Si-Fluoro substituted quasisilatranes (N → Si) FYSi(OCH2CH2)2NR

Article abstract of DOI:10.1016/j.jorganchem.2008.09.010

The reaction of fluorosilanes XYSiF₂ (X = Y = F; X = F, Y = Ph; X = Ph, Y = Me) with diethanolamines and their O-trimethylsilyl derivatives affords novel Si-fluoro substituted quasisilatranes 3, 5 and 9. These compounds were characterized by th

Full text of DOI:10.1016/j.jorganchem.2008.09.010

Journal of Organometallic Chemistry 694 (2009) 607–615
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Si-Fluoro substituted quasisilatranes (N ? Si) FYSi(OCH2CH2)2NR
Alexander A. Korlyukov a, Konstantin A. Lyssenko a, Mikhail Yu. Antipin a, Ekaterina A. Grebneva b,
Aleksander I. Albanov b, Olga M. Trofimova b, Eleonora A. Zel’bst b, Mikhail G. Voronkov b,
*
a A.N. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Street, 119991 Moscow, Russia
b A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Street, 664033 Irkutsk, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 May 2008
Received in revised form 7 August 2008
Accepted 2 September 2008
Available online 11 September 2008
The reaction of fluorosilanes XYSiF2 (X = Y = F; X = F, Y = Ph; X = Ph, Y = Me) with diethanolamines and
their O-trimethylsilyl derivatives affords novel Si-fluoro substituted quasisilatranes 3, 5 and 9. These
compounds were characterized by the multinuclear NMR spectroscopy and X-ray diffraction analysis.
Experimental and theoretically calculated electron density distribution functions in crystal structure of
9 have shown that the N ? Si coordination bond corresponds to polar bond with pronounced ionic con-
tribution. Calculated N ? Si bond order in the compound 9 does not exceed 1/3 of the normal Si–N bond.
A strong N ? Si coordination bond exists in compounds 3, 5 and 9 the length of which varies in the range
1.98–2.175 Å.
Keywords:
Pentacoordinate silicon
Fluorosilanes
Ó 2008 Published by Elsevier B.V.
X-ray diffraction
Quantum chemical calculations
Electron density distribution
R2
R1
1. Introduction
N
Silatranes XSi(OCH2CH2)3N, pentacoordinate tricyclic silyl
derivatives of triethanolamine, have been widely studied owing
to the peculiarities of their electronic and molecular structure
and wide range of biological activity that they possess [1a–e].
These compounds have the N ? Si transannular bond the strength
of which depends on the nature of X substituent [1e].
F
O
XSiF3
1, 2
+
Me3SiOCH2CH2NR1R2
Si
F
-Me3SiF
X
X = Ph (1); R1 = R2 = H; R1 = H, R2 = Me;
X = F (2);
R1 = R2 = H; R1 = H, R2 = Me; R1 = R2 = Me.
The formation of the monocyclic or bicyclic compounds with
N ? Si coordination bond from mono or dialkanolamines is appre-
ciably affected by the substituent nature at the silicon and the
nitrogen atoms [2a–d]. Thus, the intramolecular coordination in
compounds R4ꢀnSiðOCH2CH2Þ NR0 (R0 = H, alkyl; n = 1, 2) is com-
We have recently found that the reaction of PhSiF3 (1) with ethanol-
amine and its N-methyl or N,N0-dimethyl derivatives is a convenient
method for the synthesis of the related pentacoordinate fluoro com-
plexes with N ? Si coordination bond [6].
n
3ꢀn
pletely lacking when R – electron-donating Me groups [2c,3a,3b],
while electron-withdrawing phenyl ligands (R = Ph, n = 2) at silicon
favors sufficiently strong intramolecular N ? Si bonding [4]. It has
been also shown the pentacoordination at silicon in phenyldifluoro
and trifluoro monocyclic compounds prepared by the transsilyla-
tion of phenyltrifluorosilane PhSiF3 (1) or tetrafluorosilane SiF4
(2) with O-trimethylsilyl derivatives of monoalkanolamines [5].
Men
N
H2-n
F
F
O
Si
F
PhSiF3 + HOCH2CH2NH2-nMen
1
-PhH
n = 0-2
The obtained results prompted us to examine the potential of orga-
nylfluorosilanes in the preparation of the related hypervalent sili-
con compounds. It should be noted that in the above fluoro
* Corresponding author. Tel.: +7 3952 426400; fax: +7 3952 419346.
E-mail address: voronkov@irioch.irk.ru (M.G. Voronkov).
0022-328X/$ - see front matter Ó 2008 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2008.09.010

608
A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
compounds N ? Si intramolecular bonding was studied in the solu-
tions and supported by the 19F and 29Si NMR data [5,6]. The struc-
tural investigations of bicyclic pentacoordinate derivatives of
dialkanolamines are scare and mainly concerned aryl substituted
compounds or spirochelates the silicon atom of which is connected
with four oxygen atoms [2c]. No X-ray data are available for related
compounds bearing a fluoro ligand at the silicon atom.
We report here the synthesis of new pentacoordinate bicyclic
fluorosilanes derived from diethanolamine and its N-methyl deriv-
ative, their X-ray studies as well as N ? Si chemical bonding
nature.
Me
N
PhSiF3 + (ROCH2CH2)2NMe
O
Si
O
-2 RF
1
Ph
F
R = H, Me3Si
5
Scheme 2.
