Cyclooctatetraene in metal complexes—planar does not mean aromatic

Dominikowska, Justyna; Palusiak, Marcin

doi:10.1039/c0nj00060d

Cited by 19 publications

(21 citation statements)

References 50 publications

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“…Interestingly, HOMA for tub-like structures is negative, similarly as for antiaromatic species, and it is close to that obtained for the free neutral COT ring. 3,28 This additionally supports the earlier conclusion according to which in these cases, we have a situation when the neutral COT ring interacts with free electrons located in its surroundings. The symmetry of starting geometries used in optimization procedure is given in square brackets.Values of average CC bond lengths, R av , are in angstroms.…”

Section: Resultssupporting

confidence: 89%

“…To estimate the degree of nonplanarity of the COT ring, we use the DTor parameter defined and successfully applied in our earlier studies on COT in transition metal complexes. 28 The DTor parameter can be expressed as follows:…”

Section: Methodsmentioning

confidence: 99%

“…As the reference data, we use the value from the B3LYP/6-31111G(d,p) optimized structure of COT ( P ju ref j 5 215.928, see SI data accompanying the ref. 28 for atomic coordinates) The closer to 0 is DTor parameter, the flatter is the ring in question.…”

Section: Methodsmentioning

confidence: 99%

“…Secondly, very recently, we have reported that although COT in metal complexes may adopt a planar conformation, the main factor affecting its structure in such complexes is the efficiency of the metal-COT interaction (i.e., complexation). 28 The aromatization, in such cases usually considered as the effect of leading importance, in fact seems to be rather a background effect.…”

Section: Introductionmentioning

confidence: 99%

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Cyclooctatetraene dianion—an artifact?

Dominikowska

Palusiak

2011

J Comput Chem

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Cyclooctatetraene in its dianionic form (COT(2-)) is considered to be partially or fully aromatic due to the fact that, unlike its neutral counterpart, it adopts planar structure with CC bonds equalized. However, some authors report that this dianion is neither planar nor aromatic. Thus, we performed a detailed analysis of the COT(2-) case. The influence of several technical parameters on the result of calculations on COT(2-) was investigated. It appears from our analysis that the use of some specific level of approximation may lead to very misleading results in which the COT ring occurs in its neutral structure, in fact being neither planar nor aromatic. Additionally, our results may suggest that COT(2-) dianion is rather an artificial structure (being the result of specific basis set description) and should not occur in experimental conditions.

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Section: Resultssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cyclooctatetraene dianion—an artifact?

Dominikowska

Palusiak

2011

J Comput Chem

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“…It was also demonstrated that the strength of the given chemical bond is related to the amount of electron density in BCP (q BCP ). This observation was made for both shared bonds [45][46][47][48][49][50] and the bonds of closed-shell character [51][52][53][54][55] (Note that some exceptions were also reported [56][57][58]). There are also other parameters of electron density function in BCP, which may give valuable information on the bonding, such as the laplacian of electron density, r 2 qBCP, and its components being the eigenvalues of hessian in BCP 2 .…”

Section: Resultsmentioning

confidence: 96%

EL: the new aromaticity measure based on one-electron density function

Dominikowska

Palusiak

2012

Struct Chem

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Ellipticity of the bond, being the quantity which numerically reflects how far the given chemical bond has elliptic cross-section, may be used to estimate p-electron contribution in bonding. We make use of that fact and develop a new measure of aromaticity-EL index. Since ellipticity is available from calculations on oneelectron density function, EL can be used for both theoretical and experimental data. The EL measure is normalized to make interpretation of this parameter as easy and comfortable as possible. We compare EL values with the values of other commonly used aromaticity measures, such as HOMA, PDI, FLU, and NICS. It appears that the indications of EL are in agreement with indications of other indices and general expectations.

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