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When chiral compounds with low enantiomeric excess (ee, R:S=m:n) were absorbed into the void of the crystalline sponge (CS), enantiomerically pure [(R)m(S)n] chiral composites were formed, changing the centrosymmetric space group into non‐centrosymmetric one. The absolute configuration of the analyte compounds was elucidated with a reasonable Flack (Parsons) parameter value. This phenomenon is characteristic to the "post‐crystallization" in the pre‐determined CS crystalline lattice, seldom found in common crystallization where the crystalline lattice is defined by an analyte itself. The results highlight the potential of the CS method for absolute configuration determination of low ee samples, an often encountered situation in asymmetric synthesis studies. [ABSTRACT FROM AUTHOR]

When chiral compounds with low enantiomeric excess (ee, R:S=m:n) were absorbed into the void of the crystalline sponge (CS), enantiomerically pure [(R)m(S)n] chiral composites were formed, changing the centrosymmetric space group into non‐centrosymmetric one. The absolute configuration of the analyte compounds was elucidated with a reasonable Flack (Parsons) parameter value. This phenomenon is characteristic to the "post‐crystallization" in the pre‐determined CS crystalline lattice, seldom found in common crystallization where the crystalline lattice is defined by an analyte itself. The results highlight the potential of the CS method for absolute configuration determination of low ee samples, an often encountered situation in asymmetric synthesis studies. [ABSTRACT FROM AUTHOR]

The Industries need techniques for the rapid structure analysis of amino acid derivatives. The amino acid derivatives are sometimes produced as impurities in the industrial production processes, and cause toxicity problems. Herein, we report the crystalline sponge (CS) method analysis of variety of amino acids using a formyl group installed CS crystal. Most amino acids possess a primary amino group, which can form Schiff‐base with the formyl group under mild conditions. Thus, the formyl group installed CS crystal can efficiently capture the amino acids via Schiff‐base formation. We successfully analyzed derivatives of 18 proteogenic amino acids, 6 non‐proteogenic amino acids, and 4 dipeptides using the formyl group installed CS. We thus believe that the protocols shown in this study would serve the need of the industries. [ABSTRACT FROM AUTHOR]

Pd‐based molecular square Pd4L4 and triangle Pd3L3 represent the molecular ancestors of metal‐coordination polyhedra that have been an integral part of the field for the last 30 years. Conventional solution‐based reactions between cis‐protected Pd ions and 2,2′‐bipyridine exclusively give Pd4L4 and/or Pd3L3 as the sole products. We herein show that, under solvent‐free mechanochemical conditions, the self‐assembly energy landscape can be thermodynamically manipulated to form an elusive cyclic dimer Pd2L2 for the first time. In the absence of solvent, Pd2L2 is indefinitely stable in the solid‐state, but converts rapidly to its thermodynamic products Pd3L3 and Pd4L4 in solution, confirming Pd2L2 as a short‐lived kinetic species in the solution‐based self‐assembly process. Our results highlight how mechanochemistry grants access to a vastly different chemical space than available under conventional solution conditions. This provides a unique opportunity to isolate elusive species in self‐assembly processes that are too reactive to both "see" and "capture". [ABSTRACT FROM AUTHOR]

Pd‐based molecular square Pd4L4 and triangle Pd3L3 represent the molecular ancestors of metal‐coordination polyhedra that have been an integral part of the field for the last 30 years. Conventional solution‐based reactions between cis‐protected Pd ions and 2,2′‐bipyridine exclusively give Pd4L4 and/or Pd3L3 as the sole products. We herein show that, under solvent‐free mechanochemical conditions, the self‐assembly energy landscape can be thermodynamically manipulated to form an elusive cyclic dimer Pd2L2 for the first time. In the absence of solvent, Pd2L2 is indefinitely stable in the solid‐state, but converts rapidly to its thermodynamic products Pd3L3 and Pd4L4 in solution, confirming Pd2L2 as a short‐lived kinetic species in the solution‐based self‐assembly process. Our results highlight how mechanochemistry grants access to a vastly different chemical space than available under conventional solution conditions. This provides a unique opportunity to isolate elusive species in self‐assembly processes that are too reactive to both "see" and "capture". [ABSTRACT FROM AUTHOR]

The reaction of C2H4 and β-SiH containing azasilazirconacycle Cp2Zr{κ2-N(SiHMe2)SiHMeCH2} (3), formed via a γ-abstraction reaction of Cp2Zr{N(SiHMe2)2}H (1), follows an unusual pathway in which a rare σ-bond metathesis reaction of ethylene generates a vinyl intermediate. That species undergoes a β-hydrogen abstraction under the reaction conditions to form a zirconium silanimine ethylene adduct en route to the metallacyclopentane product. [ABSTRACT FROM AUTHOR]

The new homoleptic rare earth compound [Y(C(SiHMe2)3)3] (2) is prepared in 82% yield by salt metathesis of YCl3 and 3 equivalents of [KC(SiHMe2)3] (1); two α-agostic Y· · ·(H-Si) interactions are observed for each C(SiHMe2)3 ligand in 2, giving six agostic interactions per yttrium(III) center. [ABSTRACT FROM AUTHOR]