Me
N
2. Results and discussion
2.1. Synthesis
Ph2SiF2
+
(ROCH2CH2)2NMe
R = H, Me3Si
O
O
Si
-2 RF
The reaction of PhSiF3 (1) with diethanolamine (Scheme 1a)
proceeds via the cleavage of the Ph–Si bond under mild conditions
to afford a solid product the 19F and 29Si NMR data of which differ
from those for pure compound 3. The latter was obtained by treat-
ment of O,O0-bissilylated diethanolamine with gaseous SiF4 (2) in
hexane (Scheme 1b). The product of the reaction (Scheme 1a) is
found to be a 1:1 mixture of bicyclic pentacoordinate compound
3 and its hydrofluoride 4. It is suggested by elemental analysis data
which are averaged between those for compounds 3 and 4. In the
crude product compound 4 was identified by its typical 29Si quartet
at d ꢀ127.2 ppm (JSi–F = 208 Hz) which is in the range characteristic
of related pentacoordinate silicon compounds [5]. A broadened 19F
signal (d ꢀ117.4 ppm) was observed in the 19F NMR spectrum of
the reaction product supporting the 3 ¢ 4 rapid equilibrium in
DMSO-d6 solution.
6
Ph Ph
7
Scheme 3.
H
N
MePhSiF2
+
(HOCH2CH2)2NH
O
Si
O
-HF
-PhH,
8
Me
F
9
In contrast to the reaction (Scheme 1a), replacement of fluoro
atoms takes place by treatment of PhSiF3 with N-Me-diethanola-
mine or its bissilylated derivative resulting in pentacoordinate
compound 5 (Scheme 2).
In a similar way, bicyclic compound 7 was prepared from di-
phenyldifluorosilane Ph2SiF2 (6) in 53% yield (Scheme 3).
Meanwhile, the cleavage of the Ph–Si bond in the initial silane is
observed when the phenyl group is replaced by a methyl one
(Scheme 4).
Scheme 4.
Obtained compounds were named quasisilatranes [7] (cf. pseu-
do-silatranes [8a,8b], 2/3-silatrane [9]) because of some their
structural similarity with silatranes.
Evidence that all of the new compounds 3, 5 and 9 have penta-
coordinate structure in solution DMSO-d6 is obtained from the 29Si
and 19F NMR spectral data which are within the range typical for
pentavalent silicon compounds. From Table 1 follows that the
29Si signals of 3, 5 and 9 appear at higher field as the substituent
become more electron-withdrawing.
Note that the compound 9 is the first example of the related
pentacoordinate compounds having an alkyl substituent at the sil-
icon atom.
All compounds were isolated as air-sensitive crystals, insoluble
in non-polar organic solvents and soluble in polar solvent such as
DMF and DMSO only. The latter was used as the solvent for NMR
studies.
Because of the presence of the intramolecular N ? Si bond the
diastereotopy of the protons of the CH2N and CH2O groups is ob-
served in the 1H NMR spectra of compounds 3, 5 and 9.
H
N
H+
X = Ph (1), R = H
-PhH, -HF
(1a)
3
+
O
O
Si
F
F
F
XSiF3 + (ROCH2CH2)2NH
4
H
N
1, 2
X = F (2), R = Me3Si
O
Si
O
(1b)
-Me3SiF
F
F
3
Scheme 1.

A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
609
Table 1
29Si Chemical shifts (ppm) in DMSO-d6 for quasisilatranes 3, 5 and 9 and related
diphenyl compounds 7 and 10 for comparison
3
5
7
9
10a
d (29Si)
ꢀ113.4
ꢀ80.3
ꢀ44.0
ꢀ82.1
ꢀ62.0 [10]
ꢀ48.1 [10]
10a: Ph2Si(OCH2CH2)2NH.
2.2. X-Ray structures of crystals 3, 5 and 9
The molecular structures of compounds 3, 5 and 9 are depicted
in Figs. 1–3. Selected bond lengths and angles are listed in Table 2.
The X-ray crystallographic experimental parameters used for crys-
tal structure analysis are summarized in Table 3.
The geometry of Si atom coordination centre in crystals of qua-
sisilatranes can be described as almost ideal (for 3) or slightly dis-
torted trigonal bipyramid (TBP) (for 5 and 9). The axial positions
are occupied by N1 and F1 atoms while the equatorial plane is
formed by two oxygen atoms and the carbon atom (Me, Ph groups)
or F2 atom.
The N–Si distance is in the same range for all compounds and
much shorter than the sum of the van der Waals radii of the silicon
and nitrogen atoms (3.65 Å) [11], that indicates coordination bond-
ing between them. As expected, the presence of a fluoro substitu-
ent in the axial position has profound effect on the N ? Si bond
length in quasisilatranes. Thus, the N–Si distance in 3 (1.981 Å) is
significantly shorter than that in Ph2Si(OCH2CH2)2NH (2.301 Å)
[4]. The N–Si coordination bond become shorter (by 0.505 Å) by
replacing one phenyl ligand in Ph2Si(OCH2CH2)2NMe (2.68 Å)
[12] with a fluorine atom.
Fig. 2. Molecular structure of 5. Atoms are presented by thermal ellipsoids with
50% probability. Hydrogen atoms are omitted for clarity.
It is noteworthy that N–Si distance in 3 is noticeably shorter
than in 1-fluorosilatrane [13] because of lower total electronega-
Fig. 1. Molecular structure of 3. Atoms are presented by thermal ellipsoids with 50% probability. Hydrogen atoms with exception of H1 are omitted for clarity.

610
A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
Fig. 3. Molecular structure of 9. Atoms are presented by thermal ellipsoids with 50% probability. Hydrogen atoms with exception of H1 are omitted for clarity.
