Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. I. Single-crystal X-ray structure determinations of two modifications of ethane

Nes, G. J. H. van; Vos, A.

doi:10.1107/s0567740878007037

Cited by 110 publications

(43 citation statements)

References 6 publications

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“…The structural chemistry of the β‐B‐agostic amidoboranes mirrors that of β‐agostic alkyls: the CαCβ bond length in [(MeCp) 2 Zr(Et)(PMe 3 )] + is 1.47(2) Å versus 1.532(2) Å for the CC bond in ethane 31. 32…”

Section: Resultsmentioning

confidence: 95%

Synthesis and Structure of Amido‐ and Imido(pentafluorophenyl)borane Zirconocene and Hafnocene Complexes: NH and BH Activation

Jacobs

Fuller

Coles

et al. 2012

Chemistry A European J

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Treatment of Me(2)S·B(C(6)F(5))(n) H(3-n) (n=1 or 2) with ammonia yields the corresponding adducts. H(3)N·B(C(6)F(5))H(2) dimerises in the solid state through N-H···H-B dihydrogen interactions. The adducts can be deprotonated to give lithium amidoboranes Li[NH(2)B(C(6)F(5))(n)H(3-n)]. Reaction of the n=2 reagent with [Cp(2)ZrCl(2)] leads to disubstitution, but [Cp(2)Zr{NH(2)B(C(6)F(5))(2)H}(2)] is in equilibrium with the product of β-hydride elimination [Cp(2)Zr(H){NH(2)B(C(6)F(5))(2)H}], which proves to be the major isolated solid. The analogous reaction with [Cp(2)HfCl(2)] gives a mixture of [Cp(2)Hf{NH(2)B(C(6)F(5))(2)H}(2)] and the N-H activation product [Cp(2)Hf{NHB(C(6)F(5 )(2)H}]. [Cp(2)Zr{NH(2)B(C(6)F(5))(2)H}(2)]·PhMe and [Cp(2)Hf{NH(2)B(C(6)F(5))(2)H}(2)]·4(thf) exhibit β-B-agostic chelate bonding of one of the two amidoborane ligands in the solid state. The agostic hydride is invariably coordinated to the outside of the metallocene wedge. Exceptionally, [Cp(2)Hf{NH(2)B(C(6)F(5))(2)H}(2)]⋅PhMe has a structure in which the two amidoborane ligands adopt an intermediate coordination mode, in which neither is definitively agostic. [Cp(2)Hf{NHB(C(6)F(5))(2)H}] has a formally dianionic imidoborane ligand chelating through an agostic interaction, but the bond-length distribution suggests a contribution from a zwitterionic amidoborane resonance structure. Treatment of the zwitterions [Cp(2)MMe(μ-Me)B(C(6)F(5))(3)] (M=Zr, Hf) with Li[NH(2)B(C(6)F(5))(n)H(3-n)] (n=2) results in [Cp(2) MMe{NH(2)B(C(6)F(5))(2)H}] complexes, for which the spectroscopic data, particularly (1)J(B,H), again suggest β-B-agostic interactions. The reactions proceed similarly for the structurally encumbered [Cp''(2)ZrMe(μ-Me)B(C(6)F(5))(3)] precursor (Cp''=1,3-C(5)H(3)(SiMe(3))(2) , n=1 or 2) to give [Cp''(2)ZrMe{NH(2)B(C(6)F(5))(n)H(3-n)}], both of which have been structurally characterised and show chelating, agostic amidoborane coordination. In contrast, the analogous hafnium chemistry leads to the recovery of [Cp''(2)HfMe(2)] and the formation of Li[HB(C(6)F(5))(3)] through hydride abstraction.

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Section: Resultsmentioning

confidence: 95%

Synthesis and Structure of Amido‐ and Imido(pentafluorophenyl)borane Zirconocene and Hafnocene Complexes: NH and BH Activation

Jacobs

Fuller

Coles

et al. 2012

Chemistry A European J

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“…Since the ED of the promolecule is calculated as a static function as well, the consequences of thermal smearing are to a great extent rejected for derivatives of p. The approach described was used for the first time in the study of monoclinic modification of ethane, C2H6 (55). This compound crystallizes at 90 K and only a small temperature gap exists between the melting point and X-ray measurement temperature of 85 K (56). Therefore the thermal smearing significantly distorts the ED curvature.…”

Section: Combination Of the Fourier And Position Space Presentationsmentioning

confidence: 99%

Topological analysis of the experimental electron density

Tsirelson¹

1996

Can. J. Chem.

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“…18,19 Of course, the structure corresponding to the absolute potential energy minimum for the force field employed (i.e., the crystal structure of the model) does not necessarily agree with the crystal structure found in nature. Nevertheless, the experimental crystal data from single-crystal x-ray structure determinations of ethane 18 and n-pentane 19 was used here as a starting point to find a reasonable guess for the crystal structure of the model, in order to compare the equations of state of crystalline and amorphous inherent structures. Initially, united-atom model systems were generated using the experimental carbon atom positions as sites for the CH 2 and CH 3 pseudo atoms (Fig.…”

Section: B Comparison To Crystalsmentioning

confidence: 99%

Isotropic tensile strength of molecular glasses

Utz

Debenedetti

Stillinger

2001

The Journal of Chemical Physics

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The relationship between the bulk density and pressure of configurations corresponding to local minima on the potential energy surface of molecular models of ethane, n-pentane and cyclopentane (the equation of state of their energy landscape) has been explored. Like simpler, atomic fluids, these systems exhibit a limiting bulk density below which minimum energy configurations are no longer spatially homogeneous, but consist instead of a locally dense fraction and large, system-spanning voids. In the case of n-pentane, the sampling of the minima on the energy landscape was found to depend strongly on temperature, due to changing Boltzmann factors associated with the different conformers in the liquid. The pressures of the minimum energy configurations, in contrast, were found to be essentially independent of the liquid temperature in all cases. The highest amount of isotropic tension (negative pressure) that minimum energy configurations can sustain is reached at the limiting densities, and is of similar magnitude (approx. 250 MPa) for all three model substances. Crystalline configurations of ethane and n-pentane, in contrast, were found to exhibit higher isotropic tensile strength than their amorphous counterparts. A pro-1 nounced segregation of end groups on the boundary of large voids was observed in the minimum energy configurations of low bulk density pentane. This observation could have implications for homogeneous bubble nucleation in linear alkanes.

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Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. I. Single-crystal X-ray structure determinations of two modifications of ethane

Cited by 110 publications

References 6 publications

Synthesis and Structure of Amido‐ and Imido(pentafluorophenyl)borane Zirconocene and Hafnocene Complexes: NH and BH Activation

Synthesis and Structure of Amido‐ and Imido(pentafluorophenyl)borane Zirconocene and Hafnocene Complexes: NH and BH Activation

Topological analysis of the experimental electron density

Isotropic tensile strength of molecular glasses

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