Neutral hexacoordinate silicon(IV) complexes with a SiO4NC or SiO3N2C skeleton and neutral pentacoordinate silicon(IV) complexes containing a trianionic tetradentate O,N,O,O ligand

Article abstract of DOI:10.1002/ejic.201301185

A series of neutral hexacoordinate silicon(IV) complexes with a SiO ₄NC or SiO₃N₂C skeleton was synthesized. Additionally, two neutral pentacoordinate silicon(IV) complexes with a SiO ₃NC skeleton were synthesized. All compounds studied were structurally characterized by multinuclear NMR spectroscopy in the solid state and in solution and by single-crystal X-ray diffraction. The hexacoordinate compounds studied contain a tridentate dianionic O,N,O or N,N,O ligand, a phenyl ligand, and a symmetrically substituted derivative of an acetylacetonato ligand of the formula type RC(O)-CH=C(OSiMe₃)R (R = Me, Ph, CF ₃). The two pentacoordinate complexes contain a tetradentate trianionic O,N,O,O ligand and a phenyl ligand. Copyright

Full text of DOI:10.1002/ejic.201301185

FULL PAPER
DOI:10.1002/ejic.201301185
Neutral Hexacoordinate Silicon(IV) Complexes with a
SiO4NC or SiO3N2C Skeleton and Neutral
Pentacoordinate Silicon(IV) Complexes Containing a
Trianionic Tetradentate O,N,O,O Ligand
Jörg Weiß,[a] Katharina Sinner,[a] Johannes A. Baus,[a]
Christian Burschka,[a] and Reinhold Tacke*[a]
Keywords: Acetylacetone / Bidentate ligands / Coordination modes / Silicon / Tridentate ligands
A series of neutral hexacoordinate silicon(IV) complexes with
a SiO4NC or SiO3N2C skeleton was synthesized. Addition-
ally, two neutral pentacoordinate silicon(IV) complexes with
a SiO3NC skeleton were synthesized. All compounds studied
were structurally characterized by multinuclear NMR spec-
troscopy in the solid state and in solution and by single-crys-
tal X-ray diffraction. The hexacoordinate compounds studied
contain a tridentate dianionic O,N,O or N,N,O ligand, a
phenyl ligand, and a symmetrically substituted derivative of
an acetylacetonato ligand of the formula type RC(O)–CH=C-
(OSiMe3)R (R = Me, Ph, CF3). The two pentacoordinate com-
plexes contain a tetradentate trianionic O,N,O,O ligand and
a phenyl ligand.
Introduction
In a series of recent publications, we have reported on
the synthesis of the neutral pentacoordinate silicon(IV)
complexes 1–3 (S/O/NMe analogues) and their use in the
preparation of further neutral pentacoordinate silicon(IV)
complexes that contain other monoanionic monodentate li-
gands instead of the chlorido ligand.[1] These studies were
performed with a special focus on the comparison of the
respective S/O/NMe analogues, some of which differ signifi-
cantly in their chemical properties.
In addition, we have also reported on the transformation
of 1 into the neutral hexacoordinate silicon(IV) complexes
4a and 4b.[2] These syntheses represent two rare examples
for the use of neutral pentacoordinate silicon(IV) complexes
as starting materials for the preparation of neutral hexaco-
ordinate silicon(IV) complexes.
In continuation of these studies, we have now synthesized
the respective S/O and S/NMe analogues of 4a and 4b, com-
pounds 5a, 5b, 6a, and 6b. Attempts to prepare the related
S/O/NMe analogues 4c, 5c, and 6c by using the same syn-
thetic method failed. Instead, we obtained the neutral
pentacoordinate silicon(IV) complexes 4cЈ, 5cЈ, and 6cЈ. We
report here on the syntheses of compounds 4cЈ, 5a, 5b, 5cЈ,
6a, 6b, and 6cЈ and their characterization by NMR spectro-
scopic studies in the solid state and in solution and by crys-
[a] Universität Würzburg, Institut für Anorganische Chemie,
Am Hubland, 97074 Würzburg, Germany
E-mail: r.tacke@uni-wuerzburg.de
http://www-anorganik.chemie.uni-wuerzburg.de/
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tal structure analyses. These investigations were performed tion of an analogous rearrangement product.[2] The forma-
as part of our ongoing systematic studies on higher-coordi- tion of 4cЈ and 6cЈ can be explained starting with the first
nate silicon(IV) complexes.[3–5]
step giving the expected products 4c and 6c, followed by
cleavage of the Si–S and Si–N(amido) bond, respectively,
and intramolecular formation of the new S–C or N–
C bond. This rearrangement results in the formation of a
new tetradentate trianionic O,N,O,O ligand in the silicon
coordination sphere. The coordination of this ligand to the
silicon atom leads to a tetracyclic ring system consisting of
two six-membered rings, one seven-membered ring, and one
nine-membered ring. The silicon atom and one of the two
CF3-bound carbon atoms represent the two bridgehead
atoms of this tetracyclic ring system. The assumption that
4c and 6c are intermediates in the formation of 4cЈ and 6cЈ,
respectively, is supported by the color change observed for
the two reaction mixtures. The solution of 1 in acetonitrile
is yellow, and upon addition of the pale yellow reagent 9
initially an orange-colored mixture was formed. Likewise,
the solution of 3 in acetonitrile is orange-colored, and upon
addition of 9 a dark-red solution was observed. In both
cases, after a short period of time, the reaction mixtures
then turned to pale yellow solutions, and upon storage at
–20 °C for one day colorless crystals of 4cЈ·0.5C6H5CH3
and 6cЈ were obtained.
Results and Discussion
Syntheses
Compounds 5a, 5b, 6a, and 6b were synthesized accord-
ing to Scheme 1 by treatment of the chlorosilicon(IV) com-
plexes 2 and 3 with the respective silylated acetylacetone
derivatives of the formula type RC(O)–CH=C(OSiMe3)R
(7: R = Me; 8: R = Ph). All syntheses were carried out in
acetonitrile at 20 °C, and compounds 5a, 5b, 6a, and 6b
were isolated as crystalline solids (colors and yields:
5a·0.5CH3CN, yellow, 76%; 5b·CH3CN, orange, 85%;
6a·CH3CN, dark-red, 69%; 6b·CH3CN, dark-red, 44%).
Scheme 1. Synthesis of compounds 5a, 5b, 6a, and 6b.
