Quantitative substituent effects in the Grignard reaction with silanes

Article abstract of DOI:10.1016/j.jorganchem.2007.05.009

Kinetics of reactions of ethyl- and phenylmagnesium chlorides with chlorosilanes, RMeSiCl₂, were investigated in diethyl ether under pseudo-first order conditions with a great excess of the Grignard reagent. Rate constants for alkyl substituted silanes correlate well with E_s(Si) steric parameters. A good linear correlation of rate data for substituted phenyl derivates with σ⁰ inductive constants together with correlations of the literature data rule out the resonance effect of substituents at least in nucleophilic displacement reactions at the silicon center. An attempt to calculate the steric constants for polar substituents was made. It appeared that the inductive constants σ^* derived from the carbon chemistry are not applicable to the silicon chemistry. New scales of parameters for description of polar and steric effects in the organosilicon chemistry need to be created.

Full text of DOI:10.1016/j.jorganchem.2007.05.009

Journal of Organometallic Chemistry 692 (2007) 3700–3705
www.elsevier.com/locate/jorganchem
Quantitative substituent effects in the Grignard reaction with silanes
1
*
Oleg Golubev, Dmitri Panov, Anu Ploom, Ants Tuulmets , Binh T. Nguyen
Institute of Organic and Bioorganic Chemistry, University of Tartu, Tartu 51014, Estonia
Received 2 April 2007; received in revised form 23 April 2007; accepted 7 May 2007
Available online 22 May 2007
Abstract
Kinetics of reactions of ethyl- and phenylmagnesium chlorides with chlorosilanes, RMeSiCl2, were investigated in diethyl ether under
pseudo-first order conditions with a great excess of the Grignard reagent. Rate constants for alkyl substituted silanes correlate well with
Es(Si) steric parameters. A good linear correlation of rate data for substituted phenyl derivates with r0 inductive constants together with
correlations of the literature data rule out the resonance effect of substituents at least in nucleophilic displacement reactions at the silicon
center. An attempt to calculate the steric constants for polar substituents was made. It appeared that the inductive constants r* derived
from the carbon chemistry are not applicable to the silicon chemistry. New scales of parameters for description of polar and steric effects
in the organosilicon chemistry need to be created.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Correlation analysis; Grignard reaction; Kinetics; Silanes; Substituent effects
1. Introduction
lies largely in the hydrolysis reactions of silicon compounds
to produce silicones but not less in the reactions for produc-
tion of a wide range of monomeric organosilicon com-
pounds.
The Grignard reaction with silanes is a particular
instance of nucleophilic displacements at the silicon center
since a Grignard reagent is one of the strongest nucleo-
philes applicable in common coupling reactions. In our
recent work [10] the reaction between methylvinyldichlo-
rosilane and a series of alkylmagnesium chlorides proved
to be a good test of applicability for steric constants Es(Si)
of alkyl substituents [11], further allowing calculation of
missing constants.
In this work we exploit the Grignard reaction with chlo-
rosilanes for testing the significance of the resonance effect
of substituents, using correlation of kinetic data for substi-
tuted phenylsilanes with r0 constants. Further we assess the
applicability of polar substituent constants r* derived from
reactions at carbon centers [12,13] to silicon chemistry.
Available in the literature data for nucleophilic displace-
ment reactions at the silicon center will be involved in the
discussion.
Grignard chemistry is a versatile method for the produc-
tion of organosilanes [1]. However, quantitative aspects of
the reaction have been little investigated. A small number
of kinetic studies of the Grignard reaction with silanes have
been published [2–10] and no attempts to ascertain the struc-
ture-reactivity relationships for the reaction were made until
our recent work [10].
We have launched an investigation into quantitative
aspects of the reactivity in the Grignard reaction with silanes
[6–10]. The main attention is focused on the structure-reac-
tivity relationships for the reaction. In parallel to this we
set out to revise the current approach to reactivity problems
of organosilicon compounds [11]. We confine ourselves to
nucleophilic substitutions at silicon. This is an area of both
commercial and academic interest. The commercial interest
*
Corresponding author.