The N1–Si1–F1 angles in compounds 5 and 9 are 171–172°
(Table 2) which are lower than in 1-fluorosilatrane (179.7°) [13].
The N1–Si1–F1 angle (178.4°) in compound 3 is close to the value
for 1-fluorosilatrane. Such a discrepancy in values of N1–Si1–F1
angles in compounds 3, 5 and 9 are related to the sterical repulsion
between equatorial substituent at Si1 atom and substituent at N1
atom. Indeed, the hydrogen atoms of Ph group at Si and Me group
at N atoms have short C5. . .H11C (2.73 Å) and H1A. . .H5A (2.28 Å)
contacts in the crystal structures of 5 and 9, respectively. The latter
values are less than sum of van der Waals radii of the correspond-
ing atoms [11]. Besides, the values of torsional angles C11–N1–Si1–
C5 in 5 (29.8°) and H1A–N1–Si1–C5 in 9 (21.6°) is additional proof
for repulsive character of above contacts. Thus, the short contacts
between substituents at Si1 and N1 atoms in 5 and 9 led to the dis-
tortion of geometry of Si1 atom coordination centre and weaken-
ing N–Si coordination bond. On the contrary, in 3 the H1. . .F2
contact may serve as additional factor for shortening Si–N distance
and almost ideal TBP geometry of Si1 atom coordination centre.
In all three compounds 3, 5 and 9 the silicon atom deviates from
the equatorial plane toward the axial F1 ligand, the displacement
of the silicon atom (DSi) being close to 0.1 Å (Table 2). Lesser DSi
value for 5 (0.14 Å) than that for Ph2Si(OCH2CH2)2NMe (0.38 Å)
[12] suggests strengthening the N ? Si coordination bond by
replacement of one phenyl group at silicon by an electron-with-
drawing fluoro ligand. The pentacoordination degree in
XPhSi(OCH2CH2)2NMe increases from 50% to 94% (TBPeq) on going
from X = Ph to X = F.
Table 2
Selected bond lengths (Å) and angles (°) in the crystal structures of 3, 5 and 9
3
5
9
PW91–PW
9
N1 ? Si1
Si1–F1
Si1–F2
Si1–O1
Si1–O2
Si1–C5
N1–C3
N1–C4
N1–R
N1–Si1–F1
O1–Si1–F1
O1–Si1–O2
O1–Si1–C5
O1–Si1–F2
O2–Si1–F2
O2–Si1–C5
1.981(6)
1.617(4)
1.595(5)
1.635(6)
1.628(5)
–
1.492(8)
1.480(9)
0.92
178.4(3)
93.0(3)
123.9(3)
–
117.5(4)
117.3(4)
–
2.1751(7)
1.6452(6)
–
2.0590(4)
1.6612(3)
–
1.6763(4)
1.6671(4)
1.8708(5)
1.4756(6)
1.4763(6)
0.90
170.99(2)
–
122.28(2)
119.29(2)
–
2.083
2.083
1.679
1.696
1.685
1.880
1.476
1.475
1.029
170.5
89.7
1.6562(6)
1.6569(7)
1.8680(9)
1.473(1)
1.483(1)
1.477(1)
171.98(3)
93.49(3)
124.01(4)
115.80(4)
–
122.5
118.0
119.0
–
–
118.30(4)
0.1367(4)
0.4473(8)
94
117.84(2)
0.0772 (3)
0.3550 (3)
98
D
D
%TBPe
Si
N
0.105(3)
0.446(4)
96
0.07
0.39
a
P
3
1
120ꢂ ꢀ3
ð
n¼1Un
a
Percent pentacoordinationð%TBPeqÞ ¼
Þ ꢃ 100.
U
n
are the angles
120ꢂ ꢀ109:5ꢂ
Req-Sil-Yeq [14].
tivity of the substituents at silicon in the latter in comparison with
quasisilatrane 3. The N–Si bond length in 3 is very close to that in
silatranyl oxonium salt [Me2OSi(OCH2CH2)3N] ꢁ BF4, the compound
with shortest N–Si distance in silatranes (1.965 Å) [15].
The axial Si1–F1 bond lengths in 3, 5 and 9 are longer (by 0.016,
0.044 and 0.059 Å, respectively) relative to that for equatorial Si1–
F2 bond in 3 (1.595 Å) which is close to typical Si–F bond distance
accepted for tetracoordinate silanes (1.601 Å) [11].
