Synthesis and structure of cyclic trinuclear zinc disiloxides

Article abstract of DOI:10.1002/ejic.200600957

The synthesis and structure of the new disilane-1,2-diol [(Me ₃Si)₂SiOH]₂ (2b) and the trinuclear zinc disiloxides of the formula [Me2Si{(Me₃Si)₂SiO} ₂]₂Zn₃Me₂ (3a), [{(Me ₃Si)₂Si-O)₂]₂Zn₃Me ₂ (3b) and [E-{Me(Me₃Si)₃SiSiO} ₂]₂Zn₃Me₂ (3c) are reported. Compounds 3a-c were prepared by reactions of the corresponding silanedioles 2a-c with ZnMe₂. The results of an X-ray structure analysis of 3b reveal an almost perfectly planar spirocyclic Zn₃Q₄ core with a square-planar geometry of the inner Zn²⁺ ion, whereas in 3a,c the inner zinc ions are distorted tetrahedral. Upon treatment with B(C ₆F₅)₃, compounds 3b,c have been converted quantitatively into the complexes [{(Me₃Si)₂SiO} ₂]₂Zn₃(C₆F₅)₂ (4b) and [E-{Me(Me₃Si)₃SiSiO}₂] ₂Zn₃(C₆F₅)₂ (4c). Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200600957

SHORT COMMUNICATION
DOI: 10.1002/ejic.200600957
Synthesis and Structure of Cyclic Trinuclear Zinc Disiloxides
Clemens Krempner,*[a] Helmut Reinke,[a] and Katja Weichert[a]
Keywords: Oligosilanes / Zinc / Siloxides / Clusters
The synthesis and structure of the new disilane-1,2-diol
[(Me3Si)2SiOH]2 (2b) and the trinuclear zinc disiloxides of the
formula [Me2Si{(Me3Si)2SiO}2]2Zn3Me2 (3a), [{(Me3Si)2Si-
O}2]2Zn3Me2 (3b) and [E-{Me(Me3Si)3SiSiO}2]2Zn3Me2 (3c)
are reported. Compounds 3a–c were prepared by reactions
of the corresponding silanedioles 2a–c with ZnMe2. The re-
sults of an X-ray structure analysis of 3b reveal an almost
perfectly planar spirocyclic Zn3O4 core with a square-planar
geometry of the inner Zn2+ ion, whereas in 3a,c the inner zinc
ions are distorted tetrahedral. Upon treatment with B(C6F5)3,
compounds 3b,c have been converted quantitatively into the
complexes [{(Me3Si)2SiO}2]2Zn3(C6F5)2 (4b) and [E-
{Me(Me3Si)3SiSiO}2]2Zn3(C6F5)2 (4c).
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Introduction
Results and Discussion
There has been a considerable interest in recent years in
the chemistry and structures of zinc siloxides as the steric
hindrance of the ligand (R3SiO–) in such compounds can
lead to novel structural features and unusual reactivity.[1]
For example, some structurally well-defined zinc com-
pounds have been found application as soluble precursors
for zinc oxides and silicates.[2] Significant synthetic and
structural studies of a variety of mainly monodentate zinc
siloxides are reported from the Driess group. They could
demonstrate that the degree of aggregation of the central
(ZnO)n core decreases as the bulkiness of the attached silox-
ide ligand increases.[3] Bidentate cyclic zinc siloxides, how-
ever, are rare and the only example has been reported from
the reaction of ZnMe2 with Ph2Si(OH)2, which under self-
condensation of the silanol affords a remarkable polycyclic
hexanuclear zinc complex with two Zn3O4 cores.[4]
A rather straightforward strategy for the design of vicinal
silanediols with an oligosilane backbone involves the use of
phenyl-substituted metal silanides in salt metathesis reac-
tions. In analogy to the synthesis of the trisilane-1,3-diol
2a previously reported,[5] treatment of Ph(Me3Si)2Si-K with
BrCH2CH2Br provides easy access to the diphenyl oligosil-
ane 1b in high yields.[6] This compound was treated with
two equivalents of trifluoromethanesulfonic acid (TfOH)
and subsequently hydrolyzed to give almost quantitatively
the silanediol 2b as a colorless solid (