E-mail addresses: dmitri.panov@ut.ee (D. Panov), ants.tuulmets@
ut.ee (A. Tuulmets).
1
Present address: Dow Corning Corporation, Midland, MI 48686-0995,
USA.
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.05.009

O. Golubev et al. / Journal of Organometallic Chemistry 692 (2007) 3700–3705
3701
2. Experimental
the flask and when the system was equilibrated at 20 ꢁC a
calculated amount of the silane (about 0.05 mL, providing
about 20-fold excess of the Grignard reagent) was injected
into the flask. The temperature change of the reaction solu-
tion was recorded as a plot of temperature vs. time. Use of
a differential method for calculation of rate constants [8]
eliminated the minor contribution of heat exchange with
the reaction vessel. The measurements were carried out in
duplicate or triplicate the rate constants being reproducible
within an accuracy better than 5%.
2.1. Materials
Commercial reagents were carefully purified. Reagent
grade magnesium shavings 99.8% Mg were purchased from
Fluka. The reagents and solutions were operated under dry
argon, and transferred by use of cannulas or syringes.
Methyltrichlorosilane, dimethyldichlorosilane, methyl-
phenyl-, and methylvinyldichloro-silanes were donated by
Dow Corning Corp. Methylchloromethyldichlorosilane was
purchased from Aldrich. Methylethyl-, methyl-n-butyl-,
methylisobutyl-, methyl-sec-butyl-, and methylisopropyldi-
chlorosilanes were prepared from corresponding alkylmag
nesium chlorides and methyltrichlorosilane. Methyl-4-meth-
oxy-, methyl-3-methoxy-, methyl-4-chloro-, methyl-3-
chloro-, and methyl-4-methylphenyldichlorosilanes were
synthesized from corresponding substituted phenylmagne-
sium bromides and methyltrichlorosilane.
Alkylmagnesium chlorides and substituted phenylmagne-
sium bromides were prepared in diethyl ether by conventional
methods [14] from corresponding commercial halides. Chlo-
robenzene does not react with magnesium even in boiling
diethyl ether, therefore ethereal solutions of phenylmagne-
sium chloride were prepared according to Gilman and Brown
[15] in an autoclave at 130 ꢁC.
3. Results and discussion
3.1. Rate constants
Kinetics of reactions of ethyl- and phenylmagnesium
chlorides with chlorosilanes were investigated under
pseudo-first order conditions with a great excess of Grignard
reagent. The rate measurements were carried out with 0.5 M
solutions of Grignard reagents in diethyl ether at 20 ꢁC. The
first order rate constants are collected in Table 1.
Phenylmagnesium chloride reacts faster under these
conditions, in line with its nucleophilicity superior to ethyl-
magnesium chloride. A noticeable rate accelerating effect of
polar substituents in silanes is also obvious. Steric effects of
alkyl substituents will be discussed in the next section.
2.2. Kinetic measurements
3.2. Steric effects of alkyl substituents
Kinetic experiments were carried out in a 100 ml two-
necked flask equipped with a thermostat, sealed with septa,
capped with an inert gas balloon, and equipped with a
magnetic stirrer and a thermometer. A 0.5 M solution of
the Grignard reagent (usually 50 mL) was transferred into
the flask and when the temperature of system was equili-
brated at 20 ꢁC a calculated amount of the silane (provid-
ing a 15–20-fold molar excess of the Grignard reagent) was
added.
At appropriate time points 1 mL aliquots were taken
from the homogeneous solution through a septum with a
syringe and quenched with a cool dry ethanol/pyridine
mixture. The solution was analyzed for the alkoxysilanes
formed in quenching, using a Varian 3700 gas chromato-
graph with a flame ionization detector.
The first order rate constants were calculated using the
peak areas for the initial and product silanes corrected
for the difference in sensitivity of the flame detector. The
reaction was usually monitored during the first or two
half-lives. The coupling followed excellent first order kinet-
ics. Virtually only primary products were detected by the
end of the monitoring time. Experiments were carried out
in duplicate or triplicate, the rate constants were reproduc-
ible within an accuracy of 5% or better.
