Synthesis, molecular and crystal structures, and characteristic features of electronic structures of salicylamide-based B,Si-containing chelates

Article abstract of DOI:10.1007/s11172-005-0050-9

The reaction of 4-(2-hydroxybenzoyl)-2,2,6,6-tetramethyl-2,6- disilamorpholine with BF₃·Et₂O afforded (O-B)-chelate 4-[2-(difluoroboroxy)benzoyl]-2,2,6,6-tetramethyl-2,6- disilamorpholine. Treatment of the latter with BF₃·

Full text of DOI:10.1007/s11172-005-0050-9

1
924
Russian Chemical Bulletin, International Edition, Vol. 53, No. 9, pp. 1924—1931, September, 2004
Synthesis, molecular and crystal structures, and characteristic features of
electronic structures of salicylamideꢀbased B,Siꢀcontaining chelates
aꢀ
a
a
b
b
A. A. Korlyukov, K. A. Lyssenko, M. Yu. Antipin, A. G. Shipov, O. A. Zamyshlyaeva,
b
b
c
c
b
E. P. Kramarova, Vad. V. Negrebetsky, S. A. Pogozhikh, Yu. E. Ovchinnikov, and Yu. I. Baukov
aA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
2
8 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 5085. Eꢀmail: alex@xrlab.ineos.ac.ru
b
Russian State Medical University
1
ul. Ostrovityanova, 117997 Moscow, Russian Federation.
Fax: +7 (095) 434 0329. Eꢀmail: baukov.rgmu@mtuꢀnet.ru
c
Novosibirsk State Pedagogical University,
2
8 ul. Vilyuiskaya, 630126, Novosibirsk, Russian Federation.
Eꢀmail: ovchin@hotmail.ru
The reaction of 4ꢀ(2ꢀhydroxybenzoyl)ꢀ2,2,6,6ꢀtetramethylꢀ2,6ꢀdisilamorpholine with
BF •Et O afforded (O—B)ꢀchelate 4ꢀ[2ꢀ(difluoroboroxy)benzoyl]ꢀ2,2,6,6ꢀtetramethylꢀ2,6ꢀ
3
2
disilamorpholine. Treatment of the latter with BF •Et O or SOCl gave rise to products of the
3
2
2
disilamorpholine ring opening, viz., (O—B)ꢀchelate 2ꢀ(difluoroboroxy)ꢀN,Nꢀbis(dimethylꢀ
fluorosilylmethyl)benzamide or 2ꢀ(difluoroboroxy)ꢀN,Nꢀbis(dimethylchlorosilylmethyl)benzꢀ
amide, respectively. The structures of the compounds synthesized were confirmed by Xꢀray
1
13
29
diffraction analysis and H, C, and Si NMR spectroscopy. Highꢀprecision Xꢀray diffraction
study and quantumꢀchemical calculations demonstrated that the coordination O→Si bond is
absent in the two lastꢀmentioned compounds.
Key words: 2,6ꢀdisilamorpholines, pentacoordinate silicon compounds, tetracoordinate
boron compounds, Xꢀray diffraction study, electron density distribution, quantumꢀchemical
calculations.
Earlier, a broad scope of the synthesis of silaoxaazaꢀ
fluoride 2 and 4ꢀ(2ꢀhydroxybenzoyl)ꢀ2,2,6,6ꢀtetramethylꢀ
2,6ꢀdisilamorpholine (3).
and siladiazaheterocycles with the use of unsubstituted and
functionally substituted carboxamides and chloro(chloroꢀ
methyl)dimethylsilane as a cyclosilylating reagent has been
exemplified by the preparation of sixꢀmembered 1ꢀoxaꢀ4ꢀ
As part of our investigation, we
synthesized B,Siꢀcontaining cheꢀ
lates starting from disilamorphoꢀ
line 3 and established the molecuꢀ
lar and crystal structures of these
chelates by Xꢀray diffraction
analysis.
azaꢀ2ꢀsilacyclanes,1
—3
4ꢀacylꢀ2,6ꢀdisilamorpholines,
1,4
5
and 4ꢀacylꢀ2,6ꢀdisilapiperazines. The formation of the
target products was demonstrated1 to proceed through
intermediate pentacoordinate silicon compounds, which
are more reactive in nucleophilic substitution reactions
—5
Under rather mild conditions,
the reaction of disilamorphoꢀ
6
than the corresponding tetrahedral silicon derivatives and
can be synthesized also by the reactions of silacyclanes
with electrophilic reagents.
line 3 with BF •Et O afforded
(O—B)ꢀchelate, viz., 4ꢀ[2ꢀ(diꢀ
X = Cl (1), F (2)
3
2
7
In the case of salicylamide and Nꢀmethylsalicylamide,
analogous cyclosilylation reactions with the use of the
hexamethyldisilazane—chloro(chloromethyl)dimethylꢀ
silane system afforded 1ꢀoxaꢀ4ꢀazaꢀ2ꢀsilabenzocycloꢀ
fluoroboroxy)benzoyl]ꢀ2,2,6,6ꢀtetramethylꢀ2,6ꢀdisilaꢀ
morpholine (4). Its structure was established by elꢀ
emental analysis, spectroscopy, and Xꢀray diffraction
analysis.
It should be noted that the (2ꢀhydroxybenzoyl)acetꢀ
amide derivative, which bears an analogous boronꢀconꢀ
8
,9
heptanꢀ5ꢀone derivatives.
In particular, this method
was used for the preparation of (O—B)ꢀchelate 4ꢀ(chloroꢀ
dimethylsilylmethyl)ꢀ2,2ꢀdimethylꢀ1ꢀoxaꢀ4ꢀazaꢀ2ꢀsilaꢀ
benzocycloheptanꢀ5ꢀone (1) from salicylamide. Comꢀ
pound 1 was used for the synthesis of the corresponding
taining fragment with a chelate ring involving the OBF O
2
1
0
group, has been used earlier in the synthesis of 2ꢀaminoꢀ
chromones.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1846—1853, September, 2004.
