A novel insight into the inductive effect in silicon chemistry

Ploom, Anu; Tuulmets, Ants

doi:10.1016/j.jorganchem.2008.12.001

Cited by 5 publications

(6 citation statements)

References 26 publications

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“…In this type of bonding, the inductive effects play a nonanticipated important role. 26 To understand the nature and extent of the covalent contribution to the Ti-O bonding, an interaction diagram was devised for the simplest compound, 7, in its optimized bent (121.96°) and collinear Ti-O-H conformation using Counterpoise DFT 27 (Figure 8).…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the Oxygen π-Donation in Permethyltitanocene Silanolates and Alcoholates

et al. 2009

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5), and t Bu (6) were prepared by protolysis of the titanium-methylene bond in singly tucked-in permethyltitanocene [Cp*Ti(III)(η 5 :η 1 -C 5 Me 4 CH 2 )] with the respective silanols or tert-butanol. Their electronic transitions from the ground-state molecules to their first excited states (dominantly a 1a 1 f b 2 transition) occur in the range 1300-1800 nm, originating from π-donation from oxygen lone pair electrons to the Ti-O bond (as found by Andersen et al. J. Am. Chem. Soc. 1996, 118, 1719. The X-ray crystal structures of 2-4 and 6 revealed that steric effects of substituents R′ change the geometry of the titanocene moiety only negligibly. DFT calculations of the 1a 1 f b 2 transition for optimized structures of 2, 4, 6, [Cp* 2 Ti(III)OH] (7), and [Cp* 2 Ti(III)OMe] (8) reproduced the dependence of experimental λ(1a 1 f b 2 ) on electron donation/attraction properties of R′ and revealed that the decrease of the oxygen π-donation is accompanied with an increase in negative natural charge on the OR′ group. The observed increase of λ exp (1a 1 f b 2 ) in the order of substituents R′, Me < t Bu < H < Ph < Si i Pr 3 < SiPh 3 ∼ Si(O t Bu) 3 < (c-C 5 H 9 ) 7 Si 8 O 12 (SIPOSS cluster), thus indicates the decrease of Ti-O π-interaction with an increased polarity of the Ti-O bond. The DFT calculations of 7 with the naturally bent and collinear Ti-O-H conformation showed only a small effect of bending on the oxygen π-donation.

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Section: Resultsmentioning

confidence: 99%

Evaluation of the Oxygen π-Donation in Permethyltitanocene Silanolates and Alcoholates

et al. 2009

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“…In addition, the results reaffirm that alkyl substituents contribute to the reactivity exclusively with steric effects. [25][26][27] Additionally, the interrelation between the steric factor and the bulkiness of both Grignard reagents is evident.…”

Section: Tablementioning

confidence: 97%

A Kinetic View of the Mechanism of the Grignard Reaction with Alkoxysilanes

Ploom

Tuulmets

Panov

et al. 2015

Phosphorus, Sulfur, and Silicon and the Related Elements

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RUNNING HEAD: The Grignard reaction with alkoxysilanes ABSTRACT The kinetics of the reaction of n-butyl-and isopropylmagnesium chloride with alkyltriethoxysilanes (RSi(OEt) 3 ) in diethyl ether were determined. The rate constants correlate well with the steric parameters E s (Si). The resulting steric factors δ fit the range of available susceptibility values for the reactions of organosilicon compounds. The thermodynamic activation parameters for six reactions of ethoxysilanes with alkylmagnesium chlorides in dibutyl ether were determined. The entropy values indicated that two Grignard molecules are involved in the transition state of the reaction. From the correlation analysis of the activation enthalpies for the reactions, it appeared that the inductive effect controls the rate of replacement more considerably than steric requirements in the transition state.

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“…[4][5][6] Recently we have carried out a revision of quantitative data regarding the reactivity of organosilicon compounds in light of views that stem from organic reactions at the carbon atom. [7][8][9][10] It was found that in structure-reactivity analysis for organosilicon compounds, as opposed to carbon compounds, the Taft E S scale of steric parameters is not applicable, 7,8 and the inductive effect of substituents must be expressed by two terms, involving one that describes electronegativity. 10 Cartledge 11 has defined a set of E S (Si) parameters for alkyl groups from reaction rates of silicon compounds, and these constants appeared to be in a good correlation with 2504 A. PLOOM ET AL.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10] It was found that in structure-reactivity analysis for organosilicon compounds, as opposed to carbon compounds, the Taft E S scale of steric parameters is not applicable, 7,8 and the inductive effect of substituents must be expressed by two terms, involving one that describes electronegativity. 10 Cartledge 11 has defined a set of E S (Si) parameters for alkyl groups from reaction rates of silicon compounds, and these constants appeared to be in a good correlation with 2504 A. PLOOM ET AL. ν parameters derived by Charton 12 from replacement reactions at sp 3 -carbon.…”

Section: Introductionmentioning

confidence: 99%

“…8 Further we extended the E S (Si) scale for several polar substituents, the data for which were not previously available. 10 The novel protocol for the correlation analysis in organosilicon chemistry proved to be applicable to all available experimental data for nucleophilic replacements and some other reactions at the silicon center, 8,10 including acid-and base-catalyzed hydrolyses, bromination, Grignard reactions, etc.…”

Section: Introductionmentioning

confidence: 99%

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Steric Parameters for Substituents Bound to Atoms of Silicon and Some Other Elements of the Third Period

Ploom

Tuulmets

Järv

2010

Phosphorus, Sulfur, and Silicon and the Related Elements

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The kinetics of a tetraethoxysilane reaction with n-butylmagnesium chloride, stoichiometrically monosolvated with isopropyl ether or with methyl tert-butyl ether, was studied in toluene. The pseudo-first-order rate constants determined at a great excess of Grignard reagent were used for separation of the appropriate equilibrium and rate constants. Equilibrium constants for five alkyl ether ligands at the magnesium center are in an excellent correlation with isosteric E S (Si) parameters. It was concluded that these constants should be applicable to all elements of the third period of the periodic table.

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A novel insight into the inductive effect in silicon chemistry

Cited by 5 publications

References 26 publications

Evaluation of the Oxygen π-Donation in Permethyltitanocene Silanolates and Alcoholates

Evaluation of the Oxygen π-Donation in Permethyltitanocene Silanolates and Alcoholates

A Kinetic View of the Mechanism of the Grignard Reaction with Alkoxysilanes

Steric Parameters for Substituents Bound to Atoms of Silicon and Some Other Elements of the Third Period

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