The fast reactions were investigated in a thermostatic
flask equipped with a stirrer and a thermistor. The therm-
istor was connected through a bridge circuit to a PC. A
15 mL sample of the Grignard reagent was transferred into
In our previous paper [11] available in the literature
quantitative data concerning the reactivity of organosilicon
compounds were collected and the rate data for
Table 1
First order rate constants for Grignard reactions with chlorosilanes, and
corresponding substituent constants. Concentration of Grignard reagents
0.5 M
R in RMeSiCl2
k · 104 sꢀ1
Es(Si)a
r0 [13]
r* [13]b
EtMgCl
PhMgCl
Me
Et
nBu
iBu
iPr
sBu
Vinyl
ClCH2
Cl
2.00
–
10.33
7.58
–
5.72
4.17
–
7.00c
41.7c
61.6c
4.25
3.40
3.50
6.00
11.3
13.5
0
–
–
–
–
–
–
–
–
0
0
0
0
0
0
0.40
1.05
2.9
0.60
–
–
–
–
0
ꢀ0.149
0.618
0.467
0.157
0.123
8.83c
18.3c
–
4.50
–
–
ꢀ0.225
ꢀ0.405
ꢀ0.556
ꢀ0.67
–
–
–
–
–
–
–
–
–
–
Ph
0
4-MePh
4-MeOPh
3-MeOPh
4-ClPh
3-ClPh
a
ꢀ0.15
ꢀ0.16
0.06
0.27
0.37
–
–
–
Steric constants by Cartledge [11,16].
The r*-values for alkyl groups are taken to be zero [11,17,18].
Thermographic method (See Section 2).
b
c

3702
O. Golubev et al. / Journal of Organometallic Chemistry 692 (2007) 3700–3705
compounds with alkyl substituents were subjected to a cor-
relation analysis. Four sets of steric constants for alkyl sub-
stituents of silicon compounds were considered. Some
missing values were calculated and several corrections were
made. It appeared that the improved sets of parameters
were practically equivalent. Chronologically, the first
among them was the Es(Si) scale by Cartledge [16] and sub-
sequently we use this scale of parameters. Results of our
analysis corroborated former suppositions that alkyl sub-
stituents contribute to the reactivity of silicon compounds
exclusively with their steric effects, and that steric effects
in silicon compounds are additive. The kinetic data of this
work (Table 1) were allowed to a correlation analysis with
the reduced Taft equation matched for silicon compounds
(Eq. (1))
able charge development in the transition state manifested
by strong substituent effects of polar groups (cf. the data in
Table 1). As a whole, these few susceptibility parameters
found from Grignard reactions fit the range of available
d values for the reactions of organosilicon compounds [11].
3.3. The resonance effect of substituents
To correlate structural effects with chemical or physical
properties it is necessary to differentiate between steric and
electronic (polar) effects in relation to a property. Accord-
ing to current principles [19] the polar effect can be decom-
posed into inductive and resonance components.
While in traditional organic chemistry this issue has a
long history and protocols for quantitative separation of
the effects are available [12,13], the participation of d-orbi-
tals in the structure formation of silicon compounds has
been a subject of continuing debates [20–22]. Theoretical
studies of the SN2(Si) reaction and pentacoordinate silicon
intermediates or transition states show that d-orbitals are
unlikely to have any significant involvement in the bonding
in such species [21,22]. Streitwieser et al. [23] found that
bonds between Si and H, C, O and F are extensively polar-
ized with significant charge transfer. As a result Si–O and
Si–F bonds are dominated by ionic interactions, and
Si–H and Si–C bonds have an important ionic character.
Thus a resonance interaction requiring an overlap of
p- and/or d-orbitals should be considerably hindered. As
an unambiguous experimental test of the theoretical con-
siderations, correlation of kinetic data for substituted phe-
nylsilanes with r0 constants was implicated by Chvalovsky´
et al. [24]. By definition [13] the r0 constants measure the
inductive effect of substituted phenyl groups at the reaction
center. A linear correlation with r0 constants thus rules out
the conjugation of substituents with the reaction center.
