Diverse Multinuclear Alkali Metallated (Li, Na, K, Rb, Cs) Family of the 1,3,5-tris-2-aminopyridyl-2,4,6-triethylbenzene Framework.

Literature on Group One organoelement chemistry is dominated by lithium, though sodium and potassium also feature prominently, whereas rubidium and caesium are rarely mentioned. With recent breakthroughs hinting that organoelement compounds of these two heavier metals can perform better than their lighter congeners in particular applications, important advantages could be missed unless complete sets of alkali metals are included in studies. Here, we report the synthesis and characterisation of a complete set of multi-alkali-metallated molecular compounds of the 1,3,5-tris[(4,6-dimethylpyridin-2-yl)aminomethyl]-2,4,6-triethylbenzene framework.

Toward On-Demand Polymorphic Transitions of Organic Crystals via Side Chain and Lattice Dynamics Engineering.

Controlling polymorphism, namely, the occurrence of multiple crystal forms for a given compound, is still an open technological challenge that needs to be addressed for the reliable manufacturing of crystalline functional materials. Here, we devised a series of 13 organic crystals engineered to embody molecular fragments undergoing specific nanoscale motion anticipated to drive cooperative order-disorder phase transitions. By combining polarized optical microscopy coupled with a heating/cooling stage, differential scanning calorimetry, X-ray diffraction, low-frequency Raman spectroscopy, and calculations (density functional theory and molecular dynamics), we proved the occurrence of cooperative transitions in all the crystalline systems, and we demonstrated how both the molecular structure and lattice dynamics play crucial roles in these peculiar solid-to-solid transformations.

Salt forms of amides: protonation of acetanilide.

Treating the amide acetanilide (N-phenylacetamide, CHNO) with aqueous strong acids allowed the structures of five hemi-protonated salt forms of acetanilide to be elucidated. N-(1-Hydroxyethylidene)anilinium chloride-N-phenylacetamide (1/1), [(CHNO)H][Cl], and the bromide, [(CHNO)H][Br], triiodide, [(CHNO)H][I], tetrafluoroborate, [(CHNO)H][BF], and diiodobromide hemi(diiodine), [(CHNO)H][IBr]·0.5I, analogues all feature centrosymmetric dimeric units linked by O-H.

A monoclinic polymorph of chloro-thia-zide.

A new polymorph of the diuretic chloro-thia-zide, 6-chloro-1,1-dioxo-2-1,2,4-benzo-thia-zine-7-sulfonamide, CHClNOS, is described. Crystallized from basic aqueous solution, this monoclinic polymorph is found to be less thermodynamically favoured than the known triclinic polymorph and to feature only N-H⋯O type inter-molecular hydrogen bonds as opposed to the N-H⋯O and N-H⋯N type hydrogen bonds found in the 1 form.

Application of Bis(amido)alkyl Magnesiates toward the Synthesis of Molecular Rubidium and Cesium Hydrido-magnesiates.

Rubidium and cesium are the least studied naturally occurring s-block metals in organometallic chemistry but are in plentiful supply from a sustainability viewpoint as highlighted in the periodic table of natural elements published by the European Chemical Society. This underdevelopment reflects the phenomenal success of organometallic compounds of lithium, sodium, and potassium, but interest in heavier congeners has started to grow. Here, the synthesis and structures of rubidium and cesium bis(amido)alkyl magnesiates [(AM)MgN'alkyl], where N' is the simple heteroamide N(SiMe)(Dipp), and alkyl is Bu or CHSiMe, are reported.

Mechanistic Basis of the Cu(OAc) Catalyzed Azide-Ynamine (3 + 2) Cycloaddition Reaction.

The Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction is used as a ligation tool throughout chemical and biological sciences. Despite the pervasiveness of CuAAC, there is a need to develop more efficient methods to form 1,4-triazole ligated products with low loadings of Cu. In this paper, we disclose a mechanistic model for the ynamine-azide (3 + 2) cycloadditions catalyzed by copper(II) acetate.

Synthesis and Reactivity of Bis-tris(pyrazolyl)borate Lanthanide/Aluminum Heterobimetallic Trihydride Complexes.

Molecular heterobimetallic hydride complexes of lanthanide (Ln) and main-group (MG) metals exhibit chemical properties unique from their monometallic counterparts and are highly reactive species, making their synthesis and isolation challenging. Herein, molecular Ln/Al heterobimetallic trihydrides [Ln(Tp)(μ-H)Al(H)(N″)] [; Ln = Y, Sm, Dy, Yb; Tp = hydrotris(1-pyrazolyl)borate; N″ = N(SiMe)] have been synthesized by facile insertion of aminoalane [MeN·AlH] into the Ln-N amide bonds of [Ln(Tp)(N″)] (). Thus, this is a simple synthetic strategy to access a range of Ln/Al hydrides.

