Squeezing CC Bonds

Huntley, D. R.; Μαρκόπουλος, Γεώργιος; Donovan, Patrick; Scott, Lawrence T.; Hoffmann, Roald

doi:10.1002/anie.200502721

Cited by 50 publications

(37 citation statements)

References 22 publications

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“…According to the bond length C21ÀC22 of 1.431 , a single bond is appropriate to describe the CÀC bonding properties (C sp ÀC sp 2 % 1.43 ). [28] In conclusion, structure N5 with a double bond C21=C22 contributes less to describe the resonance structure. The planar character of the anion and the delocalized negative charge in the tetrazolide ring confirm a 6p-aromatic compound, isoelectronic to the well-known cyclopentadienide anion.…”

Section: Thermal Characterizationmentioning

confidence: 87%

Synthesis and Characterization of 5‐Cyanotetrazolide‐Based Ionic Liquids

Bergholz

Oelkers

Huber

et al. 2014

Chemistry A European J

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New salts based on imidazolium, pyrrolidinium, phosphonium, guanidinium, and ammonium cations together with the 5-cyanotetrazolide anion [C2 N5 ](-) are reported. Depending on the nature of cation-anion interactions, characterized by XRD, the ionic liquids (ILs) have a low viscosity and are liquid at room temperature or have higher melting temperatures. Thermogravimetric analysis, cyclic voltammetry, viscosimetry, and impedance spectroscopy display a thermal stability up to 230 °C, an electrochemical window of 4.5 V, a viscosity of 25 mPa s at 20 °C, and an ionic conductivity of 5.4 mS cm(-1) at 20 °C for the IL 1-butyl-1-methylpyrrolidinium 5-cyanotetrazolide [BMPyr][C2 N5 ]. On the basis of these results, the synthesized compounds are promising electrolytes for lithium-ion batteries.

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Section: Thermal Characterizationmentioning

confidence: 87%

Synthesis and Characterization of 5‐Cyanotetrazolide‐Based Ionic Liquids

Bergholz

Oelkers

Huber

et al. 2014

Chemistry A European J

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“…compression, 54 generate substantially different considerations) to specific bonds. The first point to mention is that the forces generated in a polymer under tension are (to first order) restricted to the polymer main chain, and therefore the primary mechanochemical coupling is restricted to the bonds that are within the polymer main chain.…”

Section: Steve Craigmentioning

confidence: 99%

From molecular mechanochemistry to stress-responsive materials

2011

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Current activity in, and future prospects for, the incorporation of mechanochemically active functional groups (''mechanophores'') into polymers is reviewed. This area of research is treated in the context of two categories. The first category is the development of new chemistry in the service of material science, through the design and synthesis of mechanophores to provide stress-sensing and/or stress-responsive elements in materials. The second category is the reverse-the development of new material architectures that efficiently transmit macroscopic forces to targeted molecules in order to generate chemical reactivity that is inaccessible by other means. IntroductionThe mechanical forces typical of daily life have the potential to induce dramatic reactivity at the molecular level. The force between an infant's clenched finger and thumb, for example, is more than ten billion times that of the force between atoms in a carbon-carbon bond. Not only are macroscopic forces many orders of magnitude greater than atomic forces, they are also directional, and therefore differ from conventional forms of energy input such as heat and light. In the past four years, several studies have demonstrated that macroscopic mechanical forces can be harnessed at the molecular level, creating a new tool for the organic and materials chemist alike. Broadly, the opportunities in this area can be divided into two categories. First, there is the opportunity to develop new chemistry in the service of material science by designing and synthesizing mechanically activated functional groups (''mechanophores'') and incorporating them as stress-sensing and/or stress-responsive elements in materials. The second opportunity is the complement of the first-the development of new material architectures that efficiently transmit macroscopic forces to targeted molecules and, in so doing, open up a world of chemical reactivity that is inaccessible by other means. We will refer to these as ''chem / mat'' and ''mat / chem'' mechanochemistry, respectively (Fig. 1). The field of mechanochemistry therefore touches on materials chemistry from the point of view of each of its principle progenitors with potential utility in areas ranging from stoichiometric reactivity and catalysis to stress-responsive and selfhealing polymers.We see the greatest opportunities in mechanochemistry arising from situations in which the mechanical force is directly applied to the mechanophore, so that a directional coupling between the vector of applied force and the reaction of interest is possible. The focus of this paper, then, will be on the mechanochemistry of polymers under tension, where the mechanical coupling is most obvious and, therefore, most amenable to the chemist's intuition. Other aspects of mechanochemistry, such as those involved in the milling of crystals, metals, and alloys, 1 are well known and important fields, but they will not be discussed here. A comprehensive review of mechanochemistry in polymers has been published recently by Caruso et al., 2 and it is ...

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“…[25] Can one make CÀC bonds that are really short? [26] Its just so much fun to explore that chemical playground, asking "What if ?" or "Why not?"…”

Section: Psychological Reasonsmentioning

confidence: 99%

Learning from Molecules in Distress

Hoffmann

Hopf

2008

Angew Chem Int Ed

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Going to extremes: Deformed molecules with “planar” carbon atoms, orthogonal double bonds, nonlinear triple bonds, and aromatic rings distorted into a boat structure have interested chemists for decades. This essay traces the reasons for this fascination, and finds them in the psyche of the researcher: the wish to transgress the limits of normalcy, the insatiable curiosity to extend the limits of method and mind, and the eternal human joy to find something new while playing.

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Squeezing CC Bonds

Cited by 50 publications

References 22 publications

Synthesis and Characterization of 5‐Cyanotetrazolide‐Based Ionic Liquids

Synthesis and Characterization of 5‐Cyanotetrazolide‐Based Ionic Liquids

From molecular mechanochemistry to stress-responsive materials

Learning from Molecules in Distress

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