In Fig. 2 the correlation of rate data for the reaction
between phenylmagnesium chloride and substituted meth-
ylphenyldichlorosilanes (from Table 1) with r0 constants
log k ¼ log ko þ dEsðSiÞ;
ð1Þ
where d is the susceptibility factor for steric effects.
From Fig. 1 it can be seen that rate constants for reac-
tions of ethylmagnesium and phenylmagnesium chlorides
with alkyl substituted chlorosilanes correlate well with
Es(Si) parameters. The regression coefficients are 1.81
0.18 and 0.64 0.11, respectively with corresponding cor-
relation coefficients 0.985 and 0.970. So far only one reac-
tion series can be brought for comparison, viz. the reaction
between alkylmagnesium chlorides and methylvinyldichlo-
rosilane [10] with d = 1.04 0.03 (R = 0.998).
The observed large dissimilarity of steric requirements
between the reaction series of present work is somewhat
unexpected. Although, conformations of a transition state
sterically favorable for the planar phenyl moiety may be
conceivable, such a great difference hardly can be explained
merely by structural diversities between ethyl and phenyl
groups. Provisionally, we tend to assign the extremely
small steric effect in the reaction with phenylmagnesium
chloride to a rather early transition state of the reaction.
This assumption is consistent with the considerable nucle-
ophilicity of the reagent and does not contradict a remark-
-Es(Si)
σo
0
0.2
0.4
0.6
0.8
-2.5
-0.3
-0.1
0.1
0.3
-2.7
-3.2
-3.7
-4.2
-4.7
-5.2
a
-3
b
-3.5
-4
Fig. 1. Correlation of rate data for the reactions between Grignard
reagents and alkylmethyldichlorosilanes with steric constants Es(Si). (a)
phenylmagnesium chloride and (b) ethylmagnesium chloride.
Fig. 2. Correlation of rate data for the reaction between phenylmagne-
sium chloride and methylphenyldichlorosilanes substituted in phenyl
group with inductive r0 constants.

O. Golubev et al. / Journal of Organometallic Chemistry 692 (2007) 3700–3705
3703
is shown. The regression coefficient q0 = 1.12 0.10
(R = 0.985) was found. The good linear correlation indi-
cates that the resonance effect of substituents is insignifi-
cant in the reaction if present at all. Also correlation data
for a variety of reactions in Table 2 provide a good evi-
dence of insignificance of the resonance effect at least in
nucleophilic displacement reactions at the silicon center.
Because of scarcity of kinetic data we included in Table 2
also correlations consisting of just three compounds, how-
ever, the correlations were good to excellent.
Then, according to Eq. (2), novel steric substituent con-
stants can be calculated from Eq. (3).
log k ꢀ log k0 ꢀ q ꢁ rꢁ
EsðSiÞ ¼
:
ð3Þ
d
In Table 3 results of the calculations are collected. The
values obtained for Es(Si) parameters are unreasonable to
senseless. If one does not discard promptly the calculation
procedure, one can surmise the incompatibility of Taft‘s
induction constants derived from carbon chemistry with
polar effects in silicon compounds. Indeed, a serious doubt
has been cast on the r* values for phenyl and vinyl groups
[24,31]. The authors have estimated for phenyl group
r* = 0.06 from the bromination reaction of organosilicon
hydrides instead of r* = 0.60 for carbon compounds, and
suggest that the inductive effect of vinyl group is compara-
ble to or less than that of phenyl group.
Some steric constants Es(Si) calculated using different r*
values are presented in Table 4. Reactions IV, V, and X seem
to be the most compatible with each other issuing compara-
ble and seemingly reasonable Es(Si) values at r* 6 0.06. For
chloromethyl group r* = 0.65 was estimated iteratively
assuming that steric requirements of the group should not
much differ from those of ethyl group. Similarly, from reac-
tion X the tabulated value r* = 0.40 for vinyl group leads to
an evidently overvalued Es(Si) = ꢀ 0.68 while r* value 0.06
suggested in the literature [24,31] gives a Es(Si) value ꢀ0.09
which is sufficiently concordant with imaginable dimensions
of the vinyl group.
