Formation of a macrocycle from dichlorodimethylsilane and a pyridoxalimine Schiff base ligand

Abstract

The reaction of dichlorodimethylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2-ethanolamine yielded the macrocyclic silicon compound (8 E ,22 E )-4,4,12,18,18,26-hexamethyl-3,5,17,19-tetraoxa-8,13,22,27-tetraaza-4,18-disilatricyclo[22.4.0.0 10,15 ]octacosa-1(24),8,10,12,14,22,25,27-octaene-11,25-diol, C 24 H 36 N 4 O 6 Si 2 . The asymmetric unit contains the half macrocycle with an intramolecular O—H...N hydrogen bond between the imine nitrogen atom and a neighbouring oxygen atom. The crystal structure is dominated by C—H...O and C—H...π interactions, which form a high ordered molecular network.

Full text

research communications
Acta Cryst. (2021). E77 https://doi.org/10.1107/S2056989021010185 1of4
Received 24 September 2021
Accepted 1 October 2021
Edited by O. Blacque, University of Zu
¨rich,
Switzerland
Keywords: crystal structure; organosiloxane;
pyridoxal; Schiff base; macrocycle.
CCDC reference:2113407
Supporting information:this article has
supporting information at journals.iucr.org/e
Formation of a macrocycle from dichlorodimethyl-
silane and a pyridoxalimine Schiff base ligand
Uwe Bo
¨hme,
a
* Anke Schwarzer
b
and Betty Gu
¨nther
a
a
Institut fu
¨r Anorganische Chemie, Technische Universita
¨t Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg,
Germany, and
b
Institut fu
¨r Organische Chemie, Technische Universita
¨t Bergakademie Freiberg, Leipziger Str. 29, 09599
Freiberg, Germany. *Correspondence e-mail: uwe.boehme@chemie.tu-freiberg.de
The reaction of dichlorodimethylsilane with a polydentate Schiff base ligand
derived from pyridoxal and 2-ethanolamine yielded the macrocyclic silicon
compound (8E,22E)-4,4,12,18,18,26-hexamethyl-3,5,17,19-tetraoxa-8,13,22,27-
tetraaza-4,18-disilatricyclo[22.4.0.0
10,15
]octacosa-1(24),8,10,12,14,22,25,27-octa-
ene-11,25-diol, C
24
H
36
N
4
O
6
Si
2
. The asymmetric unit contains the half macro-
cycle with an intramolecular O—HN hydrogen bond between the imine
nitrogen atom and a neighbouring oxygen atom. The crystal structure is
dominated by C—HOandC—Hinteractions, which form a high ordered
molecular network.
1. Chemical context
The heterocyclic aldehyde pyridoxal is one of the active forms
of vitamin B
6
. This vitamin is an essential cofactor to a large
number of enzymes that catalyze many reactions of amino
acids (Sykes et al., 1991). The coordination chemistry of Schiff
bases generated from amino acids and pyridoxal with trans-
ition metal ions has been investigated intensive (Christensen,
1957; Long et al., 1980; Dawes et al., 1982; Walz et al., 1983; Rao
et al., 1985; Astheimer et al., 1985; Sykes et al., 1991; Costa
Pessoa et al., 1999). We are working on silicon complexes with
tridentate O,N,O-ligands (Bo
¨hme & Gu
¨nther, 2007a;Bo
¨hme
et al., 2006; Paul et al., 2014; Warncke et al., 2012; Schwarzer et
al., 2018). Therefore, we prepared a Schiff base from pyridoxal
and 2-aminoethanol as a potential O,N,O-ligand. The crystal
structure of this molecule, 4-[(2-hydroxyethyl)iminomethyl]-5-
hydroxymethyl-2-methylpyridine-3-ol (I), was published
earlier (Bo
¨hme & Gu
¨nther, 2007b). Compound (I) was used
recently as ligand molecule to coordinate copper and silver
ions (Annaraj & Neelakantan, 2014, 2015). Herein we report
the results of reaction between (I) and dichlorodimethylsilane.
There are several potential coordination sites at the ligand
molecule (I): the pyridine and the imino nitrogen atoms, two
aliphatic and one phenolic hydroxyl groups. The presence of
these functional groups makes it difficult to predict the
structure of the reaction product with dichlorodimethylsilane.
