Crystal structure of triphenyl-7-cyclohepta-1,3,5-trienyltin, a fluxional organometallic molecule

Weidenborner, J. E.; Larrabee, R. B.; Bednowitz, A. L.

doi:10.1021/ja00767a014

Cited by 26 publications

(9 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, after an extensive study we were able to locate a "minimum-energy" geometry 7.64 kcal mol -1 higher in energy than 5, exhibiting a geometry that was close to the TS geometries of 2, 3, and 4 with respect to the planarity of the 7-membered ring. The computed low barriers for the ring flip support the fact that 1-5 are fluxional molecules (1)(2)(3), and that the equilibrium populations of the equatorial and axial conformations at ambient temperature are determined by ∆G. This validates our analysis based on using the equatorial and axial conformers; given the nature of the potential energy surfaces, only the equatorial and axial conformers and those very closely related to them are significantly populated at ambient temperature and contribute to the PE spectrum.…”

Section: Discussionsupporting

confidence: 78%

“…In the case of 7-methylcycloheptatriene (2), we found the equatorial conformational isomer to be lower in energy than the axial conformer. The preference of the axial conformation in a 7-substituted cycloheptatriene has previously been documented for triphenyl-7-cyclohepta-1,3,5-trienyltin, as evidenced by its crystal structure (2,3). Given our longstanding interest in studying conformational properties in the gas phase with ultraviolet (UV) photoelectron (PE) spectroscopy (4) and our work on identifying E,Z isomers of cyclohepta-2,4-dien-1-one (5) and N,N-dimethylcyclohepta-1,3,5-trien-1-amine (6), we initiated a computational and UV PE spectroscopic study of cycloheptatriene (1), 7-methylcycloheptatriene (2), 7-methoxycycloheptatriene (3), 7-methylthiocycloheptatriene (4), and 7-dimethylaminocycloheptatriene (5) (Fig.…”

Section: Introductionmentioning

confidence: 75%

See 1 more Smart Citation

UV photoelectron spectroscopic and computational study of 7-substituted cycloheptatrienes

Bajorek¹

2008

Can. J. Chem.

View full text Add to dashboard Cite

The He(I) photoelectron (PE) spectra of cycloheptatriene (1), 7-methylcycloheptatriene (2), 7-methoxycycloheptatriene (3), 7-methylthiocycloheptatriene (4), and 7-diemthylaminocycloheptatriene (5) were recorded and interpreted using MO energies and ionization potentials acquired from B3PW91 calculations. Partial simulated PE spectra were in good agreement with the experimental results. The axial and equatorial conformers have distinct PE spectra as illustrated by simulation. The PE spectra of 2, 3, and 5 are representative of the equatorial conformers, while the PE spectrum of 4 was in accord with a 1:1 mixture of equatorial and axial conformational isomers based on spectral simulation. The calculated free energy differences between the equatorial and axial conformers are in the order of 2 kcal mol -1 (1 cal = 4.184 J) for compounds 2, 3, and 5, where the equatorial conformational isomer is lowest in energy. In the case of 4, the equatorial conformer was only marginally lower in energy than its axial counterpart, where the free energy difference is 0.1 kcal mol -1 .Résumé : On a enregistré les spectres photoélectroniques (PE) He(I) du cycloheptatriène (1), du 7-méthyl-cycloheptatriène (2), du 7-méthoxycycloheptatriène (3) et du 7-méthylthiocycloheptatriène (4) et on les interprète en faisant appel aux énergies des orbitales moléculaires (OM) et des potentiels d'ionisation obtenus par des calculs B3PW91. Les spectres PE simulés partiels sont en bon accord avec les résultats expérimentaux. Tels qu'illustrés par la simulation, les conformères axiaux et équatoriaux présentent des spectres PE distincts. Les spectres PE des produits 2, 3 et 5 sont représentatifs de conformères équatoriaux alors que le spectre PE du composé 4 correspond au spectre de simulation d'un mélange 1:1 des isomères conformationnels équatoriaux et axiaux. Les différences d'énergie libre entre les conformères équatorial et axial sont de l'ordre de 2 kcal mol -1 pour les conformères équatoriaux des composés 2, 3 et 5. Dans le cas du produit 4, le conformère équatorial n'est que marginalement favorisé par une différence d'énergie de 0,1 kcal mol -1 par rapport au conformère axial.Mots-clés : cycloheptatriènes substitués en position 7, spectroscopie photoélectronique He(I), B3PW91, simulation spectrale.[Traduit par la Rédaction] Bajorek and Werstiuk 450

show abstract

Section: Discussionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 75%

UV photoelectron spectroscopic and computational study of 7-substituted cycloheptatrienes