3.4. Calculation of steric constants for polar substituents
Effects of aliphatic substituents on the reactivity of
organosilicon compounds have been described with the
Taft equation (Eq. (2)) [20,30], where the two last terms
express the independent contributions from inductive and
steric effects, respectively [12,13].
log k ¼ log k0 þ q ꢁ r ꢁ þdEs:
ð2Þ
The substituent constants in Eq. (2) have been defined in
organic reactions. At present it is understood that the steric
parameters derived from reactions of organic carbonyl
compounds are not suitable for description of steric effects
in reactions taking place at Si atoms [10,11,16,25]. For
alkyl substituents appropriate scales of parameters, e.g.
that of Es(Si) constants, have been developed [11,16]. How-
ever, the scales of steric constants still need to be expanded
to cover also polar substituents.
If one accepts the r* constants by Taft [12,13] for polar
substituents, and the r0 constants for substituted phenyl
groups, a simple procedure can be envisaged. Within a
reaction series susceptibility to the steric effect can be deter-
mined from a variety of alkyl substituents. A correlation
for substituted phenyl groups with r0 constants will give
q0 parameter which can be applied for q* in Eq. (2) pro-
vided r* values for phenyl substituents are calculated as
As an inevitable inference from the reasonings above we
must admit that the scale of r* inductive constants by Taft
cannot be applied to silicon chemistry. However, the
situation seems to be even more complicated. Examination
of Table 3 suggests a conclusion that the data cannot
be described by means of a two-parameter equation like
Eq. (2). Apparently one more variable needs to be involved
to unravel the structure-reactivity relationships in this
particular field. An additional evidence of this can be the
total failure of correlation of the data for reaction of
r ꢁ ðXC6H4ꢀÞ ¼ r0ðXC6H4ꢀÞ þ r ꢁ ðC6H5ꢀÞ:
Table 2
Correlation data for nucleophilic displacement reactions at the silicon center
Reaction, Solvent
Induction effect
Steric effect
na
q0
Rb
na
d
Rb
I. RMe2SiCl + Me3SiOLi, Et2O [25]
II. RMe2SiCl + PhMe2SiOLi, Et2O [25]
III. RMe2SiCl + Me2CHOLi, Et2O [25]
IV. RMe2SiCl + H2O, diox [26]
3
5
3
3
5
6
5
3
6
6
0.73 0.02
0.74 0.09
1.11 0.08
1.20 0.11
1.02 0.08
1.85 0.16
0.83 0.08
0.35 0.04
2.41 0.06
1.12 0.10
0.999
0.976
0.997
0.996
0.990
0.989
0.987
0.994
0.999
0.985
7
6
7
8
7
6
–
–
–
4
1.59 0.29
1.31 0.16
1.62 0.11
2.30 0.11
1.61 0.09
1.59 0.19
–
0.924
0.971
0.988
0.993
0.992
0.973
–
V. RSiCl3 + tBuOLi, Et2O [27]
VI. RSiCl3 acetolysis, Ac2O [28]
VII. RMe2SiCl + tBuOLi, Et2O [27]
VIII. RMe2SiH acidic solvolysis [29]
IX. RMe2SiH alkaline solvolysis [24]
X. RMeSiCl2 + PhMgCl, Et2Oc
–
–
–
–
0.64 0.11
0.970
a
Number of compounds in the correlation.
Correlation coefficient.
