Mechanochemical Polyoxometalate Super-Reduction with Lithium Metal.

In this first systematic investigation of mechanochemical polyoxometalate (POM) reduction, (TBA)[PMoO] was reacted with equiv of lithium metal ( = 1-24) to generate products which were shown to be mixtures of electron-rich species. FTIR analysis revealed the lengthening/weakening of terminal Mo═O bonds with increasing levels of reduction, while EXAFS spectra indicated the onset of Mo-Mo bond formation at ∼ 8 and a significant structural change at > 12. Successive Mo reductions were monitored by XANES and XPS, and at = 24, results were consistent with the formation of at least one Mo-Mo bonded {Mo} triad together with Mo.

Mechanochemical Synthesis of a Sodium Anion Complex [Na(2,2,2-cryptand)Na] and Studies of Its Reactivity: Two-Electron and One-Electron Reductions.

Group 1 metal molecular chemistry is dominated by a +1 oxidation state, while a 0 oxidation state is widespread in the metals. A more exotic, yet still available, oxidation state of group 1 metal is -1, i.e.

Stereoselective Access to Diverse Alkaloid-Like Scaffolds via an Oxidation/Double-Mannich Reaction Sequence.

Sequential oxidative cleavage and double-Mannich reactions enable the stereoselective conversion of simple norbornenes into complex alkaloid-like structures. The products undergo a wide range of derivatization reactions, including regioselective enol triflate formation/cross-coupling sequences and highly efficient conversion to an unusual tricyclic 8,5,5-fused lactam. Overall, the process represents a formal one-atom aza-ring expansion with concomitant bridging annulation, making it of interest for the broader derivatization of alkene feedstocks.

Synthesis, structure and stereodynamics of atropisomeric -chloroamides.

Atropisomeric -chloroamides were efficiently accessed by electrophilic halogenation of -substituted secondary anilides. The stereodynamics of atropisomerism in these novel scaffolds was interrogated by detailed experimental and computational studies, revealing that racemization is correlated with amide isomerization. The stereoelectronic nature of the amide was shown to significantly influence racemization rates, with potentially important implications for other C-N atropisomeric scaffolds.

Lithium, sodium and potassium enolate aggregates and monomers: syntheses and structures.

In this , we report the syntheses and comparative structural studies of lithium, sodium, and potassium anthracen-9-yl enolates, as their aggregates (Li, Na: hexamer; K: tetramer) and ligand-stabilized monomers (for Li and Na). The monomers add new members to the rare collection of group-1 metal monomeric enolates. Moreover, the series covers different group-1 metal cations (Li, Na and K) and aggregate sizes, allowing comparative structural studies to elucidate how the metal identity and aggregate size influence the enolate structure.

A State of Independents: Rationalizing the High ' Crystal Structures of Shikimate Esters.

' is a parameter used to denote the number of symmetry-independent molecules in the asymmetric unit of a crystal structure. High ' (>1) crystal structures are relatively uncommon and are thought to arise through competition between intermolecular interactions of similar strength. As such high ' crystal structures are challenging to predict and new examples are valuable in improving understanding in the field.

Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells.

Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10 S cm upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10 S cm) while only costing an estimated $5/g.

Vesicles, fibres, films and crystals: A low-molecular-weight-gelator [Au(6-thioguanosine)]Cl which exhibits a co-operative anion-induced transition from vesicles to a fibrous metallo-hydrogel.

We describe a simple coordination compound of Au(I) and 6-thioguanosine, [Au(6-tGH)]Cl, that has a rich self-assembly chemistry. In aqueous solution, the discrete complex assembles into a supramolecular fibre and forms a luminescent hydrogel at concentrations above about 1 mM. Below this concentration, the macromolecular structure is a vesicle.

Reduction of K or Li in the Heterobimetallic Electride K[LiN(SiMe)]e.

Given their very negative redox potential (e.g., Li → Li(0), -3.

Stereoselective two-carbon ring expansion of allylic amines electronic control of palladium-promoted equilibria.

General methodologies enabling the two-carbon homologation of pyrrolidine and piperidine systems have yet to be developed. Herein we report that palladium-catalysed allylic amine rearrangements enable efficient two-carbon ring expansion of 2-alkenyl pyrrolidine and piperidines to their azepane and azocane counterparts. Conditions are mild, tolerant of a range of functional groups and the process can occur with high enantioretention.