066ꢀ5285/04/5309ꢀ1924 © 2004 Springer Science+Business Media, Inc.
1

Salicylamideꢀbased B,Siꢀcontaining chelates
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
1925
The H, 13C, and 29Si NMR spectra of compounds 4,
1
5
, and 6 are consistent with the proposed structures. These
spectra show double sets of signals of the CH N and SiMe
2
2
groups. The lowꢀfield positions of the signals in the
2
9
Si NMR spectra of compounds 5 and 6 (δSi ~19—28,
see the Experimental section) are indicative of the abꢀ
sence of the intramolecular O→Si interaction in the liquid
phase. For example, the signals for the silicon atoms in
The reaction (1) was accompanied by the disilaꢀ
morpholine ring opening to give 2ꢀ(difluoroboroxy)ꢀN,Nꢀ
bis(dimethylfluorosilylmethyl)benzamide (5) containing
the (O—B)ꢀchelate fragment as a byꢀproduct. An increase
in the amount of BF •Et O and more drastic reaction
(
O—Si)ꢀchelate N,Nꢀbis(fluorodimethylsilylmethyl)acetꢀ
amide MeC(O)N(CH SiMe F) are observed at δ –23.5
2
2
2
Si
V
IV 7
(
Si ) and 29.0 (Si ). Hence, the spectral patterns of
3
2
compounds 4, 5, and 6 may be associated with hindered
amide rotation in the molecules of these compounds. Earꢀ
lier, this effect has been observed for Nꢀacylated 2,6ꢀdiꢀ
conditions facilitate the formation of tetrafluoride 5 as
the major product. Apparently, this is attributable to two
successive processes, viz., boronation at the hydroxy group
to form (O—B)ꢀchelate 4 (reaction (1)) followed by the
disilamorpholine ring opening in chelate 4 giving rise to
the final tetrafluoride 5 (reaction (2)). The latter reaction
was carried out separately. However, the possibility of
boronation, ring opening, and transboronation at the oxyꢀ
gen atom in the presence of BF •Et O occurring as comꢀ
1
5
silamorpholines and ꢀpiperazines.
Xꢀray diffraction study of compounds 4, 5, and 6. Reꢀ
lated compounds 4, 5, and 6 contain the following identiꢀ
cal or analogous molecular fragments: the bicyclic fragꢀ
ment A and the —CH SiMe X(1) groups (B and C, where
2
2
X(1) = F(1) or Cl(1)). These fragments are linked by the
planarꢀcoordinated N(1) atom (Figs 1 and 2). Therefore,
the overall conformations of the molecules can be deꢀ
scribed by several torsion angles listed in Table 1. Molꢀ
ecule 4 is more rigid than analogs 5 and 6, because the
groups B and C in 4 are involved in the sixꢀmembered
oxaazadisilinane ring. In all three compounds, the bicyꢀ
clic fragments A adopt virtually identical conformations,
as evidenced by the corresponding torsion angles ψ and ψ
3
2
petitive reactions cannot be ruled out.
7
8
(
see Table 1). The sixꢀmembered boronꢀcontaining ring
adopts a sofa conformation with the boron atom deviating
from the C(7)C(8)C(9)O(2) plane (planar within 0.03 Å)
by 0.80, 0.76, and 0.78 Å in molecules 4, 5, and 6, respecꢀ
tively. In these molecules, the torsion angles ψ and ψ ,
It should be noted that only the Si—F bonds in tetraꢀ
fluoride 5 are subjected to hydrolysis under mild condiꢀ
tions to give the starting disilamorpholine, viz., diꢀ
fluoride 4.
1
2
which determine the twist of the planes of the substituents
at the N(1) atom with respect to the plane of the bicyclic
fragment, have also nearly equal values, analogs 5 and 6
being characterized by the smallest differences in these
angles. The groups B and C in molecules 5 and 6 are
highly labile, due to which the threeꢀdimensional strucꢀ
ture of 5 differs from that of analog 6. The orientations of
the group C with respect to the plane of the substituents at
the N(1) atom and the plane of the bicyclic fragment A in
compound 5 are similar to those in 6 (difference in the
The direct reaction of disilamorpholine 3 with an exꢀ
cess of BF •Et O also affords tetrafluoride 5. The diꢀ
3
2
silamorpholine ring opening in difluoride 4 with retention
of the (O—B)ꢀchelate fragment occurs also in the reacꢀ
tion with thionyl chloride to give a dichloro analog of
tetrafluoride 5, viz., (O—B)ꢀchelate 2ꢀ(difluoroboroxy)ꢀ
N,Nꢀbis(chlorodimethylsilylmethyl)benzamide (6) (reacꢀ
tion (3)). The results of Xꢀray diffraction study of comꢀ
pounds 5 and 6 provide evidence for an interaction beꢀ
tween one of the silicon atoms and the oxygen atom of the
amide fragment, which is already involved in the donorꢀ
acceptor bond with the boron atom. The nature of this
interaction is discussed below.
angle ψ in these molecules is 13°). The orientations of
4
the Me X(2)Si(2) fragment relative to the NCSi(2) plane
2
(rotation about the C—Si bond) in 5 and 6 differ by 27°
(angles ψ ). Let us mention the factors, which could inꢀ
6

1
926
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
Korlyukov et al.