This work.
b
c

3704
O. Golubev et al. / Journal of Organometallic Chemistry 692 (2007) 3700–3705
Table 3
Calculated steric constants Es(Si) for polar substituents. Numeration of reaction series as in Table 2
Substituent
I
II
III
IV
V
VI
X
Ph
ꢀ0.301
ꢀ0.322
0.038
ꢀ0.356
ꢀ0.368
ꢀ0.028
ꢀ0.003
ꢀ0.105
ꢀ0.750
ꢀ0.557
ꢀ0.542
ꢀ0.288
–
ꢀ0.683
ꢀ0.658
ꢀ0.313
ꢀ0.623
–
ꢀ0.952
ꢀ0.967
ꢀ0.394
ꢀ0.724
–
ꢀ1.45
ꢀ1.46
X–C6H4–a
ClCH2–
Cl2CH–
BrCH2–
PhCH2–
a
ꢀ1.39
ꢀ1.29
–
–
–
–
ꢀ0.64
0.023
–
–
–
ꢀ0.031
ꢀ0.205
ꢀ0.538
ꢀ0.489
ꢀ0.356
ꢀ0.293
Average value for substituted phenyl groups.
Table 4
Steric constants Es(Si) calculated using different r* values
kinetic data the steric constants for polar substituents
involving the inductive constants r* by Taft. It appeared
that the r* constants derived from the carbon chemistry
are not applicable to the silicon chemistry. As the main
conclusion, new scales of parameters for description of
polar and steric effects in the organosilicon chemistry need
to be created.
Reaction series
Phenyl group
Chloromethyl group
0.60
0.06
0.00
1.05
0.65
III
IV
V
VI
X
ꢀ0.56
ꢀ0.68
ꢀ0.95
ꢀ1.45
ꢀ1.46
ꢀ0.19
ꢀ0.40
ꢀ0.61
ꢀ0.82
ꢀ0.43
ꢀ0.15
ꢀ0.37
ꢀ0.57
ꢀ0.75
ꢀ0.32
ꢀ0.29
ꢀ0.31
ꢀ0.39
–
ꢀ0.014
ꢀ0.10
ꢀ0.14
–
ꢀ0.64
ꢀ0.061
Acknowledgements
This work was financially supported by the Dow Corn-
ing Corporation (Midland, USA) and the Estonian Science
Foundation (Grant No. 6512).
ethylmagnesium chloride (Table 1) with novel Es(Si) and r*
values estimated above as well as with the tabulated values.
It cannot be excluded that our observations may be
related to the complex character of the inductive effect dis-
covered only recently [32,33]. The principle is that a simple
inductive effect can be observed only on the interaction
with a charged group. When both interacting groups are
less polar, the effect must be expressed by two terms. The
second term is small, it depends only on the first atom of
the substituent and decreases with the distance more stee-
ply. Its physical meaning is still unclear. Note that the
novel conception of the inductive effect stems from the car-
bon chemistry. If applicable to the silicon chemistry, the
proportions between the components of the effect need
not remain the same.
References
[1] B. Arkles, in: G.S. Silverman, P.E. Rakita (Eds.), Handbook of
Grignard Reagents, Marcel Dekker, New York, 1996 (Chapter 32).
[2] A.F. Reid, C.J. Wilkins, J. Chem. Soc. (1955) 4029.
[3] R.J.P. Corriu, B. Henner, J. Organomet. Chem. 102 (1975) 407.
[4] A. Tuulmets, M. Horak, T. Koopere, J. Ruotsi, Org. React. (USSR)
˜
˜
19 (1982) 102;
A. Tuulmets, M. Horak, T. Koopere, J. Ruotsi, Chem. Abstr. 99
˜
˜
(1983) 53836.
[5] M. Sassian, D. Panov, A. Tuulmets, Appl. Organomet. Chem. 16
(2002) 525.
[6] A. Tuulmets, D. Panov, M. Sassian, Tetrahedron Lett. 44 (2003)
3943.
Despite scarce kinetic data for organosilicon reactions,
we hope to be able to cast light on these challenging prob-
lems through an extensive statistical treatment of all avail-
able data.
[7] A. Tuulmets, B.T. Nguyen, D. Panov, M. Sassian, J. Ja¨rv, J. Org.
Chem. 68 (2003) 9933.
[8] A. Tuulmets, B.T. Nguyen, D. Panov, J. Org. Chem. 69 (2004) 5071.
