Nature of weak inter- and intramolecular interactions in crystals 4. Bifurcated N—H...N bond in a crystal of 3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine

Lyubetsky, Denis V.; Sheremetev, Aleksei B.; Antipin, M. Yu.

doi:10.1007/s11172-005-0336-y

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…The yield of compound 1 was 1.676 g (93%). 1 11 The structure was solved by direct methods with the use of successive electron density maps. All hydrogen atoms were re vealed from difference electron density maps.…”

Section: Methodsmentioning

confidence: 99%

Nature of weak inter- and intramolecular interactions in crystals. 5. Interactions Na...H—B in a crystal of sodium salt of charge-compensated nido-carborane [9-SMe2-7,8-C2B9H10]−

et al. 2005

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The character of electron density distribution in the C 2 B 3 open face, the influence of the SMe 2 group on the character of electron density distribution, and the nature of the so dium-anion interaction were studied based on the data of high resolution X ray diffraction study of crystals of the sodium salt of charge compensated nido carborane [9 SMe 2 7,8 C 2 B 9 H 10 ] -and quantum chemical calculations for the Na...H-B bonded dimer, the isolated [9 SMe 2 7,8 C 2 B 9 H 10 ] -anion, and the [7,8 C 2 B 9 H 10 ] 2-dianion. The character of electron density distribution in the C 2 B 3 open face is analogous to the electron distribution in the cyclopentadienyl ligand. In nido carborane, a substantial charge redistribution takes place compared to that observed in the closo analogs. The topological analysis of the electron density distribution function demonstrated that the cation-anion interactions are determined pre dominantly by Na...H-B contacts. The total energy of these contacts in the {[9 SMe 2 7,8 C 2 B 9 H 10 ]Na(thf) 2 } 2 dimer estimated from X ray diffraction data is 11.74 kcal mol -1 .Key words: charge compensated nido carboranes, isolobality, nido carborane salts with alkali metals, quantum chemical calculations, Na...B-H contacts, electron density distribu tion, topological theory of Atoms in Molecules, high resolution X ray diffraction study.Alkali metal salts with anionic 11 vertex nido carbo ranes are widely used as starting compounds in the syn thesis of metallocarboranes. 2-5 However, their structures both in solution and in the solid state remained unknown until very recently. In the last years, it has been demon strated that these salts exist predominantly as contact ion pairs both in crystals 6,7 and in solution. 8 The coordination mode of cations in anionic nido car boranes depends substantially on the cation size. In lithium salts with the charge compensated [9 L 7,8 C 2 B 9 H 10 ] -anions (L = SMe 2 or NMe 3 ) and the [7,8 C 2 B 9 H 10 ] 2-dianions, η 5 coordination at the C 2 B 3 open face of the carborane is the main coordination mode, whereas so dium salts are characterized by exo coordination at the B(10)B(11)B(6) face. 6,7In the case of exo coordination, the sodium-anion interaction can be either analogous to interactions in exo nido Os, Ru, 9,10 and Rh 11 complexes with 3c-2e metal...H-B bonds or occur through an interaction of the sodium cation with the electron density localized at the center of the triangular face and on the boron atoms.Actually, the negative charge in carboranes is distributed not only between the hydrogen atoms of the B-H bonds 12 but also over the surface of the triangular face. 13-15 From the geometric standpoint (Na...B and Na...H distances), 6 both types of interactions in sodium salts with the [9 L 7,8 C 2 B 9 H 10 ] -anion are equally probable. In struc tural studies 16,17 of small and medium sized carborane salts with alkali and alkaline earth metal cations, it was hypothesized that the cations interact predominantly with boron atoms. In contrast, Na...H-B ...