F(1)
F(2)
a
A
a
B(1)
O(3)
O(2)
C(9)
C(5)
C(4)
C(10)
B
C(7)
C(8)
N(1)
C(6)
Si(2)
C(11)
C(3)
B(1)
Si(1)
C(12) C(13)
O(1)
C(1)
Cl(1)
O(1)
C(5)
Si(1)
b
C
C(2)
C(2)
A
O(2)
F(3)
b
C(10)
C(9)
B(1)
O(1)
C(1)
C(11)
Si(1)
C(2)
O(1)
F(4)
B(1)
Si(1)
C(8)
Cl(1)
C(7)
F(1)
C(12)
C(13)
C(5)
N(1)
C
B
c
C(6)
F(2)
F(1)
Si(2)
C(4)
C(1)
C(3)
c
F(2)
B(1)
C(1)
A
O(2)
O(1)
Si(1)
O(1)
C(13)
C(12)
C(11)
Cl(1)
Si(1)
Cl(1)
C(2)
Fig. 2. Experimental deformation electron density (DED). Secꢀ
tions through the O(1)Si(1)C plane and the plane involving the
C=C(5), C(2), and C(1) atoms. Positive contours (electron denꢀ
sity accumulation) are solid, and negative contours (electron
density depletion) are dashed. The maps are contoured at
C(7)
C(8)
C(5)
N(1)
C(6)
B
C(9)
C(10)
C
0
.05 е Å–3 intervals.
Si(2)
Cl(2)
fluence the conformation of the fragment C in molecules 5
and 6. In compound 5, the observed conformation of
the group C is, apparently, determined by the short
F(2)...H(13)C(13) contact (2.25 Å). In molecule 6, the
corresponding Cl(2)...H(3)C(9) distance is 3.2 Å, i.e., it
is noticeably larger than the sum of the van der Waals radii
C(3)
C(4)
Fig. 1. Overall views of molecules 4 (а), 5 (b), and 6 (c) with
thermal ellipsoids drawn at the 50% probability level. The hydroꢀ
gen atoms are omitted.
1
1
of the H and Cl atoms (3.0 Å). Therefore, the conforꢀ

Salicylamideꢀbased B,Siꢀcontaining chelates
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
1927
Table 1. Torsion angles (ψ) characterizing the conformations of
molecules 4, 5, and 6
the overall configuration of the fragment being similar in
both molecules (deviations of the Si(1) atom are 1.44 and
–
1.36 Å, respectively). In both molecules, the Si(1)...O(1)
Angle
ψ/deg
distance is smaller than the sum of the van der Waals radii
1
1
of these atoms (3.5 Å) by more than 0.5 Å. The average
value of the C—Si—C bond angles is 113.9° (in the
groups C, the corresponding average angle is 111.3°). The
F(1) and Cl(1) atoms are in the vicinity of the Si(1)...O(1)
line; the O...Si—X angles are larger than 160° (Tables 2
and 3). In addition, the Si—X bonds in the groups B are
elongated, although insignificantly, compared to the
analogous bonds in the groups C. The aboveꢀmentioned
characteristic features are indicative of the occurrence of
a weak O...Si interaction in molecules 5 and 6.
The geometric parameters of the slightly distorted
trigonalꢀbipyramidal environment about the Si(1) atoms
in the structures of 5 and 6, viz., the Si(1)...O(1) distances
and the deviations ∆Ω of the solid angle formed by the
equatorial Si—C bonds of the Si(1) atoms from 2π (latꢀ
ter value corresponds to the symmetrical hypervalent
O—Si—Hal bond), agree well with the empirical relationꢀ
ship between these parameters revealed for pentacoorꢀ
4
5
6
O(1)—C(7)—N(1)—C(5) (ψ1)
O(2)—C(7)—N(1)—C(6) (ψ1)
O(1)—C(7)—N(1)—C(6) (ψ2)
O(2)—C(7)—N(1)—C(5) (ψ2) 177.9
C(7)—N(1)—C(5)—Si(1) (ψ3)
C(7)—N(1)—C(6)—Si(2) (ψ4)
N(1)—C(5)—Si(1)—F(1) (ψ5)
N(1)—C(5)—Si(1)—Cl(1) (ψ5)
N(1)—C(6)—Si(2)—F(2) (ψ6)
N(1)—C(6)—Si(2)—Cl(2) (ψ6)
—
0.3
—
–5.4
—
166.8
—
61.9
111.8
130.8
—
–54.3
—
–6.4
—
157.0
—
–48.6
122.7
—
–139.9
—
–28.7
—
–22.4
5.4
—
—
—
—
—
—
C(9)—C(8)—C(7)—O(1) (ψ7) –28.4
C(13)—C(8)—C(7)—O(1) (ψ7)
C(8)—C(7)—O(1)—B(1) (ψ8)
C(8)—C(7)—O(2)—B(1) (ψ8)
–25.3
—
12.1
—
—
—
9.6
—
mation of this moiety in the molecules depends substanꢀ
tially on intermolecular interactions.
The arrangement of the groups B in molecules 5 and 6
differs from that of the groups C. In molecules 5 and 6,
the Si(1) atoms deviate in opposite directions from the
1
2
dinate silicon compounds.