Compound 5cЈ was synthesized according to Scheme 2
by reaction of the chlorosilicon(IV) complex 2 with
CF3C(O)–CH=C(OSiMe3)CF3 (9) in diethyl ether at 20 °C
and was isolated as a red crystalline solid in 78% yield.[6]
In contrast to the formation of 5a and 5b (Ǟ hexacoordina-
tion), the reaction of 2 with 9 stops at the pentacoordinate
stage (5cЈ) (see “Crystal Structure Analyses”).
Scheme 3. Synthesis of compounds 4cЈ and 6cЈ.
The different chemical behavior of compounds 4a, 4b,
5a, 5b, 6a, and 6b (no rearrangement) compared to that of
4c and 6c (rearrangement) can be explained by the presence
of the CF3 groups in the latter two compounds. The
strongly electron-withdrawing CF3 groups increase the elec-
trophilicity of the carbon atoms next to the CF3 groups,
assisting the nucleophilic attack of the sulfur and nitrogen
ligand atom of 4c and 6c, respectively, to give the rearrange-
ment products 4cЈ and 6cЈ.
Scheme 2. Synthesis of compound 5cЈ.
Compounds 4cЈ and 6cЈ were synthesized according to
Scheme 3 by treatment of the chlorosilicon(IV) complexes
1 and 3, respectively, with 9. The syntheses were carried out
in acetonitrile at 20 °C, and 4cЈ and 6cЈ were isolated, after
crystallization from toluene, as colorless crystalline solids
(yields: 4cЈ·0.5C6H5CH3, 63%; 6cЈ, 51%). Interestingly, the
expected hexacoordinate silicon(IV) complexes 4c and 6c
could not be obtained; instead, the pentacoordinate re-
arrangement products 4cЈ and 6cЈ were isolated. Treatment
Crystal Structure Analyses
Compounds
4cЈ·0.5C6H5CH3,
5a·0.53CH3CN,
of 1 with PhC(O)–CH=C(OSiMe3)CF3 resulted in the forma- 5b·CH3CN, 5cЈ·(C2H5)2O, 6a, 6b·CH3CN, and 6cЈ were
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Table 1. Crystallographic data for compounds 4cЈ·0.5C6H5CH3, 5a·0.53CH3CN, 5b·CH3CN, 5cЈ·(C2H5)2O, 6a, 6b·CH3CN, and 6cЈ.
4cЈ·0.5C6H5CH3
5a·0.53CH3CN
5b·CH3CN
5cЈ·(C2H5)2O
6a
6b·CH3CN
6cЈ
Empirical formula C22H17F6NO3SSi· C22H23NO4Si·
C32H27NO4Si·
CH3CN
558.69
C22H17F6NO4Si· C23H26N2O3Si C35H33N3O3Si· C23H20F6N2O3Si
0.5C6H5CH3
563.58
173(2)
0.53CH3CN
415.21
100(2)
(C2H5)2O
575.58
173(2)
0.71073
monoclinic
P21/c (14)
10.8309(18)
13.033(2)
19.248(3)
90
CH3CN
571.73
173(2)
Mr
T [K]
406.55
173(2)
0.71073
monoclinic
P21/c (14)
8.4805(13)
15.143(3)
16.710(2)
90
93.445(18)
90
2141.9(6)
4
514.50
173(2)
0.71073
monoclinic
P21/n (14)
10.878(2)
13.1457(19)
16.012(3)
90
93.58(3)
90
2285.3(8)
4
100(2)
λ(Mo-Kα) [Å]
Crystal system
Space group (no.) P1 (2)
a [Å]
b [Å]
c [Å]
α [°]
β [°]
0.71073
triclinic
0.71073
monoclinic
P21 (4)
11.7786(17)
23.476(3)
15.793(2)
90
90.205(7)
90
4366.9(11)
8
0.71073
triclinic
0.71073
triclinic
¯
¯
¯
P1 (2)
P1 (2)
11.8529(17)
10.0010(7)
12.4225(9)
12.8603(10)
111.202(2)
97.313(2)
102.624(2)
1415.70(18)
2
10.119(2)
12.055(3)
13.764(3)
69.33(3)
83.80(3)
72.37(3)
1497.2(6)
2
12.2558(18)
18.634(3)
80.423(17)
76.044(16)
79.184(17)
2559.3(7)
4
1.463
0.246
1156
90.327(19)
90
2716.9(7)
4
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3]
μ [mm–1]
F(000)
1.263
0.137
1757
1.311
0.126
588
1.407
1.261
1.268
1.495
0.164
0.136
0.119
0.181
1192
864
604
1056
Dimensions [mm] 0.8ϫ0.5ϫ0.4
0.37ϫ0.31ϫ0.26 0.5ϫ0.4ϫ0.15 0.6ϫ0.5ϫ0.4 0.7ϫ0.3ϫ0.3 0.75ϫ0.55ϫ0.3 0.7ϫ0.5ϫ0.25
2θ [°]
Index ranges
5.14–52.04
–14Յ hՅ 14,
–15Յ kՅ 15,
–22Յ lՅ 22
27898
2.58–56.55
–15Յ hՅ 15,
–31Յ kՅ 31,
–21Յ lՅ 20
97045
3.48–61.00
–14Յ hՅ 14,
–17Յ kՅ 17,
–17Յ lՅ 18
57658
5.26–52.04
–13Յ hՅ 13,
–16Յ kՅ 16,
–23Յ lՅ 23
24547
5.52–52.04
–10Յ hՅ 10,
–18Յ kՅ 18,
–20Յ lՅ 20
23060
4.80–52.04
–12Յ hՅ 12,
–14Յ kՅ 14,
–16Յ lՅ 16
20042
5.96–52.04
–13Յ hՅ 13,
–15Յ kՅ 16,
–19Յ lՅ 19
24407
No. reflns. coll.
No. indep. reflns.
Rint.
9407
0.0666
21465
0.0459
8553
0.0263
5328
0.0412
4031
0.0409
5511
0.0417
4463
0.0439
No. of restraints
No. of param.
S[a]
0
681
1.105
64
1112
1.104
0.0553/2.3679
0.0456
0
373
1.012
0.0538/0.6631
0.0369
36
401
1.053
0.0679/1.3915
0.0464
0
267
1.044
0.0434/0.7221
0.0362
0
383
1.039
0.0523/0.2807
0.0354
0
319
1.067
0.0605/0.5755
0.0367
Wt. param. a/b[b] 0.0730/1.4813
R1[c] [IϾ2σ(I)]
0.0513
0.1471
[d]
wR2 (all data)
0.1183
0.1039
0.1266
0.0947
0.0963
0.1034
Absol. str. param.