A Window into the Workings of -BH Luminescence-Blue-Fluorescent Isomeric Pair 3,3'-Cl-BH and 3,4'-Cl-BH (and Others).

The action of AlCl on room-temperature tetrachloromethane solutions of -BH () results in a mixture of fluorescent isomers, 3,3'-Cl-BH () and 3,4'-Cl-BH (), together isolated in a 76% yield. Compounds and are capable of the stable emission of blue light under UV-excitation. In addition, small amounts of other dichlorinated isomers, 4,4'-Cl-BH (), 3,1'-Cl-BH (), and 7,3'-Cl-BH () were isolated, along with blue-fluorescent monochlorinated derivatives, 3-Cl-BH () and 4-Cl-BH (), and trichlorinated species 3,4,3'-Cl-BH () and 3,4,4'-Cl-BH ().

Monomeric lithium and sodium silylbenzyl complexes: syntheses, structures, and CO bond olefination.

Herein we report the syntheses, structures and reactivity studies of two new monomeric alkali metal silylbenzyl complexes stabilised by a tetradentate amine ligand, tris[2-(dimethylamino)ethyl]amine (MeTren). The two complexes, namely [MR'(MeTren)] (R': CH(Ph)(SiMe)) (2-Li: M = Li; 2-Na: M = Na), exhibit significant different coordination modes according to their metal identity (Li: σ-coordination; Na: π-coordination). Reactivity studies of 2-Li and 2-Na reveal that they are efficient in promoting a widely-used class of organic functional group interconversion: CO bond olefination of ketones, aldehydes and amides, to produce tri-substituted internal alkenes.

A thirty-year old mystery solved: identification of a new heptatungstate from non-aqueous solutions.

A new isopolyoxotungstate has been characterised, thirty years since the first spectroscopic evidence of its existence. The heptatungstate [WOH], containing a {W} lacunary Lindqvist unit fused to a ditungstate fragment, has significant stability and is only the third isopolytungstate structure to be obtained from non-aqueous systems.

Stereochemical Control of Secondary Benzamide-based BODIPY Emitters.

Aromatic amides can be used to construct light-harvesting materials with valuable optical properties. The amide bond is formed using well-known coupling agents in near quantitative yield, as illustrated here through the synthesis of two boron dipyrromethene derivatives bearing an amide linkage. The primary concern with acyl amides is rotation around the C-N bond, leading to cis and trans isomers.

Li vs Na: Divergent Reaction Patterns between Organolithium and Organosodium Complexes and Ligand-Catalyzed Ketone/Aldehyde Methylenation.

Organosodium chemistry is underdeveloped compared with organolithium chemistry, and all the reported organosodium complexes exhibit similar, if not identical, reactivity patterns to their lithium counterparts. Herein, we report a rare organosodium monomeric complex, namely, [Na(CHSiMe)(MeTren)] (-Na) (MeTren: tris[2-(dimethylamino)ethyl]amine) stabilized by a -dentate neutral amine ligand MeTren. Employing organo-carbonyl substrates (ketones, aldehydes, amides, ester), we demonstrated that -Na features distinct reactivity patterns compared with its lithium counterpart, [Li(CHSiMe)(MeTren)] (-Li).

Phosphido-borane-supported stannates.

The reactions between SnCl and three equivalents of the alkali metal phosphido-borane complexes [RP(BH)]M yield the corresponding tris(phosphido-borane)stannate complexes [LM{RP(BH)}Sn] [R = iPr, LM = (THF)Li (2Li), (EtO)Na (2Na), (EtO)K (2K); R = Ph, LM = (THF)Li (3Li), (THF)(EtO)Na (3Na), (THF)(EtO)K (3K); R = iPrPh, LM = (THF)Li (4Li)]. In each case X-ray crystallography reveals an anion consisting of a trigonal pyramidal tin centre coordinated by the P atoms of the phosphido-borane ligands. These tris(phosphido-borane)stannate anions coordinate to the alkali metal cations their BH hydrogen atoms in a variety of modes to give monomers, dimers, and polymers, depending on the alkali metal and the substituents at the phosphorus centres.

Elucidating Solution-State Coordination Modes of Multidentate Neutral Amine Ligands with Group-1 Metal Cations: Variable-Temperature NMR Studies.

Multidentate neutral amine ligands play vital roles in coordination chemistry and catalysis. In particular, these ligands are used to tune the reactivity of Group-1 metal reagents, such as organolithium reagents. Most, if not all, of these Group-1 metal reagent-mediated reactions occur in solution.