu3+, which is to the best of our knowledge the first example of Eu3+ to Nd3+ sensitisation in a structurally defined coordination complex or polymer.

Multicarbazole scaffolds for selective G-quadruplex binding.

Herein we report a new class of G-quadruplex stabilising ligands, multicarbazoles, which display high G-quadruplex DNA selectivity in the presence of 250 times excess duplex DNA. We report the synthesis of these compounds in moderate to high yields. Ligands in the series with optimal G-quadruplex selectivity contain an N-propylamino chain length where the amino functionalities are either pyrrolidine or piperidine.

Electronic and Steric Tuning of an Atropisomeric Disulfoxide Ligand Motif and Its Use in the Rh(I)-Catalyzed Addition Reactions of Boronic Acids to a Wide Range of Acceptors.

A novel chiral disulfoxide ligand pair bearing fluorine atoms at the 6 and 6' position of its atropisomeric backbone, ( M, S, S)- and ( P, S, S)- p-Tol-6F-BIPHESO, was synthesized. Complexation to a rhodium(I) precursor gave rise to μ-Cl- and μ-OH-bridged rhodium dimer complexes incorporating the new ( M, S, S)- p-Tol-6F-BIPHESO ligand, while its sibling ( P, S, S)- p-Tol-6F-BIPHESO was not complexed efficiently to the rhodium precursor. The performance of this disulfoxide ligand [( M, S, S)- p-Tol-6F-BIPHESO] in catalysis was tested in both 1,4- and 1,2-addition reactions of arylboronic acids.

Confirmation of the Revised Structure of Samoquasine A and a Proposed Structural Revision of Cherimoline.

The identity of the natural product samoquasine A has remained obscure since its isolation from custard apple seeds in 2000. One of the proposed structures, benzo[ f]phthalazin-4(3 H)-one, was prepared in two steps by regioselective ortho-lithiation/formylation of N, N-diisopropyl-2-naphthylamide, followed by cyclization with hydrazine, but was shown to be different from the natural product. Perlolidine, another candidate structure, was synthesized by a novel route involving a β-selective Heck reaction of butyl vinyl ether.