0.04(2)
+0.701/–0.313
Δρmax./min. [eÅ–3]
+0.635/–0.401
+0.507/–0.300
+0.507/–0.371 +0.266/–0.254 +0.313/–0.240
+0.486/–0.313
[a] S = {Σ [w(Fo – Fc ) ]/(n – p)}0.5; n = number of reflections; p = number of parameters. [b] w–1 = σ2(Fo2) + (aP)2 + bP, with P =
2
2 2
2
2
2 2
[max(Fo2,0) + 2Fc ]/3. [c] R1 = Σ ||Fo| – |Fc||/Σ |Fo|. [d] wR2 = {Σ [w(Fo – Fc ) ]/Σ [w(Fo2)2]}0.5
.
structurally characterized by single-crystal X-ray diffrac- respectively, and the corresponding Si–N(amido) distances
tion. The crystal data and experimental parameters used for of 6a and 6b range from 1.8172(14) to 1.8249(13) Å. The
the crystal structure analyses are given in Table 1. Com- Si–N(imino) bond lengths of 5a, 5b, 6a, and 6b are in the
pounds 4cЈ·0.5C6H5CH3 and 5a·0.53CH3CN crystallized range 1.9075(8)–1.957(3) Å, and the Si–C bond lengths are
with two and four silicon(IV) complexes, respectively, in the 1.924(3)–1.9383(16) Å. Generally, the structures of 5a, 5b,
asymmetric unit. The molecular structures of 4cЈ, 5a, 5b, 6a, and 6b are very similar and compare well with those of
5cЈ, 6a, 6b, and 6cЈ are shown in Figures 1, 2, 3, 4, 5, 6, and 4a and 4b. Obviously, the three different tridentate S,N,O,
7, respectively, with selected bond lengths and angles in the O,N,O, and N,N,O ligands and the two different bidentate
captions.
O,O ligands have only little impact on the structures of the
The silicon coordination polyhedra of 5a, 5b, 6a, and 6b S/O/NMe analogues 4a/5a/6a and 4b/5b/6b.
are best described as distorted octahedra. The maximum
The silicon coordination polyhedron of 5cЈ is best de-
deviations from the ideal 180 and 90° angles range from scribed as a slightly distorted square pyramid, with the car-
7.97(4) to 9.82(12)° and from 6.46(13) to 7.58(10)°, respec- bon atom in the apical position and a Berry distortion[8]
tively. The tridentate O,N,O and N,N,O ligands show mer (transition trigonal bipyramid Ǟ square pyramid) of
coordination, with O1–Si–O4 angles ranging from 94.0%. The O1–Si–O4 and O3–Si–N angles are 158.48(8)
170.18(12) to 172.03(4)° and O1–Si–N2 angles in the range and 163.32(8)°, respectively. The three Si–O bond lengths
170.58(6)–172.09(5)°. The Si–O1 [1.765(2)–1.7896(13) Å] (Si–O1, Si–O3, Si–O4) range from 1.7210(16) to
and Si–O3 [1.7802(12)–1.8064(13) Å] bond lengths of 5a, 1.7803(16) Å, and the Si–N and Si–C distances are
5b, 6a, and 6b are similar, whereas differences were ob- 1.8961(18) and 1.889(2) Å, respectively. The bond angles
served for the Si–O2 bond lengths. The Si–O2 bond dis- and lengths reported above and the long Si···O2 distance
tances of 5a/5b [1.860(2)–1.902(2)/1.8602(7) Å; O,N,O li- (2.333 Å) suggest pentacoordination of the silicon atom of
gand] are significantly shorter than those of 6a/6b 5cЈ. Alternatively, the coordination mode might be dis-
[1.9266(11)/1.9032(11) Å; N,N,O ligand]. The Si–O4 bond cussed in terms of a [5+1] coordination, with a base-capped
lengths of 5a and 5b are 1.745(2)–1.763(2) and 1.7612(7) Å, square pyramid as the coordination polyhedron. However,
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Figure 1. Molecular structure of one of the two crystallographically
independent molecules in the crystal of 4cЈ·0.5C6H5CH3 (prob-
ability level of displacement ellipsoids 50%). Selected bond lengths
[Å] and angles [°]: Si1–O1 1.800(2), Si1–O2 1.739(2), Si1–O3
1.705(2), Si1–N1 1.828(2), Si1–C1 1.886(3); O1–Si1–O2 176.73(10);
O1–Si1–O3 83.89(10), O1–Si1–N1 90.21(10), O1–Si1–C1 88.83(11),
O2–Si1–O3 93.28(10), O2–Si1–N1 92.47(10), O2–Si1–C1 91.54(11),
O3–Si1–N1 114.55(10), O3–Si1–C1 126.24(11), N1–Si1–C1
118.68(11). The structure of the second molecule is very similar
and behaves, as a first approximation, as a mirror image.
Figure 3. Molecular structure of 5b in the crystal of 5b·CH3CN
(probability level of displacement ellipsoids 50%). Selected bond
lengths (Å) and angles (°): Si–O1 1.7857(7), Si–O2 1.8602(7), Si–
O3 1.7837(7), Si–O4 1.7612(7), Si–N1 1.9075(8), Si–C1 1.9254(10);
O1–Si–O2 84.10(3), O1–Si–O3 89.75(3), O1–Si–O4 172.03(4), O1–
Si–N1 91.47(3), O1–Si–C1 93.41(4), O2–Si–O3 89.18(3), O2–Si–O4
88.16(3), O2–Si–N1 84.32(3), O2–Si–C1 177.34(4), O3–Si–O4
92.07(3), O3–Si–N1 173.23(4), O3–Si–C1 89.88(4), O4–Si–N1
85.84(3), O4–Si–C1 94.36(4), N1–Si–C1 96.70(4).
Figure 2. Molecular structure of one of the four crystallographi-
cally independent molecules in the crystal of 5a·0.53CH3CN (prob-
ability level of displacement ellipsoids 50%). Selected bond lengths
[Å] and angles [°]: Si1–O1 1.770(2), Si1–O2 1.860(2), Si1–O3
1.805(2), Si1–O4 1.763(2), Si1–N1 1.928(3), Si1–C1 1.924(3); O1–
Si1–O2 84.30(11), O1–Si1–O3 89.42(11), O1–Si1–O4 171.96(12),
O1–Si1–N1 93.46(11), O1–Si1–C1 93.73(13), O2–Si1–O3 90.21(11),
O2–Si1–O4 87.67(11), O2–Si1–N1 83.43(11), O2–Si1–C1
Figure 4. Molecular structure of 5cЈ in the crystal of 5cЈ·(C2H5)2O
(occupation factor 63%;[7] probability level of displacement ellip-
soids 50%). Selected bond lengths [Å] and angles [°]: Si–O1
1.7382(16), Si–O3 1.7803(16), Si–O4 1.7210(16), Si–N 1.8961(18),
177.33(12), O3–Si1–O4 90.17(11), O3–Si1–N1 172.71(12), O3–Si1– Si–C1 1.889(2); O1–Si–O3 86.27(7), O1–Si–O4 158.48(8), O1–Si–N
C1 91.57(12), O4–Si1–N1 86.05(11), O4–Si1–C1 94.32(12), N1–
Si1–C1 94.92(12). The structures of the three other molecules are
very similar.
