Systematic effects of crystal-packing forces: biphenyl fragments with hydrogen atoms in all four ortho positions

Brock, Carolyn Pratt; Minton, Robin P.

doi:10.1021/ja00195a010

Cited by 150 publications

(120 citation statements)

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“…In the Cambridge Structural Database 48 we found 10 4-alkyl-DMA derivatives, in which the C 1 -N bond lengths varied between 1.36 and 1.40 Å. Pyramidalization was in most cases significantly smaller than in the gas phase, and the dimethylamino group was twisted only slightly with respect to the plane of the benzene ring. Effects of crystal-packing forces on dihedral angles are common, 49 but in this case the low inversion barrier 47 also allows flattening of the amino group due to intermolecular interactions in the solid state. The HF/6-31G* level is known to be generally adequate for the calculation of the structures of organic molecules.…”

Section: Computed Molecular Structures Wave Functions and Potentialmentioning

confidence: 99%

Vibrational Spectra of N,N-Dimethylaniline and Its Radical Cation. An Interpretation Based on Quantum Chemical Calculations

1996

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The resonance Raman spectrum of the radical cation of N,N-dimethylaniline (DMA) has been remeasured, and different types of ab initio calculations have been performed to interpret the vibrational spectra of this species and the deuteriated isotopomers previously studied by Poizat et al. (J. Chem. Phys. 1989, 90, 4697). Density functional methods (UBLYP/6-31G*) give results superior to those of Hartree-Fock calculations for the vibrational frequencies of the radical cation of DMA. The same level of theory was also successfully applied to the vibrational spectrum of aniline. CASSCF calculations were used to study the potential energy surfaces of the lowest excited states of the radical cation of DMA, allowing the estimation of resonance Raman intensities. For the neutral DMA conventional HF/6-31G* calculations allow a straightforward interpretation of the infrared and Raman spectra. The calculations lead to revision of some of the previous empirical assignments.

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Section: Computed Molecular Structures Wave Functions and Potentialmentioning

confidence: 99%

Vibrational Spectra of N,N-Dimethylaniline and Its Radical Cation. An Interpretation Based on Quantum Chemical Calculations

1996

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“…Biphenyl and its derivatives have been studied extensively in the past because of the differences found in the inter-ring torsion angle ~p in the solid state (Charbonneau & Delugeard, 1976, 1977Brock, Blackburn & Haller, 1984;Brock & Hailer, 1984a,b;Samdal, 1985;Brock & Minton, 1989) and in the gas phase (Almenningen & Bastiansen, 1958;Bastiansen & Traetteberg, 1962). These systems have also been investigated for those structures which pose difficulties in refinement because of a low observed-data-to-parameter ratio (a result of the crystals being non-centrosymmetric, having large overall displacement parameters and growing as thin needles or plates) (Brock, Blackburn & Hailer, 1984).…”

Section: Commentmentioning

confidence: 99%

Biphenyl-2-methanol

Rajnikant¹,

Watkin²,

Tranter³

1995

Acta Crystallogr C

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“…The rotational dynamics around the linkage bond have been well studied both experimentally and theoretically. [24][25][26][27][28][29][30][31][32][33] The parameters that characterize methyl group rotation and other similar motions can be studied in bulk samples using solid state NMR relaxation techniques [23] and interpreted in terms of small intermolecular perturbations to parameters determined from intramolecular interactions alone by electronic structure calculations. [34] Using electronic structure calculations and the X-ray data together, we show that even though there is a change in conformation for 4,4'-dimethoxybiphenyl in going from the isolated molecule to the crystalline state, this change involves only the relative orientation of the two benzene rings (Figure 1) and the "half molecule" (or 4-methoxyphenyl group), has almost the same conformation in the crystal as it has in the isolated molecule.…”

Section: Introductionmentioning

confidence: 99%

Single‐Crystal X‐Ray Diffraction, Isolated‐Molecule and Cluster Electronic Structure Calculations, and Scanning Electron Microscopy in an Organic solid: Models for Intramolecular Motion in 4,4′‐Dimethoxybiphenyl

Wang

Rotkina

et al. 2012

ChemPhysChem

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Single-crystal X-ray diffraction, isolated-molecule and cluster electronic structure calculations, and scanning electron microscopy in an organic solid: Models for intramolecular motion in 4,4'-dimethoxybiphenyl http://onlinelibrary.wiley.com/doi/10.1002/cphc.201101067/abstract Xianlong Wang, *[a] Lolita Rotkina, [b] Hong Su, [c] and Peter A. Beckmann, Mawr, Pennsylvania 19010-2899, USA Fax: (+1) 610-526-7489 E-mail: pbeckman@brynmawr.edu Accepted for publication in ChemPhysChem February 2012This paper brings together field emission scanning electron microscopy, single-crystal Xray diffraction, and ab initio electronic structure calculations in both an isolated molecule and a cluster of 7 whole and 14 half molecules of 4,4'-dimethoxybiphenyl to investigate coupled methyl group rotation (over a barrier) and methoxy group libration (meaning a rotation from the ground state not all the way to the transition state and back again). The structure of the isolated molecule, determined by the electronic structure calculations, is compared with the structure of the molecule found in the crystal. As the methyl group rotates from its ground state to its transition state, the methoxy group rotates 30 O in the isolated molecule and 16 O in the cluster. The calculated barriers for this coupled methyl group rotation and methoxy group libration in the isolated molecule and in the crystal are 12.8 kJ mol -1 and 10.3 kJ mol -1 respectively, suggesting that intermolecular interactions in the crystal lower the barrier. These barriers are compared with the value of 11.5 ± 0.5 kJ mol -1 obtained from solid state 1 H spin-lattice relaxation measurements [P. A. Beckmann and E. Schneider, J. Chem. Phys. 2012, 136, 054508, 1-9.] Wang et al 2 IntroductionSmall methyl-substituted organic molecules in the solid state are good systems for investigating (1) the relationship between methyl group rotation and molecular and crystal structure [1][2][3][4][5][6][7][8][9][10][11][12] and (2) for developing models for intramolecular motion. [7,11,[13][14][15][16] They are also good test cases for comparing calculated and measured barriers to intramolecular motion. [17][18][19][20][21][22] In this paper we bring together single crystal X-ray crystallography, isolated molecule and molecular cluster ab initio electronic structure calculations, and field emission scanning electron microscopy with 4,4'-dimethoxybiphenyl (Figures 1 and 2). This allows us to relate the properties describing methyl group rotation and methoxy group libration to the structure on both the microscopic and macroscopic scales. By "methyl group rotation", we mean a rotation from a ground state to a transition state followed by a return to the ground state either by rotating in the same direction or by rotating in the opposite direction. By "methoxy group libration", we mean a rotation from the ground state only part way to the transition state followed by a reversal of the rotation back to the ground state. We compare the calculated barrier for this coupled met...

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Systematic effects of crystal-packing forces: biphenyl fragments with hydrogen atoms in all four ortho positions

Cited by 150 publications

References 4 publications

Vibrational Spectra of N,N-Dimethylaniline and Its Radical Cation. An Interpretation Based on Quantum Chemical Calculations

Vibrational Spectra of N,N-Dimethylaniline and Its Radical Cation. An Interpretation Based on Quantum Chemical Calculations

Biphenyl-2-methanol

Single‐Crystal X‐Ray Diffraction, Isolated‐Molecule and Cluster Electronic Structure Calculations, and Scanning Electron Microscopy in an Organic solid: Models for Intramolecular Motion in 4,4′‐Dimethoxybiphenyl

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