It was our initial goal to prepare a pentacoordinate silicon
complex like (II). Surprisingly the macrocyclic silicon
compound (III) was obtained from the reaction of (I) with
Me
2
SiCl
2
. The reaction was performed in tetrahydrofuran in
presence of triethylamine as supporting base to remove the
hydrogen chloride, which is formed during the reaction.
Recrystallization of the raw product from 1,2-dimethoxy-
ethane and diethyl ether gave yellow crystals suitable for
structure analysis.
ISSN 2056-9890

2. Structural commentary
Compound (III) crystallizes in the monoclinic space group I2/c
with the half macrocycle in the asymmetric unit. Fig. 1 shows
the asymmetric unit and the atomic labelling scheme. The
macrocycle is generated by a crystallographic C2 axis through
the centre of the macrocycle (Fig. 2). The silicon atom is
bound to the two methyl groups and to the aliphatic oxygen
atoms O2 and O3, thus forming a macrocycle (Fig. 2). A quite
similar macrocycle has been obtained from the reaction of a
related pyridoxal-derived Schiff base and dichlorodiphenyl-
silane (Bo
¨hme et al., 2008). The short Si—O bonds (see
Table 1) are in the range for comparable Si—O bonds (Wagler
et al., 2005; Bo
¨hme et al., 2006, 2008; Bo
¨hme & Gu
¨nther, 2007a;
Bo
¨hme & Foehn, 2007). The silicon atom is distorted tetra-
hedral with bond angles between 103.40 (5) and 113.16 (7)
(Table 1). The rather large bond angles at the oxygen atoms
(see Table 1) have been explained by the ionic character of the
Si—O bonds (Gillespie & Johnson, 1997). There is a strong
intramolecular O—HN interaction (entry 1, Table 2)
between the imine nitrogen atom N2 and the O1—H1 group in
the neighbouring position at the pyridoxal ring. The formation
of hydrogen bridges between the imine nitrogen atom and an
ortho-hydroxyl group is a feature that is often observed in
Schiff bases with o-hydroxy groups (Ho
¨kelek et al., 2004;
Filarowski et al., 1999). This strong intramolecular O—HN
interaction leads to a six-membered pseudo ring consisting of
H1—O1—C2—C3—C7—N2. This pseudo ring is planar with
an r.m.s. deviation of 0.009 A
˚from the ring plane. According
to the graph-set notation proposed by Etter et al. (1990), these
2of4 Bo
¨hme et al. C
24
H
36
N
4
O
6
Si
2
Acta Cryst. (2021). E77
research communications
Figure 2
The molecular structure of (III), drawn with 50% probability displace-
ment ellipsoids.
Table 1
Selected geometric parameters (A
˚,).
Si1—O2 1.6435 (9) Si1—C12 1.8443 (14)
Si1—O3
i
1.6487 (9) Si1—C11 1.8589 (15)
O2—Si1—O3
i
103.40 (5) O3
i
—Si1—C11 109.52 (6)
O2—Si1—C12 106.94 (6) C12—Si1—C11 113.16 (7)
O3
i
—Si1—C12 112.06 (6) C8—O2—Si1 123.61 (8)
O2—Si1—C11 111.33 (7) C10—O3—Si1
i
123.50 (8)
Symmetry code: (i) xþ2;y;zþ1
2.
Figure 1
The asymmetric unit of (III), drawn with 50% probability displacement
ellipsoids. The dashed line shows the intramolecular O1—H1N2
hydrogen bond.

hydrogen bonds form motifs with an S1
1(6) graph-set
descriptor. The hydrogen bonds C7—H7O3 link different
parts within one macrocycle via intra-annular hydrogen bonds
(Fig. 2).
3. Supramolecular features
A bifurcated intermolecular C—HO interaction is
observed at O2 (Table 2). The interaction of C6—H6AO2
and C5—H5O1 results in a chain along the crystallographic
b-axis. The C—HO interaction of C9—H9Bwith O2
connects adjacent chains (Fig. 3).
Apart from the relevant C—HO interaction, two C—
Hcontacts with the pyridine moiety (Cg1) are observed.
First, a bifurcation at H9B(d=3.31A
˚) shows up within the
C—HO chains along the caxis. Furthermore, C11—
H11ACg1(d=2.85A
˚) supports the C—HO interactions
of H5 and H6A.
In summary, the crystal structure is dominated by C—
HO and C—Hinteractions, forming a highly ordered
molecular network.
The potential bonding sites in combination with the cavity
of the macrocycle makes (III) a suitable candidate for
supramolecular recognition processes. The available pyridine
N, azomethine N, and OH groups could be useful for the
generation of nanostructures via complexation with transition
metals (Leininger et al., 2000).
4. Database survey
A CSD search with ConQuest (Bruno et al., 2002) for
macrocycles containing Schiff bases from pyridoxal and
2-aminoalcohols showed that only one comparable silicon
compound exists (Bo
¨hme et al., 2008, refcode MOKVEO).
The main differences between these two structures of silicon-
containing macrocycles are as follows. First, (III) was found to
crystallize without solvent while MOKVEO encloses chloro-
fom molecules. Probably as a result, the symmetry is lower in
MOKVEO (triclinic, P1) than in (III) showing the monoclinic
I2/csymmetry. On the basis of the structure of (III) presented
here and the former investigation (Bo
¨hme et al., 2008), it can
be assumed that pyridoxalimine-derived Schiff bases prefer
the formation of macrocycles with diorganosilane units.
However, it seems to be possible that compound (I) can also
act as a tridentate O,N,O-ligand, as was shown recently with a
hexacoordinate titanium complex (Bo
¨hme & Gu
¨nther, 2020).
5. Synthesis and crystallization
The preparation of (III) was performed in Schlenk tubes
under argon with dry and air-free solvents.
Compound (III) was prepared by reaction of 4-[(2-hy-
droxyethyl)iminomethyl]-5-hydroxymethyl-2-methylpyridine-
3-ol (I) (1.7 g, 8 mmol) with dichlorodimethylsilane (1.03 g,
8 mmol) in the presence of triethylamine (2.02 g, 20 mmol).
The reaction was performed in dry tetrahydrofuran at room
temperature. A white precipitate of triethylamine hydro-
chloride formed upon stirring of the mixture for five days.
After this period, the triethylamine hydrochloride was filtered
off and washed with tetrahydrofuran. The solvent was
removed in vacuo from the resulting clear yellow solution. The
remaining solid was extracted with 1,2-dimethoxyethane.
Addition of diethyl ether and cooling to 278 K yielded yellow
crystals of (III) (1.66 g, 78%, m.p. 390 K).
NMR (CDCl
3
, 300 K, TMS, in p.p.m.):
29
Si: 0.1.
1
H: =
0.14 (
s
,Me
2
Si, 6H), 2.50 (s,CH
3
pyridoxal, 3H), 3.71, 3.90 (t,
N—CH
2
—CH
2
—O, 4H), 4.78 (s,CH
2
—O pyridoxal, 2H), 7.89
(s, CH pyridoxal, 1H), 8.84 (s,HC N, 1H), 14.05 (s,OH
pyridoxal, 1H).
13
C: 3.0 (Me
2
Si), 22.0 (CH
3
pyridoxal), 63.3,
64.6 (N—CH
2
—CH
2
—O), 66.4 (CH
2
—O pyridoxal), 122.6,
133.4, 140.8, 153.8, 157.8 (five C pyridoxal), 167.5 (HC N).
6. Refinement
Crystal data, data collection and structure refinement details
are summarized in Table 3. The hydrogen atom at O1 was
refined freely. The methyl groups were refined as idealized
rigid groups allowed to rotate but not tip (AFIX 137; C—H =
0.98 A
˚, H—C—H = 109.5). Other hydrogens were included
using a riding model starting from calculated positions (C—
H
aromatic
= 0.95, C—H
methylene
=0.99A
˚). The U
iso
(H) values
were fixed at 1.5 (for the methyl H) or 1.2 times the equivalent
U
eq
value of the parent carbon atoms.
research communications
Acta Cryst. (2021). E77 Bo
¨hme et al. C
24
H
36
N
4
O
6
Si
2
3of4
Table 2
Hydrogen-bond geometry (A
˚,).
Cg1 is the centroid of the N1/C1–C5 ring.
D—HAD—H HADAD—HA
O1—H1N2 0.90 (2) 1.76 (2) 2.5923 (15) 153.2 (18)
C5—H5O1
ii
0.95 2.69 3.5451 (16) 151
C6—H6AO2
iii
0.98 2.59 3.3464 (17) 134
C7—H7O3
i
0.95 2.57 3.4882 (15) 162
C9—H9BO2
iv
0.99 2.60 3.5087 (16) 153
C9—H9BCg1
iv
0.99 3.31 4.039 (2) 131
C11—H11ACg1
ii
0.98 2.85 3.7880 (2) 160
Symmetry codes: (i) xþ2;y;zþ1
2; (ii) x;yþ1;z1
2; (iii) x;yþ1;zþ1
2; (iv)
xþ3
2;yþ1
2;zþ1
2.
Figure 3
Packing excerpt of (III) showing C—HO hydrogen bonds (dashed
lines).

Funding information
Funding for this research was provided by: Open Access
Funding by the Publication Fund of the TU Bergakademie
Freiberg .
References
Annaraj, B. & Neelakantan, M. A. (2014). Anal. Methods 6, 9610–
9615.
Annaraj, B. & Neelakantan, M. A. (2015). Eur. J. Med. Chem. 102,1–
8.
Astheimer, H., Nepveu, F., Walz, L. & Haase, W. (1985). J. Chem. Soc.
Dalton Trans. pp. 315–320.
Bo
¨hme, U. & Foehn, I. C. (2007). Acta Cryst. C63, o613–o616.
Bo
¨hme, U. & Gu
¨nther, B. (2007a). Inorg. Chem. Commun. 10, 482–
484.
Bo
¨hme, U. & Gu
¨nther, B. (2007b). Acta Cryst. C63, o641–o642.
Bo
¨hme, U. & Gu
¨nther, B. (2020). CSD Communication (CCDC No.
2048270). CCDC, Cambridge, England. https://dx.doi.org/10.5517/
ccdc.csd.cc26rd7m
Bo
¨hme, U., Gu
¨nther, B. & Schwarzer, A. (2008). Acta Cryst. C64,
o630–o632.
Bo
¨hme, U., Wiesner, S. & Gu
¨nther, B. (2006). Inorg. Chem. Commun.
9, 806–809.
Bruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M., Macrae, C. F.,
McCabe, P., Pearson, J. & Taylor, R. (2002). Acta Cryst. B58, 389–
397.
Christensen, H. N. (1957). J. Am. Chem. Soc. 79, 4073–4078.
Costa Pessoa, J., Cavaco, I., Correia, I., Duarte, M. T., Gillard, R. D.,
Henriques, R. T., Higes, F. J., Madeira, C. & Tomaz, I. (1999). Inorg.
Chim. Acta,293, 1–11.
Dawes, H. M., Waters, J. M. & Waters, T. N. (1982). Inorg. Chim. Acta,
66, 29–36.
Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46,
256–262.
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.
Filarowski, A., Głowiaka, T. & Koll, A. (1999). J. Mol. Struct. 484, 75–
89.
Gillespie, R. J. & Johnson, S. A. (1997). Inorg. Chem. 36, 3031–3039.
Ho
¨kelek, T., Bilge, S., Demiriz, S¸., O
¨zgu
¨c¸, B. & Kılıc¸, Z. (2004). Acta
Cryst. C60, o803–o805.
Leininger, S., Olenyuk, B. & Stang, P. J. (2000). Chem. Rev. 100, 853–
908.
Long, G. J., Wrobleski, J. T., Thundathil, R. V., Sparlin, D. M. &
Schlemper, E. O. (1980). J. Am. Chem. Soc. 102, 6040–6046.
Paul, L. E. H., Foehn, I. C., Schwarzer, A., Brendler, E. & Bo
¨hme, U.
(2014). Inorg. Chim. Acta,423, 268–280.
Rao, S. P. S., Manohar, H. & Bau, R. (1985). J. Chem. Soc. Dalton
Trans. pp. 2051–2057.
Schwarzer, S., Bo
¨hme, U., Fels, S., Gu
¨nther, B. & Brendler, E. (2018).
Inorg. Chim. Acta,483, 136–147.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8.
Stoe (2009). X-RED and X-AREA. Stoe & Cie, Darmstadt, Germany.
Sykes, A. G., Larsen, R. D., Fischer, J. R. & Abbott, E. H. (1991).
Inorg. Chem. 30, 2911–2916.
Wagler, J., Bo
¨hme, U., Brendler, E., Thomas, B., Goutal, S., Mayr, H.,
Kempf, B., Remennikov, G. Y. & Roewer, G. (2005). Inorg. Chim.
Acta,358, 4270–4286.
Walz, L., Paulus, H., Haase, W., Langhof, H. & Nepveu, F. (1983). J.
Chem. Soc. Dalton Trans. pp. 657–664.
Warncke, G., Bo
¨hme, U., Gu
¨nther, B. & Kronstein, M. (2012).
Polyhedron,47, 46–52.
4of4 Bo
¨hme et al. C
24
H
36
N
4
O
6
Si
2
Acta Cryst. (2021). E77
research communications
Table 3
Experimental details.
Crystal data
Chemical formula C
24
H
36
N
4
O
6
Si
2
M
r
532.75
Crystal system, space group Monoclinic, I2/c
Temperature (K) 153
a,b,c(A
˚) 12.9641 (8), 16.8966 (7),
13.1085 (8)
() 101.198 (5)
V(A
˚
3
) 2816.7 (3)
Z4
Radiation type Mo K
(mm
1
) 0.17
Crystal size (mm) 0.40 0.33 0.15
Data collection
Diffractometer Stoe IPDS 2T
Absorption correction Integration (X-RED; Stoe, 2009)
T
min
,T
max
0.907, 0.993
No. of measured, independent and
observed [I>2(I)] reflections
19293, 3242, 2833
R
int
0.039
(sin /)
max
(A
˚
1
) 0.650
Refinement
R[F
2
>2(F
2
)], wR(F
2
), S0.032, 0.082, 1.08
No. of reflections 3242
No. of parameters 169
H-atom treatment H atoms treated by a mixture of
independent and constrained
refinement

max
,
min
(e A
˚
3
) 0.32, 0.23
Computer programs: X-AREA and X-RED (Stoe, 2009), SHELXS (Sheldrick, 2008),
SHELXL2017/1 (Sheldrick, 2015) and ORTEP-3 for Windows (Farrugia, 2012).

supporting information
sup-1
Acta Cryst. (2021). E77
supporting information
Acta Cryst. (2021). E77 [https://doi.org/10.1107/S2056989021010185]
Formation of a macrocycle from dichlorodimethylsilane and a pyridoxalimine
Schiff base ligand
Uwe Böhme, Anke Schwarzer and Betty Günther
Computing details
Data collection: X-AREA (Stoe, 2009); cell refinement: X-AREA (Stoe, 2009); data reduction: X-RED (Stoe, 2009);
program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2017/1
(Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for
publication: SHELXL2017/1 (Sheldrick, 2015).
(8E,22E)-4,4,12,18,18,26-Hexamethyl-3,5,17,19-tetraoxa-8,13,22,27-tetraaza-4,18-
disilatricyclo[22.4.0.010,15]octacosa-1(24),8,10,12,14,22,25,27-octaene-11,25-diol
Crystal data
C24H36N4O6Si2
Mr = 532.75
Monoclinic, I2/c
a = 12.9641 (8) Å
b = 16.8966 (7) Å
c = 13.1085 (8) Å
β = 101.198 (5)°
V = 2816.7 (3) Å3
Z = 4
F(000) = 1136
Dx = 1.256 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 19293 reflections
θ = 3.2–28.8°
µ = 0.17 mm−1
T = 153 K
Prism, yellow
0.40 × 0.33 × 0.15 mm
Data collection
Stoe IPDS 2T
diffractometer
Radiation source: sealed X-ray tube, 12 x 0.4
mm long-fine focus
Plane graphite monochromator
Detector resolution: 6.67 pixels mm-1
rotation method scans
Absorption correction: integration
(X-RED; Stoe, 2009)
Tmin = 0.907, Tmax = 0.993
19293 measured reflections
3242 independent reflections
2833 reflections with I > 2σ(I)
Rint = 0.039
θmax = 27.5°, θmin = 2.0°
h = −16→16
k = −21→21
l = −16→16
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.032
wR(F2) = 0.082
S = 1.08
3242 reflections
169 parameters
0 restraints
Hydrogen site location: mixed
H atoms treated by a mixture of independent
and constrained refinement
w = 1/[σ2(Fo2) + (0.0343P)2 + 2.1897P]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max = 0.001
Δρmax = 0.32 e Å−3
Δρmin = −0.23 e Å−3

supporting information
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Acta Cryst. (2021). E77
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
xyz U
iso*/Ueq
Si1 0.86455 (3) 0.32645 (2) −0.02263 (2) 0.02075 (10)
O1 0.71097 (8) 0.39251 (6) 0.42399 (7) 0.0296 (2)
H1 0.7514 (16) 0.3499 (12) 0.4190 (14) 0.044*
O2 0.80401 (7) 0.38781 (5) 0.04330 (7) 0.02281 (19)
O3 1.06149 (7) 0.27321 (5) 0.43122 (7) 0.02520 (19)
N1 0.67254 (9) 0.55915 (7) 0.24920 (9) 0.0294 (2)
N2 0.83696 (8) 0.29351 (6) 0.35941 (8) 0.0230 (2)
C1 0.66458 (10) 0.51009 (8) 0.32707 (10) 0.0259 (3)
C2 0.72289 (10) 0.43890 (7) 0.34287 (9) 0.0233 (2)
C3 0.78833 (9) 0.41735 (7) 0.27376 (9) 0.0209 (2)
C4 0.79399 (10) 0.46943 (7) 0.19053 (9) 0.0229 (2)
C5 0.73609 (11) 0.53867 (8) 0.18313 (10) 0.0282 (3)
H5 0.741329 0.574080 0.128082 0.034*
C6 0.58959 (11) 0.53139 (9) 0.39701 (11) 0.0338 (3)
H6A 0.629045 0.540267 0.467780 0.051*
H6B 0.539444 0.488047 0.397491 0.051*
H6C 0.551402 0.579715 0.371352 0.051*
C7 0.84345 (9) 0.34072 (7) 0.28447 (9) 0.0206 (2)
H7 0.884566 0.326031 0.234897 0.025*
C8 0.85625 (10) 0.45009 (7) 0.10775 (10) 0.0252 (3)
H8A 0.861902 0.497621 0.065010 0.030*
H8B 0.928130 0.433117 0.140566 0.030*
C9 0.89177 (10) 0.21754 (7) 0.36341 (10) 0.0236 (2)
H9A 0.914711 0.208345 0.296627 0.028*
H9B 0.843029 0.174374 0.373348 0.028*
C10 0.98674 (10) 0.21622 (7) 0.45164 (10) 0.0248 (3)
H10A 0.964942 0.228849 0.518104 0.030*
H10B 1.018780 0.162825 0.457622 0.030*
C11 0.94958 (13) 0.38050 (10) −0.09824 (13) 0.0406 (4)
H11A 0.907504 0.419996 −0.142798 0.061*
H11B 0.979557 0.342955 −0.141483 0.061*
H11C 1.006491 0.407029 −0.050283 0.061*
C12 0.76208 (11) 0.26635 (8) −0.10486 (10) 0.0284 (3)
H12A 0.717809 0.241394 −0.061306 0.043*
H12B 0.795342 0.225328 −0.140318 0.043*
H12C 0.718640 0.300404 −0.156636 0.043*

supporting information
sup-3
Acta Cryst. (2021). E77
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
Si1 0.02231 (17) 0.02191 (17) 0.01900 (16) 0.00084 (12) 0.00636 (12) 0.00114 (12)
O1 0.0360 (5) 0.0297 (5) 0.0259 (4) 0.0028 (4) 0.0128 (4) 0.0013 (4)
O2 0.0232 (4) 0.0221 (4) 0.0228 (4) −0.0002 (3) 0.0034 (3) −0.0036 (3)
O3 0.0241 (4) 0.0287 (5) 0.0230 (4) −0.0076 (4) 0.0054 (3) −0.0008 (3)
N1 0.0338 (6) 0.0237 (5) 0.0288 (5) 0.0025 (4) 0.0011 (4) −0.0044 (4)
N2 0.0219 (5) 0.0229 (5) 0.0237 (5) −0.0010 (4) 0.0029 (4) 0.0000 (4)
C1 0.0251 (6) 0.0259 (6) 0.0254 (6) −0.0010 (5) 0.0012 (5) −0.0074 (5)
C2 0.0240 (6) 0.0240 (6) 0.0209 (5) −0.0033 (5) 0.0020 (4) −0.0039 (4)
C3 0.0214 (5) 0.0206 (5) 0.0195 (5) −0.0040 (4) 0.0011 (4) −0.0031 (4)
C4 0.0264 (6) 0.0203 (6) 0.0211 (5) −0.0049 (4) 0.0026 (4) −0.0033 (4)
C5 0.0374 (7) 0.0213 (6) 0.0246 (6) −0.0017 (5) 0.0026 (5) −0.0019 (5)
C6 0.0283 (7) 0.0370 (7) 0.0363 (7) 0.0046 (6) 0.0072 (5) −0.0080 (6)
C7 0.0200 (5) 0.0218 (6) 0.0196 (5) −0.0030 (4) 0.0024 (4) −0.0033 (4)
C8 0.0306 (6) 0.0210 (6) 0.0246 (6) −0.0058 (5) 0.0071 (5) −0.0014 (4)
C9 0.0237 (6) 0.0203 (6) 0.0263 (6) −0.0027 (4) 0.0034 (5) −0.0003 (4)
C10 0.0229 (6) 0.0231 (6) 0.0280 (6) −0.0032 (5) 0.0040 (5) 0.0049 (5)
C11 0.0394 (8) 0.0453 (9) 0.0415 (8) −0.0018 (7) 0.0192 (7) 0.0115 (7)
C12 0.0370 (7) 0.0264 (6) 0.0204 (6) −0.0002 (5) 0.0024 (5) −0.0014 (5)
Geometric parameters (Å, º)
Si1—O2 1.6435 (9) C5—H5 0.9500
Si1—O3i1.6487 (9) C6—H6A 0.9800
Si1—C12 1.8443 (14) C6—H6B 0.9800
Si1—C11 1.8589 (15) C6—H6C 0.9800
O1—C2 1.3539 (15) C7—H7 0.9500
O1—H1 0.90 (2) C8—H8A 0.9900
O2—C8 1.4345 (14) C8—H8B 0.9900
O3—C10 1.4278 (14) C9—C10 1.5168 (17)
N1—C1 1.3343 (18) C9—H9A 0.9900
N1—C5 1.3512 (18) C9—H9B 0.9900
N2—C7 1.2808 (16) C10—H10A 0.9900
N2—C9 1.4631 (16) C10—H10B 0.9900
C1—C2 1.4143 (18) C11—H11A 0.9800
C1—C6 1.5039 (18) C11—H11B 0.9800
C2—C3 1.4041 (17) C11—H11C 0.9800
C3—C4 1.4147 (17) C12—H12A 0.9800
C3—C7 1.4723 (17) C12—H12B 0.9800
C4—C5 1.3832 (18) C12—H12C 0.9800
C4—C8 1.5085 (17)
O2—Si1—O3i103.40 (5) N2—C7—H7 119.4
O2—Si1—C12 106.94 (6) C3—C7—H7 119.4
O3i—Si1—C12 112.06 (6) O2—C8—C4 108.98 (10)
O2—Si1—C11 111.33 (7) O2—C8—H8A 109.9

supporting information
sup-4
Acta Cryst. (2021). E77
O3i—Si1—C11 109.52 (6) C4—C8—H8A 109.9
C12—Si1—C11 113.16 (7) O2—C8—H8B 109.9
C2—O1—H1 104.4 (12) C4—C8—H8B 109.9
C8—O2—Si1 123.61 (8) H8A—C8—H8B 108.3
C10—O3—Si1i123.50 (8) N2—C9—C10 110.90 (10)
C1—N1—C5 118.59 (11) N2—C9—H9A 109.5
C7—N2—C9 118.05 (11) C10—C9—H9A 109.5
N1—C1—C2 121.46 (12) N2—C9—H9B 109.5
N1—C1—C6 118.23 (12) C10—C9—H9B 109.5
C2—C1—C6 120.30 (12) H9A—C9—H9B 108.0
O1—C2—C3 122.14 (11) O3—C10—C9 109.10 (10)
O1—C2—C1 117.91 (11) O3—C10—H10A 109.9
C3—C2—C1 119.92 (11) C9—C10—H10A 109.9
C2—C3—C4 117.69 (11) O3—C10—H10B 109.9
C2—C3—C7 120.63 (11) C9—C10—H10B 109.9
C4—C3—C7 121.57 (11) H10A—C10—H10B 108.3
C5—C4—C3 118.12 (12) Si1—C11—H11A 109.5
C5—C4—C8 119.45 (11) Si1—C11—H11B 109.5
C3—C4—C8 122.36 (11) H11A—C11—H11B 109.5
N1—C5—C4 124.19 (12) Si1—C11—H11C 109.5
N1—C5—H5 117.9 H11A—C11—H11C 109.5
C4—C5—H5 117.9 H11B—C11—H11C 109.5
C1—C6—H6A 109.5 Si1—C12—H12A 109.5
C1—C6—H6B 109.5 Si1—C12—H12B 109.5
H6A—C6—H6B 109.5 H12A—C12—H12B 109.5
C1—C6—H6C 109.5 Si1—C12—H12C 109.5
H6A—C6—H6C 109.5 H12A—C12—H12C 109.5
H6B—C6—H6C 109.5 H12B—C12—H12C 109.5
N2—C7—C3 121.19 (11)
O3i—Si1—O2—C8 68.47 (10) C2—C3—C4—C8 −176.10 (11)
C12—Si1—O2—C8 −173.10 (9) C7—C3—C4—C8 0.08 (17)
C11—Si1—O2—C8 −49.03 (11) C1—N1—C5—C4 0.17 (19)
C5—N1—C1—C2 1.61 (18) C3—C4—C5—N1 −1.42 (19)
C5—N1—C1—C6 −176.99 (12) C8—C4—C5—N1 175.64 (12)
N1—C1—C2—O1 179.60 (11) C9—N2—C7—C3 178.48 (10)
C6—C1—C2—O1 −1.83 (17) C2—C3—C7—N2 −3.14 (17)
N1—C1—C2—C3 −2.09 (18) C4—C3—C7—N2 −179.21 (11)
C6—C1—C2—C3 176.48 (11) Si1—O2—C8—C4 −154.64 (8)
O1—C2—C3—C4 179.01 (11) C5—C4—C8—O2 −106.34 (13)
C1—C2—C3—C4 0.78 (17) C3—C4—C8—O2 70.59 (14)
O1—C2—C3—C7 2.80 (17) C7—N2—C9—C10 108.51 (12)
C1—C2—C3—C7 −175.43 (10) Si1i—O3—C10—C9 143.92 (9)
C2—C3—C4—C5 0.87 (16) N2—C9—C10—O3 −65.04 (13)
C7—C3—C4—C5 177.05 (11)
Symmetry code: (i) −x+2, y, −z+1/2.

supporting information
sup-5
Acta Cryst. (2021). E77
Hydrogen-bond geometry (Å, º)
Cg1 is the centroid of the N1/C1–C5 ring.
D—H···AD—H H···AD···AD—H···A
O1—H1···N2 0.90 (2) 1.76 (2) 2.5923 (15) 153.2 (18)
C5—H5···O1ii 0.95 2.69 3.5451 (16) 151
C6—H6A···O2iii 0.98 2.59 3.3464 (17) 134
C7—H7···O3i0.95 2.57 3.4882 (15) 162
C9—H9B···O2iv 0.99 2.60 3.5087 (16) 153
C9—H9B···Cg1iv 0.99 3.31 4.039 (2) 131
C11—H11A···Cg1ii 0.98 2.85 3.7880 (2) 160
Symmetry codes: (i) −x+2, y, −z+1/2; (ii) x, −y+1, z−1/2; (iii) x, −y+1, z+1/2; (iv) −x+3/2, −y+1/2, −z+1/2.