On the performance of some aromaticity indices: A critical assessment using a test set

Feixas, Ferran; Matito, Eduard; Poater, Jordi; Solà, Miquel

doi:10.1002/jcc.20914

Cited by 272 publications

(284 citation statements)

References 147 publications

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“…50,126 On the other hand, it does a good job in polycyclic aromatic hydrocarbons. 127 Ángyán 128, 129 showed the connection between the 2c-ESI and the LRK for the QTAIM partition, which suggests that the PLR and the PDI could be measuring the same effect in a molecular ring.…”

Section: Flumentioning

confidence: 99%

Quantifying aromaticity with electron delocalisation measures

et al. 2015

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Aromaticity cannot be measured directly by any physical or chemical experiment because it is not a well-defined magnitude. Its quantification is done indirectly from the measure of different properties that are usually found in aromatic compounds such as bond length equalisation, energetic stabilisation, and particular magnetic behaviour associated with induced ring currents. These properties have been used to set up the myriad of structural-, energetic-and magnetic-based indices of aromaticity known to date. Cyclic delocalisation of mobile electrons in two or three dimensions is probably one of the key aspects that characterise aromatic compounds. However, it has not been until the last decade that electron delocalisation measures have been widely employed to quantify aromaticity. Some of these new indicators of aromaticity such as the PDI, FLU, ING, and INB were defined in our group. In this paper, we review the different existent descriptors of aromaticity that are based on electron delocalisation properties, we compare their performance with indices based on other properties, and we summarise a number of applications of electronic-based indices for the analysis of aromaticity in interesting chemical problems.2

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Section: Flumentioning

confidence: 99%

Quantifying aromaticity with electron delocalisation measures

et al. 2015

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“…NICS π values can be calculated through the decomposition of NICS indices into their canonical molecular orbital (CMO) components [69] using the NBO 5.0 program [70,71]. NICS(1) zz and NICS(0) πzz were reported to be the best measures of aromaticity among the different NICS-related definitions in organic molecules [66,72,73]. Other problems that can be found are related to ring size dependence of NICS values [74].…”

Section: Introductionmentioning

confidence: 99%

A Critical Assessment of the Performance of Magnetic and Electronic Indices of Aromaticity

et al. 2010

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Abstract:The lack of reference aromatic systems in the realm of inorganic aromatic compounds makes the evaluation of aromaticity in all-metal and semimetal clusters a difficult task. To date, calculation of nucleus-independent chemical shifts (NICS) has been the most widely used method to discuss aromaticity in these systems. In the first part of this work, we briefly review our previous studies, showing some pitfalls of the NICS indicator of aromaticity in organic molecules. Then, we refer to our study on the performance of some aromaticity indices in a series of 15 aromaticity tests, which can be used to analyze the advantages and drawbacks of aromaticity descriptors. It is shown that indices based on the study of electron delocalization are the most accurate among those analyzed in the series of proposed tests, while NICS(1) zz and NICS(0) πzz present the best behavior among NICS indices. In the second part, we discuss the use of NICS and electronic multicenter indices (MCI) in inorganic clusters. In particular, we evaluate the aromaticity of two series of all-metal and semimetal clusters with predictable aromaticity trends by means of NICS and MCI. Results show that the expected trends are generally better reproduced by MCI than NICS. It is concluded that NICS(0) π and NICS(0) πzz are the kind of NICS that perform the best among the different NICS indices analyzed for the studied series of inorganic compounds.

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“…The lack of an immediate observable has resulted in a multiplicity of indices to quantify aromaticity, based on energetic [3] , geometric [4] , quantum chemical [5] or magnetic considerations [6][7][8][9][10] . A concept closely related to aromaticity is that of electron delocalization, of which the Multi Centre Bond Index (MCBI), recently introduced by our group [11][12][13][14] , has been shown to be a successful measure [15] . In the family of magnetic measures of aromaticity, one of the most popular indices is the so-called Nucleus Independent Chemical Shift (NICS) [6,7,16,17] which is the negative of the magnetic shielding computed at the centre of the ring for which the degree of aromaticity is to be assessed.…”

Section: Introductionmentioning

confidence: 99%

Multidimensionality of delocalization indices and nucleus‐independent chemical shifts in polycyclic aromatic hydrocarbons II: Proof of further nonlocality

2010

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1 AbstractIn a recent contribution we examined the effect of ten-and fourteencenter circuits on the Nucleus Independent Chemical Shifts (NICS) using Multicentre Bond Indices (MCBI) [1] . In this study the non-local contributions to the NICS are further investigated for a larger set of polycyclic aromatic hydrocarbons (PAH). To achieve this the NICS are predicted using the MCBI and compared with ab initio results. by the higher-order circuits encircling the ring at which it is evaluated, but also by the local aromaticity of the surrounding rings and occasionally, like in the case of Coronene, the NICS are even influenced by currents farther away in the molecule.

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On the performance of some aromaticity indices: A critical assessment using a test set

Cited by 272 publications

References 147 publications

Quantifying aromaticity with electron delocalisation measures

Quantifying aromaticity with electron delocalisation measures

A Critical Assessment of the Performance of Magnetic and Electronic Indices of Aromaticity

Multidimensionality of delocalization indices and nucleus‐independent chemical shifts in polycyclic aromatic hydrocarbons II: Proof of further nonlocality

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