92.43(8), O1–Si–C1 100.64(9), O3–Si–O4 88.58(7), O3–Si–N
163.32(8), O3–Si–C1 96.50(8), O4–Si–N 86.57(7), O4–Si–C1
100.70(9), N–Si–C1 100.07(9).
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Figure 5. Molecular structure of 6a in the crystal (probability level
of displacement ellipsoids 50%). Selected bond lengths [Å] and
angles [°]: Si–O1 1.7896(13), Si–O2 1.9266(11), Si–O3 1.7802(12),
Si–N1 1.9275(14), Si–N2 1.8172(14), Si–C1 1.9383(16); O1–Si–O2
82.87(5), O1–Si–O3 88.10(6), O1–Si–N1 92.10(6), O1–Si–N2
170.58(6), O1–Si–C1 92.71(6), O2–Si–O3 90.16(5), O2–Si–N1
83.53(5), O2–Si–N2 87.95(6), O2–Si–C1 175.09(6), O3–Si–N1
173.61(5), O3–Si–N2 94.05(6), O3–Si–C1 91.81(6), N1–Si–N2
84.74(6), N1–Si–C1 94.56(6), N2–Si–C1 96.39(6).
Figure 7. Molecular structure of 6cЈ in the crystal (probability level
of displacement ellipsoids 50%). Selected bond lengths [Å] and
angles [°]: Si–O1 1.8013(12), Si–O2 1.7257(12), Si–O3 1.6994(12),
Si–N1 1.8267(14), Si–C1 1.8940(17); O1–Si–O2 178.55(5), O1–Si–
O3 84.59(6), O1–Si–N1 89.55(6), O1–Si–C1 89.52(6), O2–Si–O3
94.28(6), O2–Si–N1 90.04(6), O2–Si–C1 91.84(6), O3–Si–N1
112.08(6), O3–Si–C1 120.51(7), N1–Si–C1 127.04(7).
there is no clear experimental evidence for a long-range in-
teraction between the silicon coordination center and the
oxygen atom O2 (in this context, see also the section “NMR
Spectroscopic Studies”). Nevertheless, the molecular struc-
tures of the hexacoordinate compounds 5a and 5b and the
pentacoordinate compound 5cЈ are related to each other
since the Si–O2 bonds of 5a [1.860(2) Å] and 5b
[1.8602(7) Å] are significantly longer than the Si–O1 bonds
of these compounds [5a 1.770(2) Å, 5b 1.7857(7) Å]. This
indicates a pronounced localization of the negative charge
of the acetylacetonato ligand at one of the two oxygen
atoms of 5a and 5b, and compound 5cЈ appears to be a
rather striking case of this charge localization, leading to a
much stronger Si–O2 bond weakening or even an almost
complete loss of bonding interaction (Si···O2 2.333 Å).
The silicon coordination polyhedra of 4cЈ and 6cЈ are
best described as slightly distorted trigonal bipyramids,
with the oxygen atoms O1 and O2 in the axial positions.
The Berry distortions[8] are 14.4/16.1 and 11.9%, respec-
tively. The maximum deviations from the ideal 180° angles
are 3.61(10) (4cЈ) and 1.45(5)° (6cЈ), and the maximum devi-
ations from the ideal 120° angles are 6.86(11) (4cЈ) and
7.92(6)° (6cЈ). The axial Si–O bond distances of 4cЈ and 6cЈ
[1.7257(12)–1.8013(12) Å] are somewhat longer than those
of the equatorial ones [1.6994(12)–1.708(2) Å]. The Si–N
distances are 1.828(2)/1.838(2) (4cЈ) and 1.8267(14) Å (6cЈ),
and Si–C bond lengths range from 1.886(3)/1.877(3) (4cЈ)
to 1.8940(17) Å (6cЈ). Generally, the structural features of
the S/NMe analogues 4cЈ and 6cЈ are very similar.
Figure 6. Molecular structure of 6b in the crystal of 6b·CH3CN
(probability level of displacement ellipsoids 50%). Selected bond
lengths [Å] and angles [°]: Si–O1 1.7839(11), Si–O2 1.9032(11), Si–
O3 1.8064(13), Si–N1 1.9099(14), Si–N2 1.8249(13), Si–C1
1.9346(15); O1–Si–O2 83.60(5), O1–Si–O3 88.07(6), O1–Si–N1
92.02(6), O1–Si–N2 172.09(5), O1–Si–C1 93.33(6), O2–Si–O3
87.67(5), O2–Si–N1 82.82(5), O2–Si–N2 88.96(5), O2–Si–C1
176.93(5), O3–Si–N1 170.42(5), O3–Si–N2 94.33(6), O3–Si–C1
92.17(6), N1–Si–N2 84.37(6), N1–Si–C1 97.39(6), N2–Si–C1
94.11(6).
Eur. J. Inorg. Chem. 2014, 475–483
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NMR Spectroscopic Studies
Compounds 4cЈ·0.5C6H5CH3,
complexes with SiSO3NC (4a, 4b), SiO4NC (5a, 5b), or
SiO3N2 skeletons (6a, 6b). The silicon complexes 4a and 4b
have already been described earlier, whereas 5a, 5b, 6a, and
6b represent new types of hexacoordinate silicon(IV) com-
plexes. The S/O/NMe analogues 4a/5a/6a and 4b/5b/6b
show an analogous stereochemistry in the solid state. The
silicon coordination polyhedron is a distorted octahedron,
with the tridentate S,N,O, O,N,O, or N,N,O ligand in mer
positions. For compounds 6a and 6b (NMe series), a dy-
namic behavior in solution was observed (dynamic of the
O,O ligand), whereas 4a and 4b (S series) and 5a and 5b (O
series) do not show such behavior.
5a·0.5CH3CN,
5b·CH3CN, 5cЈ·(C2H5)2O, 6a, 6b·CH3CN, and 6cЈ were
studied by NMR spectroscopy in the solid state (15N, 29Si)
1
and in solution (solvent: CD2Cl2; H, 13C, 19F, 29Si). The
isotropic 29Si chemical shifts in the solid state clearly indi-
cate the presence of pentacoordinate (4cЈ–6cЈ) or hexacoor-
dinate (5a, 5b, 6a, 6b) silicon atoms (Table 2). These chemi-
cal shifts are very similar to those obtained in solution
(Table 2), indicating that all compounds studied exist in
solution as well.
