Crystal and molecular structure of 1,6:8,13-propane-1,3-diylidene[14]-annulene

Gavezzotti, Angelo; Mugnoli, Angelo; Raimondi, Maria Valeria; Simonetta, M.

doi:10.1039/p29720000425

Cited by 12 publications

(39 citation statements)

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“…In the syn-bridged [14]annulene the C-C bonds have reduced alternancy, 1.365-1.418Å, [233] whereas alternate as single and double bonds, 1.34-1.46Å, in the 7-methoxycarbonyl derivative of 7 [234]. Both 8 and 9 have approximate bond equalized geometries, 1.38-1.41Å [235,236]. These structures have been calculated with different computational methods [237][238][239].…”

Section: Bridged [14]annulenesmentioning

confidence: 99%

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Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]-and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

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Section: Bridged [14]annulenesmentioning

confidence: 99%

“…The molecular structures of 6-9 have been determined by X-ray diffraction [233][234][235][236]. In the syn-bridged [14]annulene the C-C bonds have reduced alternancy, 1.365-1.418Å, [233] whereas alternate as single and double bonds, 1.34-1.46Å, in the 7-methoxycarbonyl derivative of 7 [234].…”

Section: Bridged [14]annulenesmentioning

confidence: 99%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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“…Table 2 shows the results of some calculations which have been performed on ideal crystals of various hydrocarbons, i.e. anthracene (ANT) at 290 K, adamantane (ADA) at 163 K, 1,6:8,13-(1,3-propanediylidene)annulene (PAN) at 298 K, and naphthalene (NAP) at 298 K. The unit-cell parameters and molecular models correspond to the experimental data (Mason, 1964;Lonsdale & Milledge, 1961;Nordman & Schmitkons, 1965;Gavezzotti, Mugnoli, Raimondi & Simonetta, 1972;Cruickshank, 1957). For simplicity, two essentially similar, but appreciably different conformations are considered in Table 2.…”

Section: Vibrational Effects Upon Molecular Coordinatesmentioning

confidence: 87%

Deriving the equilibrium conformation in molecular crystals by the quasi-harmonic procedure: some critical remarks

Filippini¹,

Gramaccioli²

1981

Acta Cryst Sect A

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Owing to progress in lattice-dynamical computing routines, free-energy calculations for perfect molecular crystals are no longer prohibitive in the quasi-harmonic approximation. Thus the consistent derivation of an equilibrium conformation at various temperatures and pressures, and even the stability range of various phases, may become a routine possibility, starting from semi-empirical potentials only. An example of such conformational calculations is given and discussed for the tetragonal phase of adamantane at 163 and 1 K. The effect of vibrational energy (even zero-point) and 0567-7394/81/030335-08501.00 entropy upon molecular orientation and position in the unit cell is shown not to be negligible by several examples. This precludes the possibility of calculating the cell parameters on free-energy grounds and the molecular coordinates by considering the minimum packing energy. For crystals with molecules fixed by symmetry, the quasi-harmonic approximation becomes particularly appropriate, since in this case for any unit cell the first derivatives of energy with respect to any molecular shift are zero. Some critical steps of such calculations are examined and discussed, especially in connection with converging processes. No particular problem is encountered in sampling the Brillouin zone, © 1981 International Union of Crystallography 336 EQUILIBRIUM CONFORMATION IN MOLECULAR CRYSTALS because only a limited number of points is necessary. Convergence of lattice sums to obtain packing energy is more critical, although for most practical purposes a maximum packing distance of 15 A is sufficient. The real difficulties of these calculations consist in the need of considering many degrees of freedom at once, and also in the inadequacy of present-day semi-empirical potentials.

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“…S18 for comparison (supplementary information †). The X-ray geometries of 14 27 and 15 28 are included for comparison with DFT-optimized geometries. Computed bond lengths in parent 14 and 15 are very close to each other and are on average longer than the X-ray derived bond lengths (see also earlier comments on this point).…”

Section: Protonation Oxidation and Reduction Of The Related Bridged [...mentioning

confidence: 99%

Theoretical (DFT, GIAO–NMR, NICS) study of carbocations (M+H)⁺, dications (M²⁺) and dianions (M²⁻) from dihydro-dicyclopenta[ef,kl]heptalene (dihydro-azupyrene), dihydro-dicyclohepta[ed,gh]pentalene, and related bridged [14]annulenes

Okazaki

Laali

2005

Org. Biomol. Chem.

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The annulenium ions of protonation, the two-electron oxidation dications, and the two-electron reduction dianions derived from dihydro- and dimethyldihydro derivatives (cis and trans) of dicyclopenta[ef,kl]heptalene (azupyrene) (1) and dicyclohepta[ed,gh]pentalene (2), which are the nonalternant isomers of pyrene, were studied by density functional theory (DFT) at the B3LYP/6-31G(d), 6-31+G(d,p), or 6-31++G(d,p) levels. Charge delocalization modes in the energetically most favored annulenium ions, as well as in the singlet and triplet dications and dianions, were assessed based on gauge-including atomic orbital (GIAO) Deltadelta](13)C values and via changes in natural population analysis (NPA) charges. Relative aromaticity/antiaromaticity in the annulenes were gauged via nucleus-independent chemical shift (NICS) and DeltaNICS. Annulenium ions of monoprotonation, the dications, and dianions derived from bismethano- and propanediylidene [14]annulenes were also studied by DFT for comparison with the cis-dihydro isomers derived from . Computed GIAO NMR data and the optimized geometries were compared with the experimental data when available, and the optimized geometries were compared with the X-ray data if known. A basis-set dependency study of the computed GIAO chemical shifts was also undertaken. The present DFT work represents the first detailed comparative theoretical study of charged annulenes derived from the dihydro derivatives of and .

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Crystal and molecular structure of 1,6:8,13-propane-1,3-diylidene[14]-annulene

Cited by 12 publications

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Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Deriving the equilibrium conformation in molecular crystals by the quasi-harmonic procedure: some critical remarks

Theoretical (DFT, GIAO–NMR, NICS) study of carbocations (M+H)⁺, dications (M²⁺) and dianions (M²⁻) from dihydro-dicyclopenta[ef,kl]heptalene (dihydro-azupyrene), dihydro-dicyclohepta[ed,gh]pentalene, and related bridged [14]annulenes

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Crystal and molecular structure of 1,6:8,13-propane-1,3-diylidene[14]-annulene

Cited by 12 publications

References 0 publications

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Deriving the equilibrium conformation in molecular crystals by the quasi-harmonic procedure: some critical remarks

Theoretical (DFT, GIAO–NMR, NICS) study of carbocations (M+H)+, dications (M2+) and dianions (M2−) from dihydro-dicyclopenta[ef,kl]heptalene (dihydro-azupyrene), dihydro-dicyclohepta[ed,gh]pentalene, and related bridged [14]annulenes

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Theoretical (DFT, GIAO–NMR, NICS) study of carbocations (M+H)⁺, dications (M²⁺) and dianions (M²⁻) from dihydro-dicyclopenta[ef,kl]heptalene (dihydro-azupyrene), dihydro-dicyclohepta[ed,gh]pentalene, and related bridged [14]annulenes