Conformational analysis—CI

Wertz, David H.; Allinger, Norman L.

doi:10.1016/s0040-4020(01)90680-5

Cited by 375 publications

(27 citation statements)

References 31 publications

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“…The direction of rotation, as seen in Figure 2, presumably is a result of minimizing steric interactions since the a carbon, CP(6), is rotated away from the CF3 group positioned at C(3). The closest contact between the phenyl group and a fluorine atom is 3.123 (7) 8, for CP(6)-F (31). The closest contact between the phenyl group and a fluorine atom is 3.123 (7) 8, for CP(6)-F (31).…”

Section: Resultsmentioning

confidence: 98%

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Pentacoordinated molecules. 31. Sterically oriented structures of perfluoromethyl-substituted spirophosphoranes centered between the trigonal bipyramid and the rectangular pyramid

Brown¹,

Day²,

Husebye³

et al. 1978

Inorg. Chem.

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The crystal and molecular structures of 2,2,3,3-tetrakis(trifluoromethyl)-5-tert-buty~-7,8-benzo-l,4,6,9-tetraoxa-5h5phosphaspiro[4.4]nonene, (C6H402)(02C2(CF3)4)PC(CH3)3, and 2,2,3,3-tetrakis(trifluoromethyl)-5-phenyl-7,8-benzo-1 ,4,6,9-tetraoxa-5h5-phosphaspiro[4.4]nonene, (C6H402)(0:C2(CF~)4)Pc6H5, have been determined by single-crystal X-ray diffraction analysis. The tertiary butyl derivative crystallizes in the monoclinic system (space group P2,/n) with cell constants a = 12.285 (4) A, b = 11.766 (5) A, c = 14.1 16 (3) A, fl = 90.93 (3)', and Z = 4. The structure was refined by full-matrix least squares to a final R value of 0.088 and a weighted R value of 0.086 for 3220 independent reflections with F 1 @). The molecular geometry is displaced 37% along the Berry intramolecular exchange coordinate. Pertinent features of the molecule relative to a rectangular pyramid are the diagonal 0-P-0 angles of 131.4 (2) and 164.3 (2)' and the four bond angles between the apical P-C bond of the tert-butyl group and the P-0 bonds, 118.9 (3), 98.0 (2), 109.7 (7), and 97.5 (3)'. The differences in the P-0 bond lengths, 1.709 (4) vs. 1.648 (4) 8, for the perfluoropinacol residue and 1.684 (4) vs. 1.61 8 (4) 8, for the benzo residue, are indicative of the trigonal-bipyramidal character. The phenyl derivative crystallizes in the monoclinic space group C2/c with cell constants a = 18,108 (8) A, b = 16.826 (7) A, c = 14.593 (3) A, and fl = 112.71 (2)'. The structure was refined by full-matrix least squares to a final R value of 0.076 and a weighted R value of 0.062 for 2499 independent reflections with F L 3u(F). The molecular geometry is displaced 52% along the Berry intramolecular exchange coordinate. For this derivative, the diagonal 0-P-0 angles are 136.8 (2) and 161.3 (2)' and the four bond angles between the apical P-C bond of the phenyl group and the P-0 bonds are 114.9 (2), 98.2 (2), 108.2 (2), and 100.5 ( 2 ) ' . The differences in the P-0 bond lengths, 1.685 (3) vs. 1.665 (3) 8, for the perfluoropinacol groups and 1.668 ( 3 ) vs. 1.614 (3) for the benzo residue, again are indicative of trigonal-bipyramidal character. Conformational minimization shows that intermolecular effects are important in accounting for the smaller displacement along the Berry coordinate for the more sterically hindered tert-butyl derivative.

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Section: Resultsmentioning

confidence: 98%

“…The closest contact between a methyl carbon of the tert-butyl group and a fluorine atom is 3.22 (1) 8, for CP(2)-F (31). The nearly planar phenyl group, plane IX of Table IX, exhibits a dihedral angle of 17.1' (Table X) with the axial P-O(2)-O(4)-CP( 1) direction (plane IV).…”

Section: Resultsmentioning

confidence: 99%

Pentacoordinated molecules. 31. Sterically oriented structures of perfluoromethyl-substituted spirophosphoranes centered between the trigonal bipyramid and the rectangular pyramid

Brown¹,

Day²,

Husebye³

et al. 1978

Inorg. Chem.

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“…However, both high-level computational and experimental studies have indicated that these conformers are essentially isoenergetic. [17][18][19][20][21] This is presumably because steric repulsion by the methyl groups in the anti conformer destabilizes this structure. Dihedral angle drive calculations employing a number of different force fields implemented in the Maestro/Macromodel molecular mechanics package [22] indicate that all are able to reproduce this behavior both in the gas phase and when continuum solvation terms (GB/ SA water or chloroform) [23] are included in the calculation (data not shown).…”

Section: Introductionmentioning

confidence: 99%

Conformational and Structural Analysis of a ter‐Cyclopentane Scaffold for Molecular Recognition

et al. 2006

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Well-defined oligomers of cycloalkanes comprise a relatively unstudied class of organic compounds, and may have general utility in the development of receptors for biologically relevant molecules. We have investigated the solution structure of a ter-cyclopentane member of this class by molecular modeling and by NMR spectroscopy. We find that the molecular ensembles derived from conformational searches incorporating NMR-derived restraints are in excellent qualitative agreement with unrestrained molecular mechanics conformation searches. The ter-cyclopentane scaffold adopts an ex-

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“…Many ideas and theories have been advanced to account for the interesting stereochemical control exhibited in these reactions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). In contrast, however, much less attention has been paid to the matter of quantitatively predicting these stereochemical product ratios, with only two approaches, those of Wigfield (1 1) and of Wipke and Gund (12), having been presented in the literature.…”

Section: Introductionmentioning

confidence: 99%

Quantitative prediction of stereochemistry in the reduction of cyclohexanones by sodium borohydride

Murugan¹

1980

Can. J. Chem.

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Conformational analysis—CI

Cited by 375 publications

References 31 publications

Pentacoordinated molecules. 31. Sterically oriented structures of perfluoromethyl-substituted spirophosphoranes centered between the trigonal bipyramid and the rectangular pyramid

Pentacoordinated molecules. 31. Sterically oriented structures of perfluoromethyl-substituted spirophosphoranes centered between the trigonal bipyramid and the rectangular pyramid

Conformational and Structural Analysis of a ter‐Cyclopentane Scaffold for Molecular Recognition

Quantitative prediction of stereochemistry in the reduction of cyclohexanones by sodium borohydride

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