Table 2. Isotropic 29Si chemical shifts of 4cЈ, 5a, 5b, 5cЈ, 6a, 6b, and
6cЈ in the solid state (T = 22 °C) and in solution (solvent: CD2Cl2;
T = 23 °C).
Compounds 1–3 have also been demonstrated to be valu-
able precursors for the preparation of neutral pentacoordi-
nate silicon(IV) complexes, compounds 4cЈ–6cЈ. Com-
pounds 4a–6a, 4b–6b, and 4cЈ–6cЈ were all obtained by
treatment of 1–3 with the corresponding silylated acetyl-
acetone derivatives RC(O)–CH=C(OSiMe3)R (R = Me, Ph,
CF3; elimination of Me3SiCl). In these reactions, the nature
of the R group of the silylated acetylacetone derivative con-
trols the product formation. In the case of R = CF3, the
expected hexacoordinate products 4c–6c could not be ob-
served; instead, the pentacoordinate compound 4cЈ–6cЈ
were obtained. Compound 5cЈ contains a square-pyramidal
silicon coordination polyhedron, whereas 4cЈ and 6cЈ con-
tain a trigonal-bipyramidal structure. This is another inter-
esting example of the striking differences of S/O/NMe ana-
logues derived from 1–3 (in this context, see also ref.[1,2]).
The formation of 4cЈ and 6cЈ represents a remarkable exam-
ple of the generation of a new tetradentate trianionic
O,N,O,O ligand in the silicon coordination sphere, probably
by rearrangement of the potential intermediates 4c and 6c.
As a result, tetracyclic ring systems consisting of two six-
membered rings, one seven-membered ring, and one nine-
membered ring are built up.
Compound
δ29Si (solid state) [ppm] δ29Si (solution) [ppm]
4cЈ
–124.5[a]
–125.3
–165.1
5a
–168.1, –167.2, –166.1,
–165.8[b]
5b
5cЈ
6a
6b
6cЈ
–164.3[c]
–164.2
–133.2
–162.0
–161.1
–124.2
–134.4[d]
–163.4
–161.5[e]
–127.7
[a] Solvate 4cЈ·0.5C6H5CH3. [b] Solvate 5a·0.5CH3CN; four crystal-
lographically independent molecules. [c] Solvate 5b·CH3CN. [d]
Solvate 5cЈ·(C2H5)2O. [e] Solvate 6b·CH3CN.
The solution 1H and 13C NMR spectroscopic studies
(solvent: CD2Cl2) revealed a major difference between the
S/O/NMe analogues 4a/5a/6a and 4b/5b/6b. Compounds 6a
and 6b (NMe series) showed a dynamic behavior at room
temperature [one set of resonance signals each for the two
RC(O) groups of the bidentate O,O ligands], whereas
this kind of behavior was not observed for 4a and 4b
(S series)[2] and 5a and 5b (O series). This observation can
be correlated with the longer Si–O2 bond distances (see
“Crystal Structure Analyses”) in the NMe series [6a
1.9266(11) Å, 6b 1.9032(11) Å] compared to those in the O
series [5a 1.860(2) Å, 5b 1.8602(7) Å] and the S series [4a
1.8505(16) Å, 4b 1.8492(10) Å].[2] These longer Si–O2 dis-
tances in 6a and 6b may reflect a weaker bonding of the
acetylacetonato ligand to the silicon coordination center
and could explain the higher mobility of the bidentate O,O
ligands of 6a and 6b.
In conclusion, the results reported here again emphasize
the high synthetic potential of the S/O/NMe analogues 1–3
for the chemistry of penta- and hexacoordinate silicon(IV)
complexes.
Experimental Section
General Procedures: All syntheses were carried out under dry ar-
gon. The organic solvents used were dried and purified according
to standard procedures and stored under argon. The solution-state
1H, 13C, 19F, and 29Si NMR spectra were recorded at 23 °C by
using a Bruker Avance 400 (19F, 376.5 MHz) or Bruker Avance 500
NMR spectrometer (1H, 500.1 MHz; 13C, 125.8 MHz; 29Si,
99.4 MHz). CD2Cl2 served as the solvent. Chemical shifts were de-
termined relative to internal CHDCl2 (1H, δ = 5.32 ppm), CD2Cl2
(13C, δ = 53.8 ppm), or external TMS (29Si, δ = 0 ppm). Assignment
of the 13C NMR spectroscopic data was supported by DEPT 135
and 13C,1H correlation experiments. Solid-state 15N and 29Si VACP/
MAS NMR spectra were recorded at 22 °C by using a Bruker
DSX-400 NMR spectrometer with bottom layer rotors of ZrO2
(diameter, 7 mm) containing about 300 mg of sample [15N,
40.6 MHz; 29Si, 79.5 MHz; external standard, TMS (29Si, δ =
Compound 5cЈ also shows a dynamic behavior in solu-
tion (solvent: CD2Cl2). At room temperature, only one 19F
and one 13C resonance signal for the two CF3 groups were
observed, and the 13C NMR signal for the two oxygen-
–
bound carbon atoms of the CF3C(O)=CH–C(O)CF3 li-
1
gand could not be detected. In contrast, the H, 13C, and
19F NMR spectra of compounds 4cЈ and 6cЈ do not indicate
any dynamic behavior.
Conclusions
The neutral pentacoordinate chlorosilicon(IV) complexes
1–3 have been demonstrated to be suitable starting materi-
als for the synthesis of neutral hexacoordinate silicon(IV) 0 ppm) or glycine (15N, δ = –342.0 ppm); spinning rate, 5 kHz; con-
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tact time, 3 ms (15N) or 5 ms (29Si); 90° 1H transmitter pulse length,
3.6 μs; repetition time, 4–7 s].
