The 16 and 18 electron rule in organometallic chemistry and homogeneous catalysis

Tolman, Chadwick A.

doi:10.1039/cs9720100337

Cited by 378 publications

(175 citation statements)

References 3 publications

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“…As such, a total of 16 electrons represent the maximum population for a stable square planar complex [9,19]. This is sometimes referred to as the ''16-electron rule'' [6] or added to the 18-electron rule to become the ''16 and 18 electron rule'' [10], but most often is just recognized as the most consistent exception to the 18-electron rule.…”

Section: Other Compound Geometriesmentioning

confidence: 99%

“…Much like the more common octet rule, the 18-electron rule is not always strictly obeyed and is subject to a number of apparent exceptions [10]. Thus, while this tool is extremely useful in predicting stability, examples of stable metal complexes with more or less than 18 valence electrons are also fairly common [1,6,9].…”

Section: Introductionmentioning

confidence: 99%

“…This basic relationship is commonly referred to as the ''18-electron rule'', which has become a guiding principle of inorganic chemistry, particularly in organometallic chemistry [8][9][10]. It should be pointed out that some use the terms ''18-electron rule'' and ''effective atomic number (or EAN) rule'' interchangeably [9,[11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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The 18-electron rule and electron counting in transition metal compounds: theory and application

Rasmussen

2015

ChemTexts

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The 18-electron rule and the corresponding methods for counting the total valence electrons of transition metal complexes are among the most useful basic tools in modern inorganic chemistry, particularly in its application to organometallic species. While in its simplest representation, the 18-electron rule is explained in that a closed, stable noble gas configuration of ns 2 (n-1)d 10 np 6 is achieved with 18 valence electrons, this does not adequately explain the trends and exceptions seen in practice. As such, this report presents a deeper discussion of the 18-electron rule via molecular orbital models, stressing the roles of both r-and p-bonding effects. This discussion thus aims to provide a better understanding of the relationship between electron count and stability, while also illustrating which factors can determine adherence (or not) to this commonly utilized rule. Lastly, the two common methods for electron counting (ionic and covalent models) are also presented with practical examples to provide the complete ability to apply the 18-electron rule.

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Section: Other Compound Geometriesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The 18-electron rule and electron counting in transition metal compounds: theory and application

Rasmussen

2015

ChemTexts

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“…These 16-electron complexes can act as precursors, intermediates or products in several catalytic processes, where they can participate in associative elementary steps (in which they are readily converted into a 18-electrons compound) or in associative reactions, in which they can act as a 14-electrons species [1][2][3] . The existence of cis → trans isomerism in square planar d 8 complexes is well known.…”

Section: Introductionmentioning

confidence: 99%

On the cis -> trans isomerization of the square-planar [Pt(Cl)(SnCl3)(PH3)2] compound: ab initio gas phase reaction mechanism and solvent effects using continuum models

Rocha¹,

Almeida²

2000

J. Braz. Chem. Soc.

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A isomerização cis → trans do composto quadrático plano d 8 [Pt(Cl)(SnCl 3 )(PH 3 ) 2 ] foi investigada utilizando-se o nível ab initio de cálculo MP4(SDQ)//MP2. As estruturas otimizadas, localizadas na superfície de energia potencial em fase gasosa, indicam que esta reação se processa através de um estado de transição quase-tetraédrico. A influência dos efeitos eletrônicos dos ligantes no mecanismo da reação foi investigada utilizando-se o método de Análise de Decomposição de Carga (CDA), o qual forneceu suporte para a compreensão do forte efeito trans do ligante SnCl 3 . O efeito devido ao solvente na energia de reação em fase gasosa foi avaliado utilizando-se os modelos contínuos SCRF e IPCM. Em ambos os casos um aumento na barreira de energia para o processo foi observado, sendo que a estabilidade termodinâmica dos isômeros cis e trans foi alterada pela solvatação.The cis → trans isomerization of the d 8 square planar [Pt(Cl)(SnCl 3 )(PH 3 ) 2 ] compound was investigated at the MP4(SDQ)//MP2 level of theory. The optimized structures located on the gasphase potential energy surface indicate that this reaction proceeds through a quasi-tetrahedral transition state. The influence of electronic effects of the ligands on the reaction mechanism was investigated with the Charge Decomposition Analysis (CDA) method, which gave support to understand the strong trans effect of the SnCl 3 ligand. The solvent effect on the gas phase energy reaction was evaluated using the SCRF and IPCM continuum models. In both cases, an increase on the energy barrier for the process was observed and, the thermodynamical stability of the cis and trans isomers was changed upon solvation.

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“…These binding energies are among the highest for the complexes formed on pristine graphene and at the 3N C -V C -defect. Both of these sandwich structures satisfy Langmuir's 18-electron rule [45,46] for transition metal complexes, which is also used to explain the stability of the Cr(η 6 -C 6 H 6 ) 2 molecule. In the latter, 6 π-electrons from each benzene mix with the 6-electrons from the chromium atom to form a 18-electron closed-shell configuration.…”

mentioning

confidence: 99%

Stabilizing graphene-based organometallic sandwich structures through defect engineering

Dev

Reinecke

2015

Phys. Rev. B

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The 16 and 18 electron rule in organometallic chemistry and homogeneous catalysis

Cited by 378 publications

References 3 publications

The 18-electron rule and electron counting in transition metal compounds: theory and application

The 18-electron rule and electron counting in transition metal compounds: theory and application

On the cis -> trans isomerization of the square-planar [Pt(Cl)(SnCl3)(PH3)2] compound: ab initio gas phase reaction mechanism and solvent effects using continuum models

Stabilizing graphene-based organometallic sandwich structures through defect engineering

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