This type of interactions for twoꢀcoordinate O atoms
was observed for the first time. However, it is known that
these atoms can be additionally coordinated by various
O(1)C(7)N(1)C(5) plane (torsion angles ψ , see Table 1),
3
Table 2. Selected bond lengths and bond angles in molecules 4, 5 (X = F), and 6 (X = Cl)
Parameter
Crystal
Isolated molecule
(
MPW1PW91/6ꢀ311G(d) calculations)
4
5
6
5
6
Bond
d/Å
2.831(1)
2.084(1)
2.0629(9)
1.521(2)
—
Si(1)...O(1)
Si(1)—X(1)
Si(1)—X(2)
B(1)—O(1)
B(1)—O(2)
B(1)—O(2)
B(1)—O(3)
Si—Cmean
O(1)—C(7)
C(13)—O(2)
B—Fmean
N(1)—C(7)
Si(1)—O(1)
Si(2)—O(1)
Angle
—
—
—
2.918(2)
1.620(1)
1.608(1)
1.523(2)
—
2.990
1.642
1.634
1.553
—
2.816
2.117
2.083
1.553
—
—
1.518(2)
—
1.448(2)
—
1.447(2)
—
1.461
—
1.457
—
1.442(2)
1.866
1.302(2)
1.346(2)
1.381
1.318(2)
1.6397(9)
1.641(1)
ω/deg
—
1.864(2)
1.305(2)
1.345(2)
1.380(2)
1.312(2)
—
1.864(2)
1.301(1)
1.347(1)
1.386(2)
1.315(1)
—
1.875
1.282
1.282
1.368
1.333
—
1.881
1.282
1.282
1.369
1.333
—
—
—
—
—
O(1)—Si(1)—X(1)
O(1)—B(1)—O(2)
O(1)—B(1)—O(3) 109.2(1)
162.7(2)
109.8(1)
—
162.8(1)
109.32(9)
—
158.7
106.7
—
162.3
106.4
—
—
C—Si(1)—X(1)
X(2)—Si(2)—C
C—Si(1)—C
C—Si(2)—C
Si(1)—O(1)—Si(2) 130.79(6)
—
—
104.73(7)
107.37(7)
113.74(8)
111.46(8)
—
108.89(7)
107.77(6)
113.95(7)
111.08(7)
—
105.5
107.00
113.10
111.80
—
104.26
108.07
113.87
110.80
—
110.68(7)
110.76(8)

1
928
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
Korlyukov et al.
which was developed by Bader,19 as the main theoretical
approach. This method is based on the topological analyꢀ
sis of the calculated or experimental electron density disꢀ
tribution ρ(r) and allows one not only to demonstrate the
presence of interaction between atoms but also to reveal
Table 3. Topological parameters of molecules 5 and 6 in the
crystals and in the isolated state
Bond
Crystal
MPW1PW91/6ꢀ311G(d)
6
5
6
2
0—24
its nature and estimate its strength.
The experimenꢀ
ρ(r)/e•Å–3
0.78
tal electron density function was reproduced from the
results of highꢀprecision Xꢀray diffraction study of the
crystal of 6. The functions ρ(r) of isolated molecules 5
and 6 were calculated by the quantumꢀchemical
MPW1PW91/6ꢀ311G(d) method.
Qualitative analysis of the character of chemical bonds
in the crystal of 6 using sections of the experimental deꢀ
formation electron density (DED, see Fig. 2) showed that
Si(1)—X(1)
Si(2)—X(2)
Si—C
B(1)—O(2)
B(1)—O(1)
0.72
0.78
0.98
0.95
1.04
0.59
0.63
0.77
0.82
1.16
0.81
0.83
0.81
1.07
∇ 2
–5
ρ(r)/e•Å
20.97
21.77
5.12
Si(1)—Cl(1)
Si(2)—Cl(2)
Si—C
B(1)—O(2)
B(1)—O(1)
–1.39
–1.80
–5.80
10.38
16.84
3.95
4.60
4.61
10.82
22.14
its accumulation on the Si(1)...O(1) line is at most
10.85
13.98
E (r)/H•Å
–0.13
–3
0
.1 е Å . This is indicative of the fact that none of the
electron pairs of the O(1) atom is localized on the
Si(1)...O(1) line. The DED maxima corresponding to the
lone pairs of the O(1) atom are located at an angle of
approximately 35° with respect to the Si(1)...O(1) line.
Therefore, these lone pairs together with the B(1)—O(1)
and C(7)—O(1) bonds form an imaginary tetrahedron.
Topological analysis of the functions ρ(r) (see Table 3)
in the crystal of 6 and isolated molecules 5 and 6 revealed
the presence of the critical points (CP) (3, –1) in the
regions of all the expected bonds. The critical points CP
(3, –1) for the C—C, N—C, and O—C bonds are characꢀ
terized by negative values of the Laplacian of the electron
e
–3
Si(1)—Cl(1)
Si(2)—Cl(2)
Si—C
B(1)—O(1)
B(1)—O(2)
–0.50
–0.60
–0.91
–0.50
–0.47
–0.32
–0.34
–0.48
–0.53
–0.73
–0.13
–0.50
–0.51
–0.79
cations in directions corresponding to the O...Si bonding
vector in compounds 5 and 6, although these directions
are not favorable.1 They could become more favorable
due, apparently, to asymmetry of the O(1)—B(1) and
O(1)—C(7) bonds. The former bond is substantially elonꢀ
gated (~1.52 Å) compared to the standard value (1.47 Å)
3
2
e
density ∇ ρ(r) and the local electron energy density E (r),
which corresponds to shared (covalent) interactions
in terms of the AIM theory. The Si—F and B—O
bonds correspond to interactions of an intermediate type
for the tetracoordinate B atom, whereas the latter bond
length (see Table 2) is typical1
4,15
of compounds bearing a
2
e
boronꢀcontaining ring of this type. One cannot make an
unambiguous conclusion about the presence of an interꢀ
action between the Si(1) and O(1) atoms based only on
the structural data. Hence, we carried out quantumꢀ
chemical calculations of isolated molecules 5 and 6 using
the density functional theory (MPW1PW91/6ꢀ311G(d))
and performed highꢀprecision Xꢀray diffraction study of
the crystal of compound 6.
(∇ ρ(r) > 0, E (r) < 0 at CP (3, –1)), which is consistent
with the calculated data for organometallic compounds
1
9,20
containing such bonds.
e
The electron densities ρ(r) and E (r) at the CPs (3, –1)
for the Si(1)—X(1) bonds in molecules 5 and 6, which
serve (according to the AIM theory) as criteria of the
strength of interatomic interactions, are substantially lower
that those at the CPs (3, –1) for the Si(2)—X(2) bonds.