Synthesis, characterisation, and catalytic application of a soluble molecular carrier of sodium hydride activated by a substituted 4-(dimethylamino)pyridine.

Recently main group compounds have stepped into the territory of precious transition metal compounds with respect to utility in the homogeneous catalysis of fundamentally important organic transformations. Inspired by the need to promote more sustainability in chemistry because of their greater abundance in nature, this change of direction is surprising since main group metals generally do not possess the same breadth of reactivity as precious transition metals. Here, we introduce the dihydropyridylsodium compound, Na-1,2-tBu-DH(DMAP), and its monomeric variant [Na-1,2-tBu-DH(DMAP)]·MeTREN, and demonstrate their effectiveness in transfer hydrogenation catalysis of the representative alkene 1,1-diphenylethylene to the alkane 1,1-diphenylethane using 1,4-cyclohexadiene as hydrogen source [DMAP = 4-dimethylaminopyridine; MeTREN = tris(N,N-dimethyl-2-aminoethyl)amine].

Improving the gas sorption capacity in lantern-type metal-organic polyhedra by a scrambled cage method.

The synthesis of multivariate metal-organic frameworks (MOFs) is a well-known method for increasing the complexity of porous frameworks. In these materials, the structural differences of the ligands used in the synthesis are sufficiently subtle that they can each occupy the same site in the framework. However, multivariate or ligand scrambling approaches are rarely used in the synthesis of porous metal-organic polyhedra (MOPs) - the molecular equivalent of MOFs - despite the potential to retain a unique intrinsic pore from the individual cage while varying the extrinsic porosity of the material.

Isostructural behaviour in ammonium and potassium salt forms of sulfonated azo dyes.

The structures of five ammonium salt forms of monosulfonated azo dyes, derivatives of 4-(2-phenyldiazen-1-yl)benzenesulfonate, with the general formula [NH][OS(CH)NN(CH)RR']·XHO [R = OH, NH or N(CHOH); R' = H or OH] are presented. All form simple layered structures with alternating hydrophobic (organic) and hydrophilic (cation, solvent and polar groups) layers. To assess for isostructural behaviour of the ammonium cation with M ions, the packing of these structures is compared with literature examples.

Modification of a Common β-diketiminate NacNac Framework via Sequential Lithiation and Small Molecule Insertion.

A widely utilised class of ligands in synthesis and catalysis, β-diketiminate (BDI) or NacNac compounds were initially considered innocent in the sense that they remained intact in all their applications. That changed when the γ-C-H unit of their NCCCN backbone was found to engage in reactions with electrophiles. Here, we show that this special reactivity can be used advantageously to prepare tripodal modifications of the common NacNac ligand derived from 2,6-diisopropylphenyl-β-methyldiketimine [NacNacH (Me, Dipp)].

Isolable rubidium and caesium derivatives of common organic carbonyl compounds.

Light alkali metal (Li, Na, K) amides have a long history of synthetic utility, but heavier (Rb, Cs) congeners have barely been studied. This study reveals remarkable structurally complex outcomes of reacting AM(HMDS) (AM = Rb, Cs; HMDS = hexamethyldisilazide) with benzaldehyde and acetophenone. Though complicated, reactions give a diversity of eye-catching isolated products, an enolate with a hexagonal prismatic network, two dienolates with distinct extended ladder motifs, and two β-imino-alkoxides comprising zig-zag chains of metal-oxygen bonds in infinite cages.

A Hierarchy of Ligands Controls Formation and Reaction of Aryl Radicals in Pd-Catalyzed Ground-State Base-Promoted Coupling Reactions.

Palladium salts and complexes were tested separately and in the presence of added ligands as potential sources of aryl radicals in ground-state coupling reactions of aryl halide with arenes under basic conditions (KOBu). Our recently developed assay for aryl radicals was employed to test for aryl radicals. In this assay, aryl radicals derived from the test substrate, 1-iodo-2,6-dimethylbenzene , undergo base-promoted homolytic aromatic substitution (BHAS) with benzene to produce 2,6-dimethylbiphenyl and biphenyl in an approximately 1:4 ratio as well as -xylene The biphenyl arises from a diagnostic radical transfer reaction with the solvent benzene.

Atom-economic access to cationic magnesium complexes.