Bajorek¹

2008

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…Of such Z 1 -bound cycloheptatrienyl complexes only three examples in transition metal chemistry and some more involving tin have been crystallographically characterised so far. [23][24][25][26][27][28][29][30] A Z 1 -cycloheptatrienyl complex has also been proposed as a short-lived intermediate in the reaction of CHT complexes with nucleophiles. 20 In agreement with previous reports, the seven-membered ring adopts a distinct boat-conformation as required by the tetrahedral environment of the alkyl-bound carbons C1 and C23, which feature bond lengths of Pd1-C1 = 2.023(7) Å, C1-C2 = 1.482(15) Å, C1-C7 = 1.496(12) Å, Pd2-C23 = 2.008(9) Å, C23-C24 = 1.500 (14) Å and C23-C29 = 1.489(12) Å.…”

mentioning

confidence: 99%

A hybrid carbocyclic/N-heterocyclic carbene ligand

Jandl

Pöthig

2017

Chem. Commun.

View full text Add to dashboard Cite

We report the synthesis and characterisation of the first complex bearing a bidentate carbocyclic/N-heterocyclic carbene ligand, which represents an unprecedented combination of these two carbene classes. Starting from an unsubstituted cycloheptatrienylidene-Pd complex, the ligand was built up in an on-site synthesis at the metal center. DFT calculations were employed to understand the crucial allyl-to-alkyl rearrangement of the carbocycle in this sequence and all its binding modes during the reaction cascade were crystallographically characterised.

show abstract

“…According to an electron diffraction (ED) and a microwave (MW) investigation of CHT [4,51, the molecule is nonplanar and possesses a boat form. This has been confirmed by X-ray studies of the substituted CHTs [6][7][8][9] and AZPs [lo-121 shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 62%

Theoretical determination of molecular structure and conformation

Cremer

Dick

Christeu

1984

Journal of Molecular Structure: THEOCHEM

View full text Add to dashboard Cite

Restricted Hartree-Fock calculations have been carried out for 1,3,&cycloheptatriene, norcaradiene, lH-azepine, benzenimine (azanorcardiene), oxepine and benzene oxide (oxanorcaradiene) employing the STO-3G, 4-31G and 6-31G* basis sets. Theoretical geometries, conformations and barriers to ring inversion have been obtained and compared with the available experimental structural data. It has been found that the cyclotrienes possess a boat conformation with a constant admixture of 22% chair character leading to a flattening of the triene part and n-electron delocalization typical for a planar polyene. The structural data obtained in this work suggest that cyclic delocalization of either 6~ (homoaromaticity) or 8~ electrons (antiaromaticity) is not present in the three cyclotrienes. The former possibility, however, cannot be excluded in the case of the three norcaradienes. 5 .6 :, X7 p" (c D 2 X=CHz X 4 X=NH 6 X=0 2 ' CHT may obtain some aromatic character by 1,6 overlap of 2pn-orbitals and a homoconjugative closure of the triene part. In NCD, however, interactions between the n-molecular orbit& (n-MOs) of the diene part and the

show abstract

Crystal structure of triphenyl-7-cyclohepta-1,3,5-trienyltin, a fluxional organometallic molecule

Cited by 26 publications

References 2 publications

UV photoelectron spectroscopic and computational study of 7-substituted cycloheptatrienes

UV photoelectron spectroscopic and computational study of 7-substituted cycloheptatrienes

A hybrid carbocyclic/N-heterocyclic carbene ligand

Theoretical determination of molecular structure and conformation

Contact Info

Product

Resources

About