to 20 °C (formation of crystals) and kept undisturbed at this tem-
perature for 3 h and then at –20 °C for a further 15 h. The resulting
precipitate was isolated by filtration, washed with n-pentane
(10 mL), and dried in vacuo (0.01 mbar, 20 °C, 4 h) to give
5b·CH3CN in 85% yield (781 mg, 1.40 mmol) as an orange-colored
crystalline solid. 1H NMR (CD2Cl2): δ = 1.88 (s, 3 H, CCH3), 1.97
(s, 3 H, CH3CN), 2.45 (s, 3 H, CCH3), 5.25 (s, 1 H, CCHC), 7.12
(s, 1 H, CCHC), 6.63–6.74, 7.11–7.29, 7.37–7.75, 8.00–8.06 (m, 19
H, OC6H4N, SiC6H5, CC6H5) ppm. 13C NMR (CD2Cl2): δ = 2.0
(CH3CN), 23.9 (CCH3), 24.8 (CCH3), 94.8 (CCHC), 102.6
(CCHC), 117.4 (CH3CN), 115.4, 121.0, 126.2, 126.5 (2 C), 127.8,
128.4 (2 C), 128.6 (2 C), 128.9 (2 C), 129.0, 129.1 (2 C), 133.3,
133.4, 133.5, 134.7 (2 C), 135.8, 136.5, 153.0, 156.3 (OC6H4N,
SiC6H5, CC6H5), 168.0 [C(N)CH3], 177.2 [C(O)CH3], 182.8
[C(O)C6H5], 184.7 [C(O)C6H5] ppm. 29Si NMR (CD2Cl2): δ =
–164.2 ppm. 15N VACP/MAS NMR: δ = –177.3 [C(N)CH3], –126.1
4cЈ·0.5C6H5CH3: 1,1,1,5,5,5-Hexafluoro-4-(trimethylsilyloxy)pent-
3-en-2-one (2.07 g, 7.39 mmol) was added in a single portion at
20 °C to a stirred mixture of 1 (2.13 g, 6.16 mmol) and acetonitrile
(50 mL), and the reaction mixture was then stirred at this tempera-
ture for 1 h. All volatile components were removed in vacuo, tolu-
ene (20 mL) was added to the residue, and the resulting mixture
was heated until a clear solution was obtained, which was cooled
slowly to –20 °C and then kept undisturbed at this temperature for
17 h. The resulting precipitate was isolated by filtration, washed
with n-pentane (10 mL), and dried in vacuo (0.01 mbar, 20 °C, 2 h)
to give 4cЈ·0.5C6H5CH3 in 63% yield (2.19 g, 3.89 mmol) as a col-
orless crystalline solid. 1H NMR (CD2Cl2): δ = 1.78 (s, 3 H,
CCH3), 2.29 (s, 3 H, CCH3), 2.35 (m, 1.5 H, C6H5CH3), 5.79 (s, 1
H, CCHC), 5.87 (s, 1 H, CCHC), 6.94–6.99, 7.13–7.20, 7.23–7.30,
7.31–7.36, 7.36–7.40, 7.64–7.68, 7.69–7.73 (m, 11.5 H, SC6H4N,
SiC6H5, C6H5CH3) ppm. 13C NMR (CD2Cl2): δ = 21.5 (0.5 C,
C6H5CH3), 24.9 (CCH3), 25.0 (CCH3), 83.7 [q, 2J(13C,19F) =
32.5 Hz, CCF3], 102.6 (CCHC), 102.9 [q, 3J(13C,19F) = 1.9 Hz,
(CH3CN) ppm. 29Si VACP/MAS NMR:
δ = –164.3 ppm.
C34H30N2O4Si (558.71): calcd. C 73.09, H 5.41, N 5.01; found C
73.01, H 5.39, N 4.76.
5cЈ:
1,1,1,5,5,5-Hexafluoro-4-(trimethylsilyloxy)pent-3-en-2-one
CCHC], 119.7 [q, 1J(13C,19F)
= 273.9 Hz, CF3], 124.3 [q,
(1.66 g, 5.92 mmol) was added in a single portion at 20 °C to a
stirred mixture of 2 (1.63 g, 4.94 mmol) and diethyl ether (50 mL),
and the reaction mixture was then stirred at this temperature for
3 d. All volatile components were removed in vacuo, diethyl ether
(15 mL) was added to the residue, and the resulting solution was
kept undisturbed at –20 °C for 3 d. The resulting precipitate was
isolated by filtration and dried in vacuo (0.01 mbar, 20 °C, 1 h) to
give 5cЈ in 78% yield (1.92 g, 3.83 mmol) as a red crystalline so-
1J(13C,19F) = 283.5 Hz, CF3], 146.9 [q, 2J(13C,19F) = 36.8 Hz,
CCF3], 125.6 (0.5 C), 126.8, 127.5 (2 C), 128.5, 128.7, 129.2, 129.3,
130.0, 131.4, 137.2 (2 C), 137.4, 137.6, 138.3 (0.5 C), 147.8
(SC6H4N, SiC6H5, C6H5CH3), 177.3 [C(N)CH3], 187.9 [C(O)CH3]
ppm. 19F NMR (CD2Cl2): δ = –81.6 (CF3), –75.3 (CF3) ppm. 29Si
NMR (CD2Cl2): δ = –125.3 ppm. 15N VACP/MAS NMR:[9] δ =
–205.3 ppm. 29Si VACP/MAS NMR:[9]
δ
=
–124.5 ppm.
C25.5H21F6NO3SSi (563.59): calcd. C 54.34, H 3.76, N 2.49, S 5.69;
4
lid.[10] 1H NMR (CD2Cl2): δ = 2.01 [d, J(1H,13C) = 0.4 Hz, 3 H,
found C 54.75, H 3.70, N 2.93, S 5.45.
CCH3], 2.50 (s, 3 H, CCH3), 5.46 [q, 4J(1H,13C) = 0.4 Hz, 1 H,
CCHC], 6.41 (s, 1 H, CCHC), 6.78–6.83, 6.83–6.86, 7.09–7.14,
7.17–7.25, 7.29–7.30, 7.42–7.46 (m, 9 H, OC6H4N, SiC6H5) ppm.