Therefore, the analysis of the topological characteristics
of the Si(1)—X(1) and Si(2)—X(2) bonds confirms the
assumption (which was based on the analysis of these
bond lengths) that the Si(1)—X(1) bond is weaker comꢀ
pared to the Si(2)—X(2) bond. Presumably, this weakenꢀ
ing is associated with the presence of the intramolecular
O(1)→Si(1) coordination bond in compounds 5 and 6.
An interesting characteristic feature of the Si—C and
Si—Cl bonds in dichloride 6 is that their CPs (3, –1) are
located in the vicinity of the interface between the regions
of electron density depletion and accumulation. In the
crystals, the CPs (3, –1) for the Si—C and Si—Cl bonds
Electronic structures of compounds 5 and 6. Quantumꢀ
chemical calculations demonstrated that the structures of
isolated molecules 5 and 6 are similar to those in the
crystals (see Table 2). The calculated geometry of the
coordination unit of the Si(1) atom agrees, on the whole,
well with the experimental data. The Si(1)...O(1) interꢀ
atomic distance in dichloride 6 is even somewhat shorter
than the experimental value. This fact is unexpected beꢀ
cause the Si...O(N) interatomic distances in isolated molꢀ
ecules of fiveꢀ and sixꢀmembered monochelates and
silatranes are substantially longer than the corresponding
distances in their crystals.1
6—18
2
The results of study of the electronic structures of
compounds 5 and 6 are of most interest. We used the
topological theory known as "Atoms in Molecules" (AIM),
fall in the region of accumulation of ρ(r) (∇ ρ(r) < 0),
whereas these critical points in the isolated molecules are
2
in the region of electron density depletion (∇ ρ(r) > 0). In

Salicylamideꢀbased B,Siꢀcontaining chelates
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
1929
all cases, the sign of the local energy density is negative.
Therefore, in the crystal the bonds under consideration
correspond to shared interactions, whereas the calculated
values correspond to interactions of an intermediate type.
Analysis of the Si—C and Si—Cl bond lengths demonꢀ
strated that the calculated values are slightly larger than
those determined from the experiment. Apparently, elonꢀ
gation of the calculated Si—C and Si—Cl bonds in molꢀ
ecule 6 leads to a shift of the corresponding CPs (3, –1)
toward the region of electron density depletion and a
change in the type of interactions.
The topological analysis revealed no CP (3, –1) on
the Si(1)...O(1) line, which is indicative of the absence of
the O(1)→Si(1) coordination bond in molecules 5 and 6.
The latter fact does not contradict an elongation of
the Si(1)—X(1) bond compared to the Si(2)—X(2) bond
observed in molecules 5 and 6. In dichloride 6, the calcuꢀ
lated dipole moment is very high (8.63 D), which is eviꢀ
dence that the positive and negative charges in this comꢀ
pound are localized on opposite sides of the molecule. An
analogous charge distribution is observed in tetrafluoꢀ
ride 5, in spite of the fact that its dipole moment is subꢀ
stantially smaller (3.6 D), which is attributable to the fact
that the Si—F bond has a lower ability to be polarized
compared to the Si—Cl bond. The Mulliken population
analysis of the charge distribution (we did not use the
more advanced NBO scheme because of restrictions imꢀ
posed by the available software) demonstrated that the
9 mmol) was added dropwise to disilamorpholine 3 (4.0 g,
3.5 mmol), which was placed in a flask equipped with a
dephlegmator, a thermometer, and a condenser. The reaction
mixture was heated until elimination of the ether ceased and
then cooled. Crystals were prepared by the addition of diethyl
ether (10 mL). The yield of compound 4 was 2.1 g (45%), m.p.
1
1
67—170 °C (toluene). Found (%): C, 45.58; H, 5.83, N, 4.14.
C H BF NO Si . Calculated (%): C, 45.48; H, 5.87; N, 4.08.
13
20
2
3
2
IR (CHCl ), ν/cm–1: 1620 (NCO), 1600 (Ar). 1H NMR
3
(CDCl ), δ: 0.17 and 0.26 (both s, 2 SiMe ); 3.35 and 3.50
3
2
(both s, 2 CH2); 6.85 (t), 7.09 (d), 7.52 (t), 7.55 (d) (4 H,
3
29
H arom., J
= 8.3 Hz). Si NMR (CDCl ), δ: 8.8 and 11.7
H,H
3
(
both s). Crystals of difluoride 4 suitable for Xꢀray diffraction
study were grown by recrystallization from toluene.
O—B)ꢀChelate 2ꢀ(difluoroboroxy)ꢀN,Nꢀbis(fluorodimethylꢀ
silylmethyl)benzamide (5). A. Boron trifluoride etherate (0.96 g,
(
6
6
.8 mmol) was added dropwise to disilamorpholine 3 (2.0 g,
.8 mmol), which was placed in a flask equipped with a
dephlegmator, a thermometer, and a condenser. The reaction
mixture was heated until elimination of the ether ceased and
then cooled, after which benzene (5 mL) was added and comꢀ
pound 4 was obtained in a yield of 1.2 g (3.5 mmol), m.p.
–
1
1
1
68—171 °C (benzene). IR (CHCl ), ν/cm : 1620 (NCO),
3
600 (Ar). The solvent was removed and the residue was crystalꢀ
lized by the addition of diethyl ether. Compound 5 was obtained
in a yield of 0.5 g (1.4 mmol), m.p. 69—72 °C (diethyl ether).