Due to the reversible nature of coordination bonds and solvation effect, coordination self‐assembly pathways are often difficult to elucidate experimentally in solution, as intermediates and products are in constant equilibration. The present study shows that some of these transient and high‐energy self‐assembly intermediates can be accessed by means of ball‐milling approaches. Among them, highly aqueous‐unstable Pd3L11 and Pd6L14 open‐cage intermediates of the framed Fujita Pd6L14 cage and Pd2L22, Pd3L21 and Pd4L22 intermediates of Mukherjee Pd6L24 capsule are successfully trapped in solid‐state, where Pd=tmedaPd2+, L1=2,4,6‐tris(4‐pyridyl)‐1,3,5‐triazine and L2=1,3,5‐tris(1‐imidazolyl)benzene). Their structures are assigned by a combination of solution‐based characterization tools such as standard NMR spectroscopy, DOSY NMR, ESI‐MS and X‐ray diffraction. Collectively, these results highlight the opportunity of using mechanochemistry to access unique chemical space with vastly different reactivity compared to conventional solution‐based supramolecular self‐assembly reactions. [ABSTRACT FROM AUTHOR]

Recently, polymer mechanochemistry has attracted much scientific interest due to its potential to develop degradable polymers. When the two ends of a polymer chain experience a linear pulling stress, molecular strain builds up, at sufficiently strong force, a bond scission of the weakest covalent bond results. In contrast, bond‐breaking events triggered by conformational stress are much less explored. Here, we discovered that a Zn salen complex would undergo conformational switching upon allosteric complexation with alkanediammonium guests. By controlling the guest chain length, the torsional strain experienced by Zn complex can be modulated to induce bond cleavage with chemical stimulus, and reactivity trend is predicted by conformational analysis derived by DFT calculation. Such strain‐release reactivity by a Zn(salen) complex initiated by guest binding is reminiscent of conformation‐induced reactivity of enzymes to enable chemical events that are otherwise inhibited. [ABSTRACT FROM AUTHOR]

Recently, polymer mechanochemistry has attracted much scientific interest due to its potential to develop degradable polymers. When the two ends of a polymer chain experience a linear pulling stress, molecular strain builds up, at sufficiently strong force, a bond scission of the weakest covalent bond results. In contrast, bond‐breaking events triggered by conformational stress are much less explored. Here, we discovered that a Zn salen complex would undergo conformational switching upon allosteric complexation with alkanediammonium guests. By controlling the guest chain length, the torsional strain experienced by Zn complex can be modulated to induce bond cleavage with chemical stimulus, and reactivity trend is predicted by conformational analysis derived by DFT calculation. Such strain‐release reactivity by a Zn(salen) complex initiated by guest binding is reminiscent of conformation‐induced reactivity of enzymes to enable chemical events that are otherwise inhibited. [ABSTRACT FROM AUTHOR]

Chiral vicinal diamines, a unique class of optically-active building blocks, play a crucial role in material design, pharmaceutical, and catalysis. Traditionally, their syntheses are all solvent-based approaches, which make organic solvent an indispensable part of their production. As part of our program aiming to develop chemical processes with reduced carbon footprints, we recently reported a highly practical and environmentally-friendly synthetic route to chiral vicinal diamines by solvent-free mechanochemical diaza-Cope rearrangement. We herein showed that a new protocol by co-milling with common laboratory solid additives, such as silica gel, can significantly enhance the efficiency of the reaction, compared to reactions in the absence of additives. One possible explanation is the Lewis acidic nature of additives that accelerates a key Schiff base formation step. Reaction monitoring experiments tracing all the reaction species, including reactants, intermediates, and product, suggested that the reaction profile is distinctly different from ball-milling reactions without additives. Collectively, this work demonstrated that additive effect is a powerful tool to manipulate a reaction pathway in mechanochemical diazo-Cope rearrangement pathway, and this is expected to find broad interest in organic synthesis using mechanical force as an energy input. [ABSTRACT FROM AUTHOR]

Synthesis and reactivity of monomeric magnesium and zinc silyl compounds ToMM–Si(SiHMe2)3 and ToMM–Si(SiMe3)3 are described (ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). The magnesium compounds react slowly with water and air, while the zinc compounds are inert. With CO2, ToMMg–Si(SiHMe2)3 provides ToMMgO2CSi(SiHMe2)3 through CO2 insertion, whereas ToMZn–Si(SiHMe2)3 affords ToMZnOCHO. [ABSTRACT FROM AUTHOR]

Abstract: This work undertakes, we believe for the first time, a study of the chemistry of alkyl halides in Na0 treated zeolites. It concludes that untreated zeolites do nucleophilic chemistry to the degree that the host is electron donating. It concludes that Na0 treated zeolites do a mixture of nucleophilic, electron-transfer, and free radical chemistry. Zeolites NaX and NaY and their Na0 treated forms (Na0/NaX and Na0/NaY) were exposed to linear1-haloalkanes (Cl, Br, I). NaY is inert in all cases. Framework alkoxy and halide ion are formed in NaX from the Br- and I-alkanes in an electrophilic attack of framework oxygen on the alkyl halide, while the leaving of the halide ion is assisted by the electrostatic attraction of the NaX site III or III′ Na ions. In Na0NaX and Na0/NaY direct reaction of Na0 with the alkyl bromide or iodide yields a larger alkane and halide ion, probably via a free radical mechanism involving two Na0 and two alkyl halides. The NaX–alkyl chloride chemistry includes exclusively or partly dehydrohalogenation, yielding 1-alkenes and chloride ion. Na0/NaX or Na0/NaY–alkyl chloride dehydrohalogenation chemistry yields chloride with 2-alkenes in low yield and alkanes in higher yields. 1-Chloropropane yields the framework propoxy and propene from NaX and yields these products plus other olefins from Na0/NaX. Overall the yields and reactivity fall into a pattern of Lewis basicity increasing in the order NaY