13C NMR (CD2Cl2): δ = 24.3 (CCH3), 24.8 (CCH3), 93.6 (CCHC),
5a·0.5CH3CN: 4-(Trimethylsilyloxy)pent-3-en-2-one
(700 mg,
4.06 mmol) was added in a single portion at 20 °C to a stirred mix-
ture of 2 (820 mg, 2.49 mmol) and acetonitrile (10 mL), and the
reaction mixture was stirred at this temperature for 2 h and then
heated until a clear solution was obtained, which was cooled slowly
to 20 °C and kept undisturbed at this temperature for 21 h and then
at –20 °C for a further 3 d. The resulting precipitate was isolated
by filtration, washed with n-pentane (10 mL), and dried in vacuo
(0.01 mbar, 20 °C, 2 h) to give 5a·0.5CH3CN in 76% yield (782 mg,
1.89 mmol) as a yellow crystalline solid. 1H NMR (CD2Cl2): δ =
1.91 (s, 3 H, CCH3), 1.95 (br. s, 3 H, CCH3), 1.96 (s, 1.5 H,
CH3CN), 2.13 (s, 3 H, CCH3), 2.35 (s, 3 H, CCH3), 5.19 (s, 1 H,
CCHC), 5.79 (s, 1 H, CCHC), 6.62–6.70, 6.96–7.01, 7.04–7.11,
7.12–7.16, 7.46–7.51 (m, 9 H, OC6H4N, SiC6H5) ppm. 13C NMR
(CD2Cl2): δ = 1.9 (CH3CN), 24.0 (CCH3), 24.7 (CCH3), 25.8
(CCH3), 26.0 (CCH3), 102.0 (CCHC), 102.4 (CCHC), 116.9
(CH3CN), 115.2, 117.2, 121.1, 126.1, 126.4 (2 C), 127.8, 133.1,
134.6 (2 C), 153.2, 155.8 (OC6H4N, SiC6H5), 167.8 [C(N)CH3],
176.5 [C(O)CH3], 189.7 [CO(CH3), O,O ligand], 192.5 [CO(CH3),
O,O ligand] ppm. 29Si NMR (CD2Cl2): δ = –165.1 ppm. 15N VACP/
MAS NMR: δ = –179.7, –177.7, –175.5, –174.8 ppm (four crystal-
lographically independent molecules), CH3CN not detected. 29Si
VACP/MAS NMR: δ = –168.1, –167.2, –166.1, –165.8 ppm (four
crystallographically independent molecules). C23H24.5N1.5O4Si
(414.04): calcd. C 66.72, H 5.96, N 5.07; found C 66.30, H 6.02, N
4.74.
1
104.3 (CCHC), 117.6 (q, J(13C,19F) = 283.8 Hz, 2 C, CF3], 115.3,
119.2, 120.9, 127.4 (2 C), 128.6, 128.8, 132.1, 134.1 (2 C), 142.2,
153.1 (OC6H4N, SiC6H5), 171.1 [C(N)CH3], 176.3 [C(O)CH3] ppm,
C(O)CF3 not detected. 19F NMR (CD2Cl2): δ = –76.9 ppm. 29Si
NMR (CD2Cl2): δ = –133.2 ppm. 15N VACP/MAS NMR: δ =
–187.3 ppm. 29Si VACP/MAS NMR:
δ
=
–134.4 ppm.
C22H17F6NO4Si (501.46): calcd. C 52.69, H 3.42, N 2.79; found C
53.02, H 3.40, N 2.97.
6a: 4-(Trimethylsilyloxy)pent-3-en-2-one (889 mg, 5.16 mmol) was
added in a single portion at 20 °C to a stirred mixture of 3 (1.11 g,
3.24 mmol) and acetonitrile (13 mL), and the reaction mixture was
then stirred at this temperature for 2 h. All volatile components
were removed in vacuo, acetonitrile (10 mL) was added to the resi-
due, and the mixture was heated until a clear solution was ob-
tained, which was cooled slowly to 20 °C and then kept undis-
turbed at this temperature for 21 h and then at –20 °C for a further
3 d. The resulting precipitate was isolated by filtration, washed with
n-pentane (8 mL), and dried in vacuo (0.01 mbar, 20 °C, 2 h) to
give 6a in 69% yield (910 mg, 2.24 mmol) as a dark-red crystalline
1
solid. H NMR (CD2Cl2): δ = 1.84 (s, 3 H, CCH3), 2.00 (s, 6 H,
CCH3), 2.28 (s, 3 H, CCH3), 2.53 (s, 3 H, NCH3), 5.11 (s, 1 H,
CCHC), 5.69 (s, 1 H, CCHC), 6.26–6.36, 6.91–6.95, 7.01–7.09,
7.39–7.44 (m, 9 H, NC6H4N, SiC6H5) ppm. 13C NMR (CD2Cl2): δ
= 23.7 (CCH3), 24.6 (CCH3), 25.9 (2 C, CCH3), 31.4 (NCH3), 101.9
(CCHC), 102.7 (CCHC), 107.6, 112.2, 120.7, 125.8, 126.2 (2 C),
127.7, 130.9, 134.8 (2 C), 149.7, 153.8 (NC6H4N, SiC6H5), 167.7
[C(N)CH3], 177.1 [C(O)CH3] ppm, C(O)CH3 (O,O ligand) not de-
tected. 29Si NMR (CD2Cl2): δ = –162.0 ppm. 15N VACP/MAS
NMR: δ = –284.6 (NCH3), –174.9 [C(N)CH3] ppm. 29Si VACP/
5b·CH3CN:
1,3-Diphenyl-3-(trimethylsilyloxy)prop-2-en-1-one
(494 mg, 1.67 mmol) was added in a single portion at 20 °C to a
stirred mixture of 2 (542 mg, 1.64 mmol) and acetonitrile (15 mL),
and the reaction mixture was then stirred at this temperature for
15 min. Acetonitrile (10 mL) was added, and the mixture was
heated until a clear solution was obtained, which was cooled slowly
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FULL PAPER
MAS NMR: δ = –163.4 ppm. C23H26N2O3Si (406.56): calcd. C
67.95, H 6.45, N 6.89; found C 67.84, H 6.24, N 6.86.
6b·CH3CN, and 6cЈ; graphite-monochromated Mo-Kα radiation, λ
= 0.71073 Å] or Bruker Nonius KAPPA APEX II (5a·0.53CH3CN
and 5b·CH3CN; Montel mirror, Mo-Kα radiation, λ = 0.71073 Å)}.
All structures were solved by direct methods (SHELXS-97[14]) and
refined by full-matrix least-squares methods on F2 for all unique
reflections (SHELXL-97[14]). SHELXLE was used as refinement
GUI.[15] For the CH hydrogen atoms, a riding model was employed.
CCDC-960664 (4cЈ·0.5C7H8), CCDC-960665 (5a·0.53CH3CN),
CCDC-960666 (5b·CH3CN), CCDC-960667 [5cЈ·(C2H5)2O],
CCDC-960668 (6a), CCDC-960669 (6b·CH3CN), and CCDC-
960670 (6cЈ) contain 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.