–1
1
IR (CHCl ), ν/cm : 1620, 1585 (NCO), 1600 (Ar). H NMR
3
3
(
CDCl ), δ: 0.46 and 0.51 (both d, 2 SiMe , J
3.34, 3.63 (both d, 2 CH , J
7.54 (t), 7.55 (d) (4 H, H arom., J
(CDCl3), δ: –1.54 and −2.07 (both d, 2 SiMe2, JC,F = 21.3 Hz);
5.89 and 46.54 (both d, 2 CH2, JC,F = 29.1 Hz); 110.52,
19.35, 121.64, 127.68, 136.81, 161.58 (C arom.); 166.21 (C=O).
= 8.4 Hz);
3
2
H,F
3
= 6.0 Hz); 6.97 (t), 7.18 (d),
2
H,F
3
13
= 8.3 Hz). C NMR
H,H
2
2
4
1
negative charge is accumulated in the region of the OBF O
2
fragment (the charges for the O(1), O(2), and F atoms
are, on average, –0.37, –0.32, and –0.26 е, respectively),
whereas the silicon atoms bear the highest positive charges
2
9
1
Si NMR (CDCl ), δ: 26.8 (d, JSi,F = 287.1 Hz); 27.6 (d,
3
1JSi,F = 283.4 Hz). Found (%): C, 43.11; H, 5.45; N, 3.82.
C H BF NO Si . Calculated (%): C, 42.74; H, 5.52; N, 3.83.
13
20
4
2
2
(
aver., 1.15 е).
Crystals of compound 5 suitable for Xꢀray diffraction analysis
were grown from diethyl ether.
The short distance between the Si(1) atom and the
OBF O fragment indicates that the intramolecular Couꢀ
B. Boron trifluoride etherate (1.21 g, 8.5 mmol) was added
dropwise to disilamorpholine 3 (1.5 g, 5.1 mmol). The reaction
mixture was gradually heated to 165 °C and then cooled, after
which benzene (5 mL) was added and the reaction mixture was
brought to reflux. The benzene was removed from the filtrate
and the residue was crystallized by adding diethyl ether. Comꢀ
2
lomb interaction between these atoms is responsible for a
substantial elongation of the Si(1)—X(1) bond compared
to the Si(2)—X(2) bond.
To summarize, analysis of the electronic structures of
molecules 5 and 6 and NMR spectroscopic study of these
molecules showed that the intramolecular O(1)→Si(1)
coordination interaction, which could be assumed based
on the structure of the coordination unit of the silicon
atom, is absent in these compounds.
pound 5 was obtained in a yield of 0.9 g (49%), m.p. 69—72 °C
–1
(
diethyl ether). IR (CHCl ), ν/cm : 1620, 1585 (NCO),
3
1
600 (Ar).
C. Boron trifluoride etherate (0.16 g, 1.16 mmol) was added
dropwise to difluoride 4 (0.6 g, 1.75 mmol). The reaction mixꢀ
ture was slowly heated to 155 °C and then cooled, after which
benzene (5 mL) was added and the reaction mixture was brought
to reflux and filtered. The solvent was removed from the filtrate
and the residue was crystallized by adding diethyl ether (2 mL).
Tetrafluoride 5 was obtained in a yield of 0.4 g (63%), m.p.
69—72 °C (diethyl ether).
Experimental
The IR spectra of solutions were recorded in KBr cells on a
1
13
twoꢀbeam Specord IRꢀ75 spectrometer. The H, C, and
2
9
Si NMR spectra of solutions in CDCl were measured on a
3
Varian XLꢀ400 spectrometer operating at 400.0, 100.6, and
(O—B)ꢀChelate N,Nꢀbis(chlorodimethylsilylmethyl)ꢀ2ꢀ(diꢀ
fluoroboroxy)benzamide (6). Freshly distilled thionyl chloride
(0.25 g, 2.07 mmol) was added dropwise with stirring to a mixꢀ
ture of disilamorpholine 3 (0.6 g, 1.75 mmol) and anhydrous
benzene (7 mL), the starting compound being dissolved. After
one day, the crystals that precipitated were filtered off and comꢀ
7
9.5 MHz, respectively, with Me Si as the internal standard.
4
The synthesis of the starting 4ꢀ(2ꢀhydroxybenzoyl)ꢀ2,2,6,6ꢀ
tetramethylꢀ2,6ꢀdisilamorpholine (3) has been described earlier.9
(
O—B)ꢀChelate 4ꢀ[2ꢀ(difluoroboroxy)benzoyl]ꢀ2,2,6,6ꢀdiꢀ
methylꢀ2,6ꢀdisilamorpholine (4). Boron trifluoride etherate (1.3 g,

1
930
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
Korlyukov et al.
pound 6 was obtained in a yield of 0.5 g (72%), m.p. 84—88 °C
with anisotropic displacement parameters for nonhydrogen atꢀ
oms. The hydrogen atoms were revealed from difference Fourier
syntheses and refined isotropically. All calculations were carꢀ
ried out using the SHELXTL PLUS program package (verꢀ
1
(
benzene). H NMR (CDCl ), δ: 0.38 and 0.46 (both s, 2 SiMe );
3 2
3
7
0
1
1
.38 and 3.59 (both s, 2 CH ); 6.98 (t), 7.18 and 7.53 (both d),
2
3
13
.57 (t) (4 H, H arom., J
= 8.1 Hz). C NMR (CDCl ), δ:
3
H,H
2
5
.25 and 0.57 (both s, 2 SiMe ); 47.67 and 49.98 (both s, 2 CH );
sion 5.10).
2
2
12.25, 118.99, 119.36, 128.01, 137.00, 162.87 (C arom.);
Processing of the data from highꢀprecision Xꢀray diffraction
experiment and quantumꢀchemical calculations. The experimenꢀ
tal electron density distribution in the crystal of compound 6
was determined by the multipole refinement of the Xꢀray difꢀ
67.99 (C=O). 29Si NMR (CDCl ), δ: 19.1 and 24.6 (both s).