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Section: Methodsmentioning

confidence: 99%

Nature of weak inter- and intramolecular interactions in crystals. 5. Interactions Na...H—B in a crystal of sodium salt of charge-compensated nido-carborane [9-SMe2-7,8-C2B9H10]−

et al. 2005

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“…However, a refinement of these parameters is not possible for systems substantially larger than simple amino acids, owing to the problem of dependent parameters in the multipole model. Usually, the treatment of H atoms does not go beyond isotropic ADPs (Munshi et al, 2008;Benabicha et al, 2000;Pichon-Pesme et al, 2000;Kalinowski et al, 2007;Wagner & Luger, 2001;Lyssenko et al, 2005) and dipolar terms within the multipole model (Grabowsky et al, 2007;Wagner et al, 2004;Checinska et al, 2006;Dominiak et al, 2006). The extended multipole model will thus remain an exceptional case, to be encountered for crystals of small molecules only.…”

Section: Than In Defmentioning

confidence: 99%

Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM)

Netzel

Smaalen

2009

Acta Crystallogr Sect B

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Charge densities have been determined by the Maximum Entropy Method (MEM) from the high-resolution, low-temperature (T ≃ 20 K) X-ray diffraction data of six different crystals of amino acids and peptides. A comparison of dynamic deformation densities of the MEM with static and dynamic deformation densities of multipole models shows that the MEM may lead to a better description of the electron density in hydrogen bonds in cases where the multipole model has been restricted to isotropic displacement parameters and low-order multipoles (l max = 1) for the H atoms. Topological properties at bond critical points (BCPs) are found to depend systematically on the bond length, but with different functions for covalent C—C, C—N and C—O bonds, and for hydrogen bonds together with covalent C—H and N—H bonds. Similar dependencies are known for AIM properties derived from static multipole densities. The ratio of potential and kinetic energy densities |V(BCP)|/G(BCP) is successfully used for a classification of hydrogen bonds according to their distance d(H...O) between the H atom and the acceptor atom. The classification based on MEM densities coincides with the usual classification of hydrogen bonds as strong, intermediate and weak [Jeffrey (1997). An Introduction to Hydrogen Bonding. Oxford University Press]. MEM and procrystal densities lead to similar values of the densities at the BCPs of hydrogen bonds, but differences are shown to prevail, such that it is found that only the true charge density, represented by MEM densities, the multipole model or some other method can lead to the correct characterization of chemical bonding. Our results do not confirm suggestions in the literature that the promolecule density might be sufficient for a characterization of hydrogen bonds.

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“…A significant distortion of the tetrazine cycle was also noted in asymmetrically substituted (3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazines. [48,49]…”

Section: Structures Of New Compoundsmentioning

confidence: 99%

Synthesis and Physicochemical Properties of Energetic 1,2,4,5‐Tetrazinyl Derivatives of 5‐Nitro‐2,4‐dihydro‐1,2,4‐triazol‐3‐one

et al. 2021

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By replacing the pyrazolyl fragment in 3,6-bis(3,5-dimethyl-1Hpyrazol-1-yl)-1,2,4,5-tetrazine with 3-nitro-1,2,4-triazol-5-one (NTO), both mono-and disubstitution products have been synthesized. Further interaction of the obtained compounds with O-and N-nucleophiles led to the preparation of a number of polynitrogen tetrazine derivatives, including 2-[6-amino-1,2,4,5-tetrazin-3-yl]-5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one and 5-nitro-2-[6-(1H-tetrazol-5-ylamino)-1,2,4,5-tetrazine-3-yl]-2,4-dihydro-3H-1,2,4-triazol-3-one. The reactions of nucleophilic substitution of symmetrically substituted tetrazine were shown to proceed more selectively. The resulting compounds were identified using 1 H, 13 CNMR spectroscopy, FTIR, LC-MS, and elemental analysis, as well as using X-ray diffraction analysis. The thermal stability of the new compounds was evaluated under isothermal and non-isothermal conditions and their energy characteristics were calculated. An unusual drop in stability was found on going from symmetrically substituted tetrazines to asymmetric ones.

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Nature of weak inter- and intramolecular interactions in crystals 4. Bifurcated N—H...N bond in a crystal of 3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine

Cited by 6 publications

References 18 publications

Nature of weak inter- and intramolecular interactions in crystals. 5. Interactions Na...H—B in a crystal of sodium salt of charge-compensated nido-carborane [9-SMe2-7,8-C2B9H10]−

Nature of weak inter- and intramolecular interactions in crystals. 5. Interactions Na...H—B in a crystal of sodium salt of charge-compensated nido-carborane [9-SMe2-7,8-C2B9H10]−

Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM)

Synthesis and Physicochemical Properties of Energetic 1,2,4,5‐Tetrazinyl Derivatives of 5‐Nitro‐2,4‐dihydro‐1,2,4‐triazol‐3‐one

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