6b·CH3CN:
1,3-Diphenyl-3-(trimethylsilyloxy)prop-2-en-1-one
(739 mg, 2.49 mmol) was added in a single portion at 20 °C to a
mixture of 3 (564 mg, 1.64 mmol) and acetonitrile (8 mL), and the
reaction mixture was then stirred at this temperature for 1 h. All
volatile components were removed in vacuo, acetonitrile (13 mL)
was added to the residue, and the mixture was heated until a clear
solution was obtained, which was cooled slowly to 20 °C (forma-
tion of crystals) and then kept undisturbed at this temperature for
30 h. The resulting precipitate was isolated by filtration, washed
with n-pentane (8 mL), and dried in vacuo (0.01 mbar, 20 °C, 3 h)
to give 6b·CH3CN in 44% yield (412 mg, 721 μmol) as a dark-red
crystalline solid. 1H NMR (CD2Cl2): δ = 1.81 (s, 3 H, CCH3), 1.97
(s, 3 H, CH3CN), 2.37 (s, 3 H, CCH3), 2.47 (s, 3 H, NCH3), 5.13
(s, 1 H, CCHC), 7.00 (s, 1 H, CCHC), 6.90–6.97, 7.09–7.20, 7.48–
7.66, 7.96–8.02 (m, 19 H, NC6H4N, SiC6H5, CC6H5) ppm. 13C
NMR (CD2Cl2): δ = 2.1 (CH3CN), 23.5 (CCH3), 24.7 (CCH3), 31.6
(NCH3), 94.7 (CCHC), 102.9 (CCHC), 116.5 (CH3CN), 107.9,
110.6, 112.4, 120.6, 125.9, 126.3 (2 C), 127.5 (2 C), 127.8 (2 C),
128.4, 128.7, 129.1 (2 C), 131.4, 132.9, 133.2 (2 C), 135.1 (2 C),
135.8, 150.3, 153.3 (NC6H4N, SiC6H5, CC6H5), 167.7 [C(N)CH3],
177.6 [C(O)CH3], 186.1 (2 C, C(O)C6H5] ppm. 29Si NMR
(CD2Cl2): δ = –161.1 ppm. 15N VACP/MAS NMR: δ = –290.9
(NCH3), –175.3 [C(N)CH3], –126.4 (CH3CN) ppm. 29Si VACP/
MAS NMR: δ = –161.5 ppm. C35H33N3O3Si (571.75): calcd. C
73.53, H 5.82, N 7.35; found C 73.58, H 5.83, N 6.95.
Acknowledgments
We thank the referees of this paper for very helpful suggestions,
which have been included in this article.
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6cЈ:
1,1,1,5,5,5-Hexafluoro-4-(trimethylsilyloxy)pent-3-en-2-one
(1.99 g, 7.10 mmol) was added in a single portion at 20 °C to a
stirred mixture of 3 (1.62 g, 4.72 mmol) and acetonitrile (50 mL),
and the reaction mixture was then stirred at this temperature for
1 h. All volatile components were removed in vacuo, toluene
(15 mL) was added to the residue, and the resulting mixture was
heated until a clear solution was obtained, which was kept undis-
turbed at 20 °C for 16 h. The resulting precipitate was isolated by
filtration, washed with n-pentane (10 mL), and dried in vacuo
(0.01 mbar, 20 °C, 1 h) to give 6cЈ in 51% yield (1.25 g, 2.43 mmol)
[2] S. Metz, C. Burschka, R. Tacke, Organometallics 2009, 28,
2311–2317.
[3] For reviews dealing with higher-coordinate silicon(IV) com-
plexes, see: a) R. R. Holmes, Chem. Rev. 1996, 96, 927–950; b)
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1
as a colorless crystalline solid. H NMR (CD2Cl2): δ = 1.69 (s, 3
5
H, CCH3), 2.24 (s, 3 H, CCH3), 2.96 [q, J(1H,19F) = 2.3 Hz, 3 H,
NCH3], 5.80 (s, 1 H, CCHC), 5.91 (s, 1 H, CCHC), 6.80–6.84,
7.04–7.10, 7.22–7.27, 7.28–7.38, 7.71–7.75 (m, 9 H, NC6H4N,
SiC6H5) ppm. 13C NMR (CD2Cl2): δ = 24.2 (CCH3), 24.8 (CCH3),
35.0 [q, 4J(13C,19F) = 2.3 Hz, NCH3], 86.5 [q, 2J(13C,19F) =
28.6 Hz, CCF3], 101.1 [q, 3J(13C,19F) = 3.7 Hz, CCHC], 102.6
(CCHC), 120.0 [q, 1J(13C,19F)
= 273.6 Hz, CF3], 125.1 [q,
1J(13C,19F) = 297.7 Hz, CF3], 146.8 [q, 2J(13C,19F) = 35.2 Hz,
CCF3], 124.5, 125.1, 125.9, 127.4 (2 C), 128.9, 129.7, 137.1 (2 C),
138.5, 141.1, 143.3 (NC6H4N, SiC6H5), 176.9 [C(N)CH3], 187.3
[C(O)CH3] ppm. 19F NMR (CD2Cl2): δ = –77.3 (CF3), –75.1 (CF3)
ppm. 29Si NMR (CD2Cl2): δ = –124.2 ppm. 15N VACP/MAS
NMR: δ = –321.8 (NCH3), –203.4 [C(N)CH3] ppm. 29Si VACP/
MAS NMR: δ = –127.7 ppm. C23H20F6N2O3Si (514.50): calcd. C
53.69, H 3.92, N 5.44; found C 53.80, H 3.78, N 5.44.
7: This compound was synthesized according to ref.[11]
8: This compound was synthesized according to ref.[12]
9: This compound was synthesized according to ref.[13]
Crystal Structure Analyses: Suitable single crystals of 4cЈ·0.5C7H8,
5a·0.53CH3CN, 5b·CH3CN, 5cЈ·(C2H5)2O, 6a, 6b·CH3CN, and 6cЈ
were mounted in inert oil (perfluoropolyalkyl ether, ABCR) on a
glass fiber and then transferred to the cold nitrogen gas stream
of the diffractometer {Stoe IPDS [4cЈ·0.5C7H8, 5cЈ·(C2H5)2O, 6a,
Eur. J. Inorg. Chem. 2014, 475–483
482
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
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[6]
When using CH3CN instead of Et2O as the solvent, the same
product was formed but could not be isolated as a crystalline
solid.
One of the two CF3 groups and the solvent molecule are disor-
dered.
The Berry distortions were analyzed by using the PLATON
program system; A. L. Speck, Acta Crystallogr., Sect. D 2009,
65, 148–155.
As the structures of the two crystallographically independent
molecules are very similar, only one resonance signal was ob-
served.
[7]
[8]
[9]
[10]
Compound 5cЈ crystallizes from diethyl ether as the solvate
5cЈ·(C2H5)2O; however, upon drying the product in vacuo, the
solvent is completely removed.
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38, 1413–1416.
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Received: September 12, 2013
Published Online: December 18, 2013
Eur. J. Inorg. Chem. 2014, 475–483
483
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim