Molecular Structure of Methylcyclopropane and trans-1,2-Dimethylcyclopropane as Studied by Gas Electron Diffraction.

Klein, Asne; Schrumpf, G.; Seip, Ragnhild; Weidlein, Johann; Spahiu, Kastriot

doi:10.3891/acta.chem.scand.35a-0425

Cited by 22 publications

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“…For methylcyclopropane and trans-l,2-dimethylcyclopropane in the vapour phase, we found 118.3 and 118.4 °, respectively, for the CCC bond angles involving the methyl carbon atoms (Klein & Schrumpf, 1981). This is about midway between the corresponding CCC bond angles found in the title molecule.…”

Section: • 0{1)mentioning

confidence: 50%

“…Cyclopropanecarboxylic acid melts at 292 K. In the literature, the structure of trans,trans-2,3-dimethylcyclopropanecarboxylic acid has been reported (Luhan & McPhail, 1972). Since methyl groups do not significantly affect the cyclopropane geometry (Klein & Schrumpf, 1981), the geometry of this molecule might be considered to be close to the hitherto unknown structure of the unsubstituted acid. However, in the crystal, the dimethyl-substituted acid deviates from the anticipated molecular C~ symmetry.…”

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confidence: 99%

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Substituted cyclopropanes. 8. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid

Jones¹,

Schrumpf²

1987

Acta Crystallogr C

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Abstract. C8H1402, Mr= 142.20, monoclinic, P21/n, a--6.3457 (10), b= 11.7207 (14), c= 11.758 (2)A, t= 104.27 (2) °, V= 847.5 A 3, z= 4, Dx= 1.11Mgm -3, 2(MoKa)=0.71069A, /t(MoKa)= 0.05 mm -1, F(000) = 312, T= 293 K, R = 0.059 for 1313 unique observed reflections. The molecule adopts a slightl3/distorted cis-bisected conformation, with the carbonyl oxygen eclipsing the ring. The eyclopropane ring i~ asymmetric, with one short and two longer bonds, in accordance with theoretical expectations. The absolute values of the bond lengths and several bond angles indicate substantial steric interactions between the carboxyl and the two cis methyl groups. The molecules are linked in pairs across centres of symmetry by the usual carboxyiic acid hydrogen bonding.

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Section: • 0{1)mentioning

confidence: 50%

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confidence: 99%

Substituted cyclopropanes. 8. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid

Jones¹,

Schrumpf²

1987

Acta Crystallogr C

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“…The cyclopropyl C atoms have bonding distances and angles which suggest, within experimental error, that the atoms form an equilateral triangle, but the bonding distances, which range from 1.452 (5) to 1.497 (4)A, are again significantly shorter than the sp3-sp 3 value of 1.54 ]~ quoted above, and in fact are considerably shorter than the distance of 1.510/~ observed for free cyclopropane (Streitweiser & Heathcock, 1981) and the 1.509 (1)A observed for methylcyclopropane (Klein & Schrumpf, 1981).…”

Section: Introduction a Recently Developed And Important Classmentioning

confidence: 63%

“…The effect of increased C p orbital contribution to the C-C bonding (Streitweiser & Heathcock, 1981) may be seen by considering the C-C bond distances of the cyclopropyl fragment. The average C(alkylidyne)-C(cyclopropyl) bonding distance is 1.465 (4)A, significantly shorter than the average spa-sp 3 C-C bond length of 1.54A (International Tables for X- ray Crystallography, 1968) and shorter even than the analogous bond in methylcyclopropane, observed to be 1.517(2)/~ (Klein & Schrumpf, 1981), and the analogous bond in (fla-CHaC)Co3(CO)9, reported as 1.53 (3) A (Sutton & Dahl, 1967). In fact, this distance approximates the sp-sp 3 C-C bond length of 1.460 (3) A observed for propyne, CHaC_--CH (International Tables for X-ray Crystallography, 1968).…”

Section: Introduction a Recently Developed And Important Classmentioning

confidence: 80%

1,1,1,2,2,2,3,3,3-Nonacarbonyl-μ3-cyclopropylmethylidyne-triangulo-tricobalt, (μ3-c-C3H5C)Co3(CO)9

Seidler¹,

McKenna²,

Kulzick³

et al. 1985

Acta Crystallogr C

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“… a Gas electron diffraction data taken from ref , the C−C bonds in the cyclopropyl group are assumed equal. b Taken from ref .…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Ab Initio and Cryospectroscopic Investigation of the Van der Waals Complexes of Methylcyclopropane with Hydrogen Chloride and Boron Trifluoride

Everaert¹,

Herrebout²,

Veken³

2001

J. Phys. Chem. A

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The mid infrared spectra of methylcyclopropane-HCl and methylcyclopropane-BF 3 mixtures, dissolved in liquid argon (LAr) or liquid nitrogen (LN 2 ), have been examined. In LAr solutions, evidence was found for the formation of two different isomers of the 1:1 van der Waals complexessan asymmetric complex, in which the electron acceptor interacts with the C-C bond adjacent to the methyl group, and a symmetric complex in which the interaction occurs with the opposite C-C bond. At higher concentrations, indications were found for the formation of a chain-type 1:2 complex. In LN 2 solutions, only the two 1:1 isomers of the HCl complex have been observed. Using spectra recorded at different temperatures, the complexation enthalpy ∆H°in LAr was determined to be -9.5(4) and -8.3(3) kJ mol -1 for the symmetric and asymmetric MCP‚ HCl complexes, and -9.1(2) and -6.7(5) kJ mol -1 for the symmetric and asymmetric MCP‚BF 3 complexes, respectively. In addition, for all investigated species, full MP2/6-31+G(d,p) geometry optimizations and B3LYP/6-311++G(d,p) frequency calculations were performed, and the complexation energies were calculated at the MP2/6-311++G(3df,2pd) level. These calculations indicate that the isomers of the MCP‚HCl complex are of comparable strength, while the asymmetric MCP‚BF 3 complex is significantly less stable than its symmetric counterpart. Using Free Energy Perturbation Monte Carlo simulations to calculate the solvent influences, and using statistical thermodynamics to account for zero-point vibrational and thermal contributions, from the experimental complexation enthalpies, the complexation energies are estimated to be -15.7(8) and -16.0(9) kJ mol -1 for the symmetric and asymmetric MCP‚HCl complexes, which is in agreement with the ab initio results, and -14.0(8) and -15.3(5) kJ mol -1 for the corresponding MCP‚BF 3 species.

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Molecular Structure of Methylcyclopropane and trans-1,2-Dimethylcyclopropane as Studied by Gas Electron Diffraction.

Cited by 22 publications

References 0 publications

Substituted cyclopropanes. 8. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid

Substituted cyclopropanes. 8. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid

1,1,1,2,2,2,3,3,3-Nonacarbonyl-μ3-cyclopropylmethylidyne-triangulo-tricobalt, (μ3-c-C3H5C)Co3(CO)9

Ab Initio and Cryospectroscopic Investigation of the Van der Waals Complexes of Methylcyclopropane with Hydrogen Chloride and Boron Trifluoride

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