2.3. Chemical bonding in crystal of 5 and 9
Above X-ray data reveal the presence of the short and thus
strong N ? Si coordination bond in crystals of compounds 3, 5

A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
611
Table 3
Crystallographic parameters for 3, 5 and 9
3
5
9
Empirical formula
Formula weight
Crystal system
C4H9NO2F2Si
169.14
Monoclinic
0.7 ꢃ 0.1 ꢃ 0.1
1.613
6.338(2)
9.531(3)
6.511(2)
117.7(1)
348.3(3)
P21, 2
C11H16NO2FSi
241.34
Monoclinic
0.2 ꢃ 0.2 ꢃ 0.05
1.395
7.3149(4)
11.1975(6)
14.0314(8)
90.65(1)
1149.2(1)
P21/c, 4
C5H12NO2FSi
165.25
Orthorhombic
0.1 ꢃ 0.1 ꢃ 0.1
1.446
6.7543(3)
9.6468(5)
11.6465(5)
90.0
Crystal size (mm)
Density (calc.) (g cmꢀ3
a (Å)
)
b (Å)
c (Å)
b (°)
V (Å3)
758.8(1)
P212121, 4
108.72
Space group, Z
2hmax (°)
52.04
66.54
Scan type
Reflections collected
/ and x scans
14466
3116
62856
Independent reflections [R(int)
Number of reflections with I > 2r(I)
]
1328 (0.0609)
947
4400 (0.0251)
3842
9350 (0.0339)
7893
Parameters
111
3.15
0.809/0.969
0.964
146
2.03
0.961/0.990
1.049
92
2.69
0.974/0.974
1.039
Linear absorption (cmꢀ1
Tmin/Tmax
)
Goodness-of-fit (GOF)
R1 [I > 2
wR2 (all reflections)
Absolute structure parameter
max, e
r
(I)]
0.0678
0.1483
0.04(1)
ꢀ0.45/0.52
0.0303
0.0899
0.0293
0.0716
0.02(4)
ꢀ0.23/0.41
qmin
/
q
ꢀ0.29/0.46
and 9. However, the nature of chemical bonding cannot be verified
without detail knowledge of the electron structure of these mole-
cules which can be extracted from results of quantum chemical
calculations. Therefore we carried out the high resolution X-ray
diffraction study and the quantum chemical calculations of crystal
structure of compounds 5 and 9. Such type of quantum chemical
calculations in terms of DFT theory (PW91 exchange correlation
functional and plane wave (PW) basis set allowed one to minimize
the possible experimental errors in topological parameters and
compare the characteristics of N ? Si coordination bond depend-
ing on changes of Si1 and N1 atoms coordination environment.
The choice of PW91–PW method instead of standard B3LYP and
MP2 calculations of isolated molecules is caused by necessity to
take into account the crystal packing. The analysis of literature
concerning pentacoordinated silicon species has shown that inter-
atomic Si–N distances in isolated molecules [16–18] are in most
cases exceed the experimental values (revealed by X-ray diffrac-
tion) by 0.2–0.3 Å, that makes difficult direct comparison experi-
mental and theoretical results. Unfortunately, the disorder of C1
and C2 atoms in compound 3 made impossible the experimental
study and quantum chemistry calculation of its crystal structure.
Bond lengths and angles calculated by PW91–PW for structure
of compounds 5 and 9 are in good agreement with experimental
ones (Table 2). The main discrepancies (up to 0.03–0.1 Å) are ob-
served for weak intramolecular contacts H. . .H, C–H. . .O and
C–H. . .F. All bonds formed by Si atom are elongated in comparison
to experimental values by ca. 0.02 Å, so the precision of PW91–PW
calculations is better than that of hybrid functionals [16] and MP2
[17,18] in case of isolated molecules of silatranes.
are characterized by domination of potential energy density (Ve(r))
in CP(3,ꢀ1) (Ee(r) and
»
2q(r) < 0) and correspond to ordinary cova-
lent bonds such as C–C, N–C and C–O. In the case of domination of
»
kinetic energy density in CP(3,ꢀ1) (Ee(r) and ( 2q(r) > 0) inter-
atomic interactions correspond to closed shell type. The examples
of latter interactions are highly polar ionic bonds (Na–Cl, Li–F) as
well as weak intermolecular contacts. The third type of interatomic
interactions titled as ‘‘intermediate type” includes the bonds with
domination of potential energy density and positive sign of Lapla-
cian in CP(3,ꢀ1). Both in 1-methylsilatrane [20] and O,N-chelated
silicon difluoride [21] the N ? Si bond correspond to intermediate
type of interatomic interactions.
Topological analysis of theoretical and experimental
q(r) in
crystal structure of 5 and 9 has revealed the CPs(3,ꢀ1) in regions
of all chemical bonds including N ? Si bond (Table 4). Also, the
CPs(3,ꢀ1) correspond to weak intramolecular H. . .H, C–H. . .O and
C–H. . .F interactions as well as N–H. . .O and N–H. . .F bonds were
localized. All C–O, C–C and N–C bonds belong to shared (covalent)
type of interatomic interactions. All intermolecular interactions
correspond to the closed shell type. In CPs(3,ꢀ1) of the Si–O and
N ? Si coordination bonds the positive sign of »
2q(r) and negative
one of Ee(r) are observed (Table 4). To get further information on
the N ? Si bonding we estimated the experimental and theoretical
k1/k3 ratio values in 9 and 5 which are equal to 0.346, 0.304 and
0.227, respectively. These values can be considered as extent of
covalent character of the coordination bonds in hypervalent
organosilicon compounds [16,21]. The k1/k3 obtained fall within
the range typical for most of silatranes. Thus, according to AIM the-
ory we can conclude that N ? Si intramolecular bond in quasisi-
latranes corresponds to highly polar bond with pronounced ionic
contribution.
On the basis of experimental study and PW91–PW calculations
of crystal structures of 5 and 9 the electron density distribution
function (
was performed using topological analysis of experimental and cal-
culated (r) in terms of R.F. Bader’s ‘‘Atoms in molecules theory”
q
(r)) was obtained. Analysis of chemical bonding pattern
We analyzed the nature of chemical bonding in axial N1–Si1–F1
fragment on the basis of electron localization function (ELF [22])
distribution which is indicative for concentrations of valence elec-
tron density in regions of chemical bonds and positions of lone
electron pairs. The sections of experimental and theoretical
(PW91–PW) ELF in O1–Si1–F1 plane (Figs. 4 and 5) in 9 allowed
one to suggest that transfer of electron density from electron pair
of N1 to the region of Si1–F1 bond is rather small. Indeed, it can
be seen from the Figs. 4 and 5 that in 9 the electron density
q
(AIM) [19]. This approach was successfully utilized for combined
experimental and theoretical study of characteristics of the
N ? Si bonds in crystal structures of 1-methylsilatrane [20] and
O,N-chelated silicon difluoride [21].
According to AIM theory [19] the interatomic interactions di-
vided into three types. The first type titled as ‘‘shared interactions”

612
A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
Table 4
3. Experimental
Topological characteristics of bonds in Si1 atom coordination centre in structures of 5
and 9
3.1. General comments
Experiment
PW91–PW calculation
All reactions were carried out under an argon atmosphere. Stan-
dard precautions to avoid moisture were taken. Benzene and hex-
ane were purified by distillation from sodium. DMSO-d6 was kept
over 4A molecular sieves.
q
(r), e Åꢀ3
N1 ? Si1
Si1–F1
Si1–O1
Si1–O2
Si1–C5
0.53
0.99
1.02
1.06
0.83
0.41
0.98
1.08
1.07
0.94
0.52
0.94
1.02
1.05
0.93
The 1H, 13C, 19F and 29Si NMR spectra were recorded on a Bruc-
ker DPX-400 spectrometer (1H, 400,13 MHz; 13C, 100.62 MHz; 15N,
40.55 MHz; 19F, 376.50; 29Si, 79.50 MHz) at room temperature. 1H
and 13C chemical shifts were referenced to residual solvent reso-
nances, 19F chemical shifts to external CCl3F, and 29Si chemical
shifts to external Me4Si.
»
2 q(r), Åꢀ5
N1 ? Si1
Si1–F1
Si1–O1
Si1–O2
Si1–C5
2.24
10.78
7.18
9.33
1
1.21
22.45
20.24
19.76
2.47
2.44
20.86
18.61
18.98
1.76
Ee(r), Hartree Åꢀ3
N1 ? Si1
Si1–F1
Si1–O1
Si1–O2
Si1–C5
Ve(r), a.u. [Ebond, kcal/mol]
N1 ? Si1
Si1–F1
Si1–O1
Si1–O2
Si1–C5
3.2. X-Ray diffraction studies
ꢀ0.15
ꢀ0.41
ꢀ0.66
ꢀ0.66
ꢀ0.57
ꢀ0.15
ꢀ0.25
ꢀ0.44
ꢀ0.44
ꢀ0.67
ꢀ0.21
ꢀ0.23
ꢀ0.4
X-Ray diffraction measurements for 3, 5 and 9 were carried out
ꢀ0.43
ꢀ0.67
with a Bruker Smart APEX II diffractometer at 100 K using Mo K
radiation (graphite monochromator, k[Mo K ] = 0.71073 Å). The
frames were integrated and corrected for absorption by the APEX
a
a
2
ꢀ0.09 [28.4]
ꢀ0.058 [18.1]
ꢀ0.308 [96.7]
0.339 [106.3]
ꢀ0.336 [105.3]
ꢀ0.222 [69.6]
ꢀ0.088 [27.7]
ꢀ0.286[89.6]
ꢀ0.311 [97.4]
ꢀ0.323 [101.2]
ꢀ0.217 [67.9]
program suite [25]. Structures were solved by direct methods
and non-hydrogen atoms were refined in full-matrix anisotropic
approximation. The hydrogen atoms were located from differential
Fourier synthesis of the electron density and refined isotropically
in rigid body approximation. All calculations were carried out
using the SHELXTL 5.1 program package [26]. Details of crystallo-
graphic data and experimental conditions are presented in Table 3.
The analytical form of the electron density distribution function
in 9 was obtained by a multipole refinement based on Hansen–
Coppens [27] formalism using XD program package [28]. Prior to
refinement procedure all C–H bonds were normalized to values
corresponding to values obtained in neutron diffraction experi-
ments (1.08 Å [29]) while for N–H bond the value 1.03 Å were as-
sumed on the basis of quantum chemical calculations. The level of
the multipole expansion was octadecapole for C, O, N, Si, F atoms
and dipole for hydrogens. The scattering factor of the hydrogen
atoms was calculated from the contracted radial density functions
ꢀ0.273 [85.4]
ꢀ0.271 [85.3]
ꢀ0.318 [91.9]
ꢀ0.178 [56.0]
Bond energies calculated according to ELM scheme [23] are given in square
brackets.
maximum in region of N ? Si coordination bond is localized at
0.7 Å from N1 atom.
The N ? Si bond energy has been estimated semi-qualitatively
using correlation formula (ELM) [23]
Ebond ꢄ ꢀ1=2VeðrÞ½a:u:ꢅ
One can see that experimental values are systematically decreased
in comparison with theoretical ones. Comparison of obtained values
of Ebond for 9 (Table 4) with literature data have shown that they are
not exceed 1/3 of energy of ‘‘normal” N–Si bond in (Me3Si)2NH
(75.8 kcal molꢀ1 [24]).
The electron-acceptor effect of substituents at Si1 atom was
analyzed on the basis of atomic charges (AIM charges, Table 5) cal-
culated for each type of atoms as difference between atomic num-
ber and population of respective atomic basin. These charges have
physical meaning and they are transferable between molecules
with same molecular fragments.
(j = 1.2). The refinement was carried out against F with usage of C2
symmetry for the Si1 and N1 atoms. For hydrogens a cylindrical
symmetry was assumed. The refinement is converged to
R = 0.0176, Rw = 0.0135 and GOF = 1.228 for 3854 merged reflec-
tions with I > 3r(I) and Fobs > 1.7. All bonded pairs of atoms satisfy
the Hirshfeld rigid-bond criteria (the maximum difference of the
mean square displacement amplitudes was 6 ꢃ 10ꢀ4 Å2). The resid-
ual electron density was not more than 0.225 e Åꢀ3. Topological
analysis of the experimental
q(r) function was carried out using
It can be seen from Table 5 that Si1 is characterized by positive
charge while N, O and F atoms are negatively charged. The exper-
imental and calculated values of AIM charges are in good agree-
ment with exception for N1 atom. The high negative charge of
FCSiO2 moiety (experimental and calculated values 1.21 and 1.09
e, for 9 and 5, respectively) is indicative for significant Lewis acid-
ity of this fragment.
the WINXPRO program package [30].
3.3. Details of quantum chemical calculations
The quantum chemical calculations of structure 9 in the crystal
were carried out using the VASP 4.6.31 code [31]. Conjugated gra-
dient technique was used for optimizations of the atomic positions
(started from experimental data) and minimization of total energy.
Projected augmented wave (PAW) method was applied to account
for core electrons while valence electrons were approximated by
plane-wave expansion with 680 eV cutoffs. Exchange and correla-
tion terms of total energy were described by PW91 [32] exchange-
correlation functional. Kohn–Sham equations were integrated with
8 irreducible k-points. Using DFT method was not possible owing
to dispersion interactions. For this reason calculated cell parame-
ters may be systematically overestimated or underestimated up
to 5%. Thus, the experimental values of cell parameters were used
in the calculations. At a final step of our calculations atomic
2.4. Conclusion
In summary the synthesis of quasisilatranes with electron
acceptor substituents at Si atom without noticeable sterical over-
crowding is the fruitful approach for preparation of compounds
with strong N ? Si bond. It has been shown that the strength of
the N ? Si coordination is strongly dependent on the number of
fluorine ligands at silicon. Detailed study of electron density distri-
bution function reveals that the energy of N ? Si bond in quasisi-
latrane 9 is about 1/3 of normal N–Si bond.

A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
613
Fig. 4. The section of experimental electron localization functions in O1Si1F1 plane in 9. Isolines of ELF (g > 0.5) corresponding to concentrations of valence electron density
are drawn by solid lines.
displacements converged were better than 0.01 eV Åꢀ1, as well as
energy variations were less than 10ꢀ3 eV. In order to carry out
the topological analysis of electron density distribution function
in terms of AIM theory the dense FFT (fast Fourier transformation)
grid was used (corresponding to cutoff 1360 eV). The latter was ob-
tained by separate single point calculation of optimized geometry
with hard PAWs for each atom type. The topological analysis of
electron density distribution function was carried out using AIM
program – part of ABINIT software package [33].
0.5 h at ꢀ5–0 °C. Filtration of a solid product followed by sublima-
tion in vacuum gave 3 (1.39 g, 47%), m.p. 180 °C. Anal. Calc. for
C4H9NO2F2Si: C, 28.01; H, 5.73; N, 8.39; F, 22.12. Found: C, 28.39;
H, 5.36; N, 8.28; F, 22.46%. 1H NMR (DMSO-d6): d 2.71, 2.91 (dt,
2H, NCH2, 3J = 6.1, JAB = 11.6 Hz); 3.61, 3.72 (dt, 2H, OCH2,
JAB = 10.2 Hz). 13C NMR (DMSO-d6): d 43.63 (NCH2); 57.71 (OCH2,
3
d, JCF = 4.6 Hz). 29Si NMR (DMSO-d6): d ꢀ113.4 dd. 19F NMR
2
(DMSO-d6):
d
ꢀ136.1 (F), ꢀ137.9 (F0) JSi—F ¼ 192:4 Hz, JFF
=
0
23.5 Hz, JSi–F = 132.2 Hz. 15N NMR (DMSO-d6): d ꢀ348.0.
3.4. Synthesis of quasisilatranes
3.4.2. From organylfluorosilanes: general procedure
3.4.2.1. 1-Phenyl-1-fluoro-5-methylquasisilatrane (5).
3.4.1. From SiF4. 1,1-Difluoroquasisilatrane (3)
(a) Phenyltrifluorosilane 1 (12.17 g, 0.07 mol) was added to a solu-
tion of (HOCH2CH2)2NMe (8.96 g, 0.07 mol) in C6H6 (10 ml). After
stirring for 30 min at ꢀ3–0 °C, the precipitate was filtered, recrys-
tallized from DMF and dried under vacuum to yield 5 (3.51 g, 71%)
Gaseous SiF4 (prepared from 37.82 g, 0.02 mol Na2SiF6 and
19.6 g, 0.02 mol conc. H2SO4) was passed through a solution of
(Me3SiOCH2CH2)2NH (4.36 g, 0.02 mol) in hexane (10 ml) for

614
A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
Fig. 5. The section of theoretical electron localization functions in O1Si1N1 plane in 9. Isolines of ELF (g > 0.5) corresponding to concentrations of valence electron density are
drawn by solid lines.
2.65, 2.74 (dt, 2H, NCH2, JAB = 12.4, 3J = 6.04 Hz); 3.95, 4.01 (dt,
2H, OCH2, JAB = 12.1 Hz). 13C NMR (DMSO-d6): d 42.95 (NMe);
54.10 (NCH2); 59.83 (OCH2); 127.93 (Co), 128.96 (Cp), 131.86
(Cm), 134.05 (Ci). 29Si NMR (DMSO-d6): d ꢀ80.3, JSi–F = 214.3 Hz.
15N NMR (DMSO-d6): d ꢀ345.6.
Table 5
Atomic charges in terms of AIM theory for selected atoms in crystal of 5 and 9
Experiment
PW91–PW calculation
9
5
9
Si1
N1
F1
O1
O2
C5
R
2.46
ꢀ0.82
ꢀ0.67
ꢀ1.09
ꢀ1.14
ꢀ0.68
0.38
2.70
ꢀ1.07
ꢀ0.85
ꢀ1.26
ꢀ1.25
ꢀ0.56
0.37
2.69
(b) Compound
5 (14.88 g, 40%) was also obtained from
ꢀ0.84
ꢀ0.85
ꢀ1.25
ꢀ1.26
ꢀ0.54
0.42
(Me3SiOCH2CH2)2NMe (16.24 g, 0.06 mol) and PhSiF3 (10.00 g,
0.06 mol).
3.4.2.2. 1,1-Diphenyl-5-methylquasisilatrane (7). The compound 7
(1.14 g, 53%) was obtained from Ph2SiF2 (6) in benzene (10 ml)
using the above procedures and the same initial diethanolamine
derivatives (Section 3.4.2.1. (a) and (b)). B.p. 180–182 °C/2 mmHg,
m.p. 61 °C. 1H NMR (DMSO-d6): d 1.69 (s, 3H, NMe); 2.65 (t, 4H,
NCH2, 3J = 4.8 Hz); 4.05 (t, 4H, OCH2); 7.34, 7.65 (m, 10H, Ph). 13C
NMR (DMSO-d6): d 42.28 (NMe); 55.60 (NCH2); 61.51 (OCH2);
C3
C4
0.08
0.15
0.34
0.33
0.36
0.34
as white crystals, m.p. 84 °C. Anal. Calc. for C11H16NO2FSi: C, 54.74;
H, 6.68; N, 5.80; F, 7.87. Found: C, 54.51; H, 6.89; N, 6.01; F, 7.62%.
1H NMR (DMSO-d6): d 1.67 (s, 3H, NMe); 7.32, 7.51 (m, 5H, Ph);

A.A. Korlyukov et al. / Journal of Organometallic Chemistry 694 (2009) 607–615
615
127.64 (Co), 128.63 (Cp), 133.51 (Cm), 138.49 (Ci). 29Si NMR (DMSO-
d6): d ꢀ44.0.
(b) M.G. Voronkov, V.A. Pestunovich, E.E. Liepin’sh, S.N. Tandura, G.I. Zelchan,
E.Ya. Lukevics, Izv. Akad. Nauk Latv. SSR, Ser. Khim. (1978) 114.
[4] J.J. Daly, F. Sanz, J. Chem. Soc., Dalton Trans. (1974) 2051.
[5] R. Krebs, D. Schomburg, R. Schmutzler, Z. Naturforsch. 40b (1985) 282.
[6] M.G. Voronkov, E.A. Grebneva, O.M. Trofimova, N.F. Chernov, A.I. Albanov, N.N.
Chipanina, Dokl. Chem. 409 (2006) 779.
[7] M.G. Voronkov, A.I. Albanov, E.A. Grebneva, O.M. Trofimova, N.F. Chernov, N.N.
Chipanina, Russ. J. Gen. Chem. 76 (2006) 1942.
[8] (a) B.R. Piekos, R. Sujecki, M. Sankowski, Z. Anorg. Allg. Chem. 454 (1979) 187;
(b) J.Y. Corey, N.P. Rath, Ch.S. John, E.R. Corey, J. Organomet. Chem. 399 (1990)
221.
[9] W. Ziche, B. Ziemer, P. John, J. Weis, N. Auner, J. Organomet. Chem. 521 (1996)
29.
[10] V.A. Pestunovich, B.Z. Shterenberg, S.N. Tandura, V.P. Baryshok, E.I. Brodskaya,
N.G. Komalenkova, M.G. Voronkov, Dokl. Akad. Nauk SSSR 264 (1982) 632.
[11] A. Kemme, J. Bleidelis, I. Urtane, G. Zelchan, E. Lukevics, J. Organomet. Chem.
202 (1980) 115.
3.4.2.3. 1-Methyl-1-fluoroquasisilatrane (9). The compound 9 was
obtained from MePhSiF2 (11.87 g, 0.07 mol) and (HOCH2CH2)2NH
(7.89 g, 0.07 mol) in benzene (10 ml) by procedure mentioned in
Section 3.4.2.1. (a). Yield 45% (6.9 g), white crystals, m.p. 60–
61 °C (from C6H6). Anal. Calc. for C5H12NO2FSi: C, 36.34; H, 7.27;
N, 8.48; F, 11.51. Found: C, 36.61; H, 7.20; N, 8.13; F, 11.83%. 1H
3
NMR (DMSO-d6): d 0.06 (d, 3H, SiMe, JHF = 6.85 Hz); 2.54, 2.87
3
(ddt, 2H, NCH2, JAB = 12.0, 3J = 5.6, JHNCH = 5.9 Hz); 3.53, 3.69 (dt,
2H, OCH2, JAB = 10.3 Hz). 13C NMR (DMSO-d6): d 0.73 (d, SiMe,
3
2JCF = 45.5); 43.94 (NCH2); 58.51 (d, OCH2, JCF = 3.4 Hz). 29Si NMR
ꢀ82.1. 19F NMR (DMSO-d6):
d
ꢀ107.4,
[12] A. Bondi, J. Phys. Chem. 68 (1964) 441.
(DMSO-d6):
d
[13] L. Párkányi, P. Hencsei, L. Bihátsi, T. Müller, J. Organomet. Chem. 269 (1984) 1.
[14] K. Tamao, T. Hayashi, Y. Ito, Organometallics 11 (1992) 2099.
[15] R.J. Garant, L.M. Daniels, S.K. Das, M.N. Janakiraman, R.A. Jacobson, J.G.