3
Found (%): C, 38.67; H, 4.92; N, 3.16. C H BCl F NO Si .
13
20
2
2
2
2
Calculated (%): C, 39.21; H, 5.06; N, 3.52. Crystals of comꢀ
pound 6 suitable for Xꢀray diffraction study were withdrawn
directly from the reaction mixture.
Hydrolysis of 2ꢀ(difluoroboroxy)ꢀN,Nꢀbis(fluorodimethylꢀ
silylmethyl)benzamide (5). A sample of tetrafluoride 5 (0.3 g,
2
6
fraction data using the ХD program package. The refinement
was carried out against F using 6461 reflections (I > 4σ(I ),
θmax = 45°). For all nonhydrogen atoms, the coordinates, therꢀ
mal parameters, and multipole parameters up to the octupole
level (l = 3) were refined, except for the O, Si and Cl atoms for
which the multipole populations were refined up to hexaꢀ
decapoles (l = 4). For the C(1) and C(2) atoms of the Me
groups, the local C3v symmetry was assigned. Before the refineꢀ
ment, the C—H distances were normalized to 1.07 Å, which
0
.82 mmol) was stored in the presence of atmospheric moisture
for half year, during which the melting point increased to
59—163 °C. After recrystallization of the product from benꢀ
1
zene, disilamorpholine 3 was isolated in a yield of 0.2 g (71%),
m.p. 165—168 °C (benzene); a mixed sample was characterized
by m.p. 165—168 °C.
Xꢀray diffraction study of compounds 4, 5, and 6. The crystalꢀ
lographic parameters and principal details of Xꢀray diffraction
study for compounds 4, 5, and 6 are given in Table 4. Xꢀray
diffraction data sets were collected on Bruker Smart CCD 1000
1
4
corresponds to neutron diffraction data. For the H atoms, only
the dipole populations (l = 1) were refined, whereas the coordiꢀ
nates and thermal parameters were kept fixed. The maximum
number of parameters involved in the multipole refinement
was 528. The results of the multipole refinement were as follows:
R = 0.0337, wR = 0.0488, GOF = 1.073 based on 6461 reflecꢀ
tions with I > 4σ(I ). All calculations with full geometry optimiꢀ
zation were performed using the Gaussian 98W program suite
(
4 and 5) and Syntex P21 (6) diffractometers (MoꢀKα radiaꢀ
tion). The structures of 4, 5, and 6 were solved by direct methods
and refined by the fullꢀmatrix leastꢀsquares method against F 2
Table 4. Main details of Xꢀray diffraction study and crystallographic parameters for comꢀ
pounds 4, 5, and 6
Parameter
4
5
6
Molecular formula
C H BF NO Si
C H BF NO Si C H BCl F NO Si
13 20 4 2 2 13 20 2 2 2 2
1
3
20
2
3
2
Molecular weight
T/K
343.29
110(2)
365.29
110(2)
398.19
148(2)
a/Å
b/Å
c/Å
α/deg
β/deg
γ/deg
V/Å3
dcalc/g cm–3
Space group
Z
8.3912(3)
10.3590(4)
19.0837(7)
90
96.402(1)
90
9.3504(6)
9.5759(6)
11.2693(7)
112.238(1)
91.401(1)
109.811(1)
865.09(9)
7.435(3)
9.292(3)
14.140(5)
72.24(2)
83.69(3)
81.23(3)
917.4(6)
1648.5(1)
1.383
1.402
1.442
–
–
P2 /n
P1
P1
1
4
63
720
ω
2
2
90
412
θ/2θ
2
θmax/deg
60.0
380
ω
F(000)
Scanning technique
Number of measured
reflections
Number of independent
reflections (Rint
18451
7326
9185
8554 (0.032)
7370
)
5092 (0.059)
3963
4889 (0.070)
3935
Number of observed
reflections with I > 2σ(I )
Number of parameters
in refinement
279
288
288
Absorption
coefficient/cm–1
2.45
2.49
5.08
R (I > 2σ(I ))
wR2
0.0434
0.1264
0.0459
0.1294
0.0446
0.1320
1

Salicylamideꢀbased B,Siꢀcontaining chelates
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
1931
(
release A7)27 employing the MPW1PW91 hybrid functional
13. G. Chiari and G. Ferraris, Acta Crystallogr., 1982, B38, 2331.
14. F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G.
Orpen, and R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, S1.
15. Cambridge Structural Database, Release 2003.
and the 6ꢀ311G(d) basis set. The topological analysis of the
electron density distribution, which was extracted from the calꢀ
culated data, was carried out using the EXTREME program.
2
8
1
6. V. F. Sidorkin, E. F. Belogolova, and V. A. Pestunovich,
J. Mol. Struct. (Theochem.), 2001, 538, 59.
This study was financially supported by the Russian
Foundation for Basic Research (Project Nos 01ꢀ03ꢀ32999,
17. A. A. Korlyukov, K. A. Lyssenko, M. Yu. Antipin, V. N.
9
7ꢀ03ꢀ33783, 03ꢀ03ꢀ32214, and 02ꢀ07ꢀ90169) and the
Kirin, E. A. Chernyshev, and S. P. Knyazev, Inorg. Chem.,
2
002, 41, 5043.
INTAS (Grant 03ꢀ51ꢀ4164).
1
1
8. A. A. Korlyukov, K. A. Lyssenko, and M. Yu. Antipin, Izv.
Akad. Nauk, Ser. Khim., 2002, 1314 [Russ. Chem. Bull., Int.
Ed., 2002, 51, 1423].
9. R. F. W. Bader, Atoms in Molecules. A Quantum Theory,
Clarendron Press, Oxford, 1990.
20. K. A. Lyssenko and M. Yu. Antipin, Izv. Akad. Nauk, Ser.
Khim., 2001, 400 [Russ. Chem. Bull., Int. Ed., 2001, 50, 418].
21. T. S. Koritsanszky and P. Coppens, Chem. Rev., 2001,
101, 1583.
22. E. Espinosa, E. Mollins, and C. Lecomte, Chem. Phys. Lett.,
1998, 285, 170.
23. V. Jonas, G. Frenking, and M. T. Reetz, J. Am. Chem. Soc.,
1994, 116, 8741.
24. J. M. Molina and J. A. Dobado, Theor. Chem. Acc., 2001,
105, 328.
25. G. M. Sheldrick, SHELXTLꢀ97, V5.10, 1997, Bruker AXS
Inc., Madison, WIꢀ53719, USA.
26. T. Koritsansky, S. T. Howard, T. Richter, P. R. Mallinson,
Z. Su, and N. K. Hansen, XD, a Computer Program Package
for Multipole Refinement and Analysis of Charge Densities from
Xꢀray Diffraction Data, 1995.
27. M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, V. G. Zakrzewski, J. A.
Montgomery, Jr., R. E. Stratmann, J. C. Burant,
S. Dapprich, J. M. Millam, A. D. Daniels, K. N. Kudin,
M. C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi,
R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford,
J. Ochterski, G. A. Petersson, P. Y. Ayala, Q. Cui,
K. Morokuma, D. K. Malick, A. D. Rabuck,
K. Raghavachari, J. B. Foresman, J. Cioslowski, J. V. Ortiz,
A. G. Baboul, B. B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R. Gomperts, R. L. Martin, D. J.
Fox, T. Keith, M. A. AlꢀLaham, C. Y. Peng, A. Nanayakkara,
M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, J. L. Andres, C. Gonzalez, M. HeadꢀGordon,
E. S. Replogle, and J. A. Pople, Gaussian 98, Revision A.7,
Gaussian, Inc., Pittsburgh (PA), 1998.
References
. Yu. I. Baukov, A. G. Shipov, E. P. Kramarova, E. A.
Mamaeva, O. A. Zamyshlyaeva, N. A. Anisimova, and
Vad. V. Negrebetsky, Zh. Org. Khim., 1996, 32, 1259 [Russ.
J. Org. Chem., 1996, 32 (Engl. Transl.)].
. E. A. Mamaeva, O. V. Agafonova, Vad. V. Negrebetsky,
A. G. Shipov, Yu. I. Baukov, and A. S. Losev,
Khim.ꢀfarm. Zh., 1994, No. 6, 26 [Pharm. Chem. J., 1994,
No. 6 (Engl. Transl.)].
. A. V. Kurochka, O. A. Afanasova, A. S. Losev, E. A.
Mamaeva, S. Yu. Bylikin, Vad. V. Negrebetsky, E. P.
Kramarova, A. G. Shipov, and Yu. I. Baukov, MetalꢀBased
Drugs, 1998, 5, 25.
. E. P. Kramarova, Vad. V. Negrebetsky, A. G. Shipov, and
Yu. I. Baukov, Zh. Obshch. Khim., 1994, 64, 1222 [Russ. J. Gen.
Chem., 1994, 64 (Engl. Transl.)].
. O. A. Zamyshlyaeva, A. G. Shipov, E. P. Kramarova, Vad. V.
Negrebetsky, Yu. E. Ovchinnikov, S. A. Pogozhikh, and
Yu. I. Baukov, Khim. Geterotsikl. Soedin., 1999, 1077 [Chem.
Heterocycl. Compd., 1999 (Engl. Transl.)].
1
2
3
4
5
6
7
. C. Chuit, R. J. P. Corriu, C. Reye, and J. C. Yuong, Chem.
Rev., 1993, 93, 1371.
. A. G. Shipov, E. P. Kramarova, E. A. Mamaeva, O. A.
Zamyshlyaeva, Vad. V. Negrebetsky, Yu. E. Ovchinnikov,
S. A. Pogozhikh, A. R. Bassindale, P. G. Taylor, and Yu. I.
Baukov, J. Organometal. Chem., 2001, 620, 139.
. A. G. Shipov, E. P. Kramarova, S. Yu. Bylikin, E. A. Mamaeva,
G. S. Zaitseva, V. N. Sergeev, and Yu. I. Baukov, Zh. Org.
Khim., 1993, 63, 1195 [Russ. J. Org. Chem., 1993, 63 (Engl.
Transl.)].
. O. A. Zamyshlyaeva, A. G. Shipov, E. P. Kramarova, Vad. V.
Negrebetsky, A. N. Shumskii, S. N. Tandura, S. Yu. Bylikin,
Yu. E. Ovchinnikov, S. A. Pogozhikh, and Yu. I. Baukov,
Khim. Geterotsikl. Soedin., 2002, 127 [Chem. Heterocycl.
Compd., 2002 (Engl. Transl.)].
8
9
28. J. Cheeseman, T. A. Keith, and R. W. F. Bader, AIMPAC
Program Package, McMaster University, Hamilton,
Ontario, 1992.
1
0. J. Morris, Y. Fang, D. J. Wishka, and F. Han, Tetrahedron
Lett., 1993, 34, 3817.
1
1
1. A. Bondi, J. Phys. Chem., 1964, 68, 441.
2. Yu. E. Ovchinnikov, A. A. Macharashvili, Yu. T. Struchkov,
A. G. Shipov, and Yu. I. Baukov, Zh. Strukt. Khim., 1994,
Received May 17, 2004;
3
5, 100 [Russ. J. Struct. Chem., 1994, 35 (Engl. Transl.)].
in revised form August 30, 2004