[9] D. Panov, A. Tuulmets, B.T. Nguyen, J. Organomet. Chem. 691
(2006) 4076.
[10] D. Panov, A. Ploom, A. Tuulmets, Phosphorus, Sulfur, and Silicon
181 (2006) 2807.
4. Conclusions
[11] A. Ploom, D. Panov, A. Tuulmets, ARKIVOC (5) (2006) 37.
[12] R.W. Taft Jr., in: M. Newman (Ed.), Steric Effects in Organic
Chemistry, Wiley, New York, 1956 (Chapter 13).
[13] J. Shorter, Correlation Analysis in Organic Chemistry, Clarendon
Press, Oxford, 1973.
[14] B.J. Wakefield, Organomagnesium Methods in Organic Synthesis,
Academic Press, New York, 1995.
[15] H. Gilman, R.E. Brown, J. Am. Chem. Soc. 52 (1930) 3330.
[16] F.K. Cartledge, Organometallics 2 (1983) 425.
[17] M. Charton, J. Am. Chem. Soc. 97 (1975) 3691.
[18] D.F. DeTar, J. Org. Chem. 45 (1980) 5166.
[19] C.K. Ingold, Structure and Mechanism in Organic Chemistry,
Cornell University Press, Ithaka, NY, 1953.
[20] V.P. Mileshkevich, N.F. Novikova, Usp. Khim. 50 (1981) 85.
[21] J.Y. Corey, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of
Organic Silicon Compounds, Wiley, New York, 1989 (Chapter 1).
Rate constants for reactions of ethyl- and phenylmagne-
sium chlorides with alkyl substituted chlorosilanes correlated
well with Es(Si) steric parameters thus proving recurringly
applicability of these constants in silicon chemistry.
Rate constants for the reactions with substituted phenyl-
silanes, involving also the literature data, were correlated
with r0 inductive constants. The obtained good linear cor-
relations ruled out the conjugation of substituents with the
reaction center well in line with the results of quantum
chemical calculations.
It was concluded that only steric and inductive effects
are operating. Next an attempt was made to calculate from

O. Golubev et al. / Journal of Organometallic Chemistry 692 (2007) 3700–3705
3705
[22] Y. Apeloig, M. Karni, in: Z. Rappoport, Y. Apeloig (Eds.), The
Chemistry of Organic Silicon Compounds, vol. 2, Wiley, New York,
1998 (Chapter 1).
[27] K. Ka¨ppler, U. Scheim, K. Ruhlmann, Phosphorus, Sulfur, and
¨
Silicon 106 (1995) 203.
[28] K. Ka¨ppler, A. Porzel, U. Scheim, K. Ruhlmann, J. Organomet.
¨
[23] S. Gronert, R. Glaser, A. Streitwieser, J. Am. Chem. Soc. 111 (1989)
3111.
[24] J. Hetfleijsˇ, F. Maresˇ, V. Chvalovsky´, Coll. Czechoslov. Chem.
Commun. 30 (1965) 1643.
Chem. 402 (1991) 155.
[29] J.E. Baines, C. Eaborn, J. Chem. Soc. (1956) 1436.
[30] L.H. Sommer, Stereochemistry, Mechanism and Silicon, McGraw-
Hill, New York, 1965.
[25] K. Ka¨ppler, U. Scheim, K. Ruhlmann, A. Porzel, J. Organomet.
¨
[31] J. Hetfleijsˇ, F. Maresˇ, V. Chvalovsky´, Coll. Czechoslov. Chem.
Commun. 37 (1972) 1713.
Chem. 441 (1992) 15.
[26] N. Shimizu, N. Takesuke, A. Yamamoto, T. Tsutsumi, S. Yasuhara,
Y. Tsuno, Chem. Lett. (1992) 1263.
[32] O. Exner, S. Bo¨hm, J. Phys. Org.Chem. 17 (2004) 124.
[33] O. Exner, S. Bo¨hm, J. Phys. Org.Chem. 19 (2006) 393.