Cationic alkaline-earth complexes attract interest for their enhanced Lewis acidity and reactivity compared with their neutral counterparts. Synthetic protocols to these complexes generally utilize expensive specialized reagents in reactions generating multiple by-products. We have studied a simple ligand transfer approach to these complexes using (NacNac)MgR and ER (NacNac = β-diketiminate anion; E = group 13 element; R = aryl/amido anion) which demonstrates high atom economy, opening up the ability to target these species in a more sustainable manner.

Three Oxidative Addition Routes of Alkali Metal Aluminyls to Dihydridoaluminates and Reactivity with CO.

Three distinct routes are reported to the soluble, dihydridoaluminate compounds, AM[Al(NON )(H) ] (AM=Li, Na, K, Rb, Cs; [NON ] =[O(SiMe NDipp) ] ; Dipp=2,6-iPr C H ) starting from the alkali metal aluminyls, AM[Al(NON )]. Direct H hydrogenation of the heavier analogues (AM=Rb, Cs) produced the first examples of structurally characterized rubidium and caesium dihydridoaluminates, although harsh conditions were required for complete conversion. Using 1,4-cyclohexadiene (1,4-CHD) as an alternative hydrogen source in transfer hydrogenation reactions provided a lower energy pathway to the full series of products for AM=Li-Cs.

Enantiopure Dinaphtho[2,3-b:2,3-f]thieno[3,2-b]thiophenes: Reaching High Magnetoresistance Effect in OFETs.

Chiral molecules are known to behave as spin filters due to the chiral induced spin selectivity (CISS) effect. Chirality can be implemented in molecular semiconductors in order to study the role of the CISS effect in charge transport and to find new materials for spintronic applications. In this study, the design and synthesis of a new class of enantiopure chiral organic semiconductors based on the well-known dinaphtho[2,3-b:2,3-f]thieno[3,2-b]thiophene (DNTT) core functionalized with chiral alkyl side chains is presented.

Alkali Metal Dihydropyridines in Transfer Hydrogenation Catalysis of Imines: Amide Basicity versus Hydride Surrogacy.

Catalytic reduction of a representative set of imines, both aldimines and ketimines, to amines has been studied using transfer hydrogenation from 1,4-dicyclohexadiene. Unusually, this has been achieved using s-block pre-catalysts, namely 1-metallo-2-tert-butyl-1,2-dihydropyridines, 2-tBuC H NM, M(tBuDHP), where M=Li-Cs. Reactions have been monitored in C D and tetrahydrofuran-d (THF-d ).

Porous Metal-Organic Cages Based on Rigid Bicyclo[2.2.2]oct-7-ene Type Ligands: Synthesis, Structure, and Gas Uptake Properties.

Three new ligands containing a bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxydiimide unit have been used to assemble lantern-type metal-organic cages with the general formula [Cu L ].

Structural and Synthetic Insights on Oxidative Homocouplings of Alkynes Mediated by Alkali-Metal Manganates.

Exploiting bimetallic cooperation alkali-metal manganate (II) complexes can efficiently promote oxidative homocoupling of terminal alkynes furnishing an array of conjugated 1,3-diynes. The influence of the alkali-metal on these C-C bond forming processes has been studied by preparing and structurally characterizing the alkali-metal tetra(alkyl) manganates [(TMEDA) Na Mn(CH SiMe ) ] and [(PMDETA) K Mn(CH SiMe ) ]. Reactivity studies using phenylacetylene as a model substrate have revealed that for the homocoupling to take place initial metalation of the alkyne is required.

Serendipitous Enhancement of the Dimensionality in Diketopyrrolopyrroles through O-Substitution.

We report for the first time the crystal structure of an O-substituted diketopyrrolopyrrole and further evaluate computationally the ability of this higher-dimensionality system to act as a charge transfer mediator in optoelectronic devices.

Synthesis, Characterization, and Structural Analysis of [Al(NON)(H)(SiHPh)] ( = Li, Na, K, Rb, Cs) Compounds, Made Via Oxidative Addition of Phenylsilane to Alkali Metal Aluminyls.

We report the oxidative addition of phenylsilane to the complete series of alkali metal () aluminyls [{Al(NON)}] ( = Li, Na, K, Rb, and Cs). Crystalline products () have been isolated as ether or THF adducts, [(L)][Al(NON)(H)(SiHPh)] ( = Li, Na, K, Rb, L = EtO, = 1; = Cs, L = THF, = 2). Further to this series, the novel rubidium rubidiate, [{Rb(THF)}(Rb{Al(NON)(H)(SiHPh)})] [Rb{Al(NON)(H)(SiHPh)}], was isolated during an attempted recrystallization of Rb[Al(NON)(H)(SiHPh)] from a hexane/THF mixture.