Verkade, J. Am. Chem. Soc. 113 (1991) 5728.
[16] M.V. Zabalov, S.S. Karlov, G.S. Zaitseva, D.A. Lemenovskii, Russ. Chem. Bull.
(2006) 464.
[17] J.M. Anglada, C. Bo, J.M. Bofill, R. Crehuet, J.M. Poblet, Organometallics 18
(1999) 5584.
[18] J. Kobayashi, K. Goto, T. Kawashima, M.W. Schmidt, S. Nagase, J. Am. Chem.
Soc. 124 (2002) 3703.
JSi–F = 209.9 Hz. 15N NMR (DMSO-d6): d ꢀ343.0.
Acknowledgment
We thank the Found of President of Russian Federation (Science
Schools’ Grant – 255.2008.3) for financial support.
Appendix A. Supplementary material
[19] R.F.W. Bader, Atoms in Molecules.
Oxford, UK, 1990.
A Quantum Theory, Clarendron Press,
[20] A.A. Korlyukov, K.A. Lyssenko, M.Yu. Antipin, V.N. Kirin, E.A. Chernyshev, S.P.
Knyazev, Inorg. Chem. 41 (2002) 5043.
[21] N. Kocher, J. Henn, B. Gostevskii, D. Kost, I. Kalikhman, B. Engels, D. Stalke, J.
Am. Chem. Soc. 126 (2004) 5563.
[22] A.D. Becke, K.E. Edgecombe, J. Chem. Phys. 92 (1990) 5397.
[23] E. Espinosa, E. Molins, C. Lecomte, Chem. Phys. Lett. 285 (1998) 170.
[24] A.E. Beezer, C.T. Mortimer, J. Chem. Soc. A (1966) 514.
[25] APEX2 Software Package, Bruker AXS Inc., 5465, East Cheryl Parkway, Madison,
WI 5317.
CCDC 688265, 675484 and 688266 contains the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2008.09.010.
[26] G.M. Sheldrick, SHELXTL-97, 5.10, Bruker AXS Inc., Madison, WI-53719, USA,
1997.
References
[27] N.K. Hansen, P. Coppens, Acta Crystallogr. A 34 (1978) 909.
[28] A. Volkov, P. Macchi, L.J. Farrugia, C. Gatti, P. Mallinson, T. Richter, T.
[1] (a) M.G. Voronkov, V.M. D’yakov, Silatranes, Nauka, Novosibirsk, 1978. pp. 1–
208;
Koritsanszky, XD2006
– A computer program package for multipole
(b) M.G. Voronkov, V.M. D’yakov, S.V. Kirpichenko, J. Organomet. Chem. 233
(1982) 1;
refinement, topological analysis of charge densities and evaluation of
intermolecular energies from experimental and theoretical structure factors,
2006.
(c) C. Chuit, R.J.P. Corriu, C. Reye, J.C. Young, Chem. Rev. 93 (1993) 1371;
(d) J.G. Verkade, Coord. Chem. Rev. 137 (1994) 233;
(e) V. Pestunovich, S. Kirpichenko, M. Voronkov, in: Z. Rappoport, Y. Apeloig
(Eds.), The Chemistry of Organic Silicon Compounds, vol. 2, Wiley, Chichester,
1998. pp. 1447–1537.
[29] F.H. Allen, O. Kennard, D.G. Watson, L. Brammer, A.G. Orpen, R. Taylor, J. Chem.
Soc., Perkin Trans. II (1987) S1–S19.
[30] A. Stash, V. Tsirelson, WINXPRO, A program for calculation of the crystal and
molecular properties using the model electron density, 2001;
A. Stash, V.G. Tsirelson, Acta Crystallogr. A 35 (2002) 371.
[31] (a) G. Kresse, J. Hafner, Phys. Rev. B 47 (1993) 558;
(b) G. Kresse, Thesis, Technische Universitat Wien, 1993.;
(c) G. Kresse, J. Furthmüller, Comput. Mater. Sci. 6 (1996) 15;
(d) G. Kresse, J. Furthmüller, Phys. Rev. B 54 (1996) 11169.
[32] J.P. Perdew, Y. Wang, Phys. Rev. B 45 (1992) 13244.
[2] (a) I.P. Urtane, G.I. Zelchan, E. Lukevics, Z. Anorg. Allg. Chem. 520 (1985) 179;
(b) V.M. D’yakov, G.I. Orlov, Medium nitrogen containing silacyclanes,
NIITEKhim, Moscow, 1985. pp. 1–60;
(c) I.S. Birgele, A.A. Kemme, E.L. Kupche, E.E. Liepin’sh, I.B. Mazeika, V.D. Shats,
in: E.Ya. Lukevics (Ed.), Organosilicon Derivatives of Alkanolamines, Zinatne,
Riga, 1987, pp. 1–230;
(d) A.A. Selina, S.S. Karlov, G.S. Zaitseva, Khim. Geterotsikl. Soedin. (2006)
1777.
[3] (a) V.P. Davydova, M.G. Voronkov, B.N. Dolgov, in: Chemistry and Practical Use
of Organosilicon Compounds. Abstracts of Conference on Organosilicon
Monomers, Leningrad, CBTI, vol. 1, 1958, p. 204;
[33] X. Gonze, J.-M. Beuken, R. Caracas, F. Detraux, M. Fuchs, G.-M. Rignanese, L.
Sindic, M. Verstraete, G. Zerah, F. Jollet, M. Torrent, A. Roy, M. Mikami, Ph.
Ghosez, J.-Y. Raty, D.C. Allan, Comput. Mater. Sci. 25 (2002) 478.