Lewis Acidity Expressed in Neutral Electron-Rich Aluminum(III) Complexes:  An Example of Ligand-Defined Catalysis

Nelson, Scott G.; Kim, and Beon-Kyu; Peelen, Timothy J.

doi:10.1021/ja002415q

Cited by 73 publications

(50 citation statements)

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“…A compound with a significantly more pronounced trigonal monopyramidal geometry has been reported by Nelson [9], who combined the ligand (CF 3 S(O 2 ) NCH(i-Pr)CH 2 ) 2 Nbenz with trimethyl aluminum. The resulting structure (figure 8) has two nitrogens and the methyl equatorial and the datively bonding nitrogen axial.…”

Section: )C(ch 3 )Nn(h)c(s)n(h)hph)mentioning

confidence: 81%

“…Of special interest is the catalytic activity of many three [1 -3] and four [4 -7] coordinate aluminum and gallium complexes. These are Lewis acid catalysts, which work by coordinating an extra substituent [8,9]. Efforts to improve their catalytic activity have often focused on the addition of new ligands to increase the Lewis acidity of the metals.…”

Section: Introductionmentioning

confidence: 99%

“…E-mail: ahutchison@cedarville.edu However, there is another way to approach this issue. Since the catalytic mechanism involves the coordination of an extra substituent, a geometry which favors this addition should lead to increased catalytic activity [9]. This paper will introduce a new method of quantifying the geometry of four coordinate group thirteen compounds as a first step towards the design of ''geometrically rational'' catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…A square planar geometry would provide two such sites. Therefore, for catalytic applications and assuming all ligand effects are equal, a compound that possesses a geometry close to trigonal monopyramidal would be expected to be a superior Lewis acid by comparison to one adopting the more common tetrahedral geometry [9]. If a number could be assigned to a compound's geometry that would accurately reflect how distorted this compound was from Td towards some geometry more likely to coordinate a fifth substituent, that value could, at a glance, convey important information about the compound.…”

Section: Introductionmentioning

confidence: 99%

“…Although the THC value can show that a compound is distorted from the tetrahedral geometry, it does not necessarily show what geometry the molecule has been distorted to. In light of the correlation of Lewis acidity and geometry [9], we were interested in distortion towards a trigonal monopyramidal, or an unlikely square planar, geometry as a means of measuring the ability of a four-coordinate compound to coordinate a fifth ligand. Therefore, it was still deemed worthwhile to develop a new method of quantifying geometry.…”

Section: Introductionmentioning

confidence: 99%

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The four coordinate geometric parameter: A new quantification of geometry for four coordinate aluminum and gallium

Hutchison¹,

Mitra²,

Atwood³

2005

Main Group Chemistry

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The chemistry of aluminum and gallium compounds has long been a major area of research. Much of this interest stems from the compound's use as Lewis acid catalysts. Efforts to create better aluminum and gallium catalysts have often focused on the addition of new ligands to increase the Lewis acidity of the metals. However, a four coordinate Lewis acid catalyst generally must add a fifth substituent during its catalytic cycle, so the degree to which its geometry encourages this addition will also affect its activity. To help determine the degree to which a four coordinate compound is geometrically optimized to take on a fifth substituent, we have created the four coordinate geometric parameter (FGCP). The FGCP of a compound can be calculated by a simple formula utilizing the ligand-metal-ligand angles of the structure. A high FGCP value indicates a compound with an open space for a fifth substituent, while a lower FGCP value indicates a compound with a more tetrahedral geometry. A negative FGCP suggests a geometry approaching square planar, which is admittedly very unlikely for an aluminum or gallium compound. The FGCP values have been calculated for a number of structures reported in the literature, demonstrating that the method is useful for quantifying the geometry of a variety of known group thirteen compounds.

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Section: )C(ch 3 )Nn(h)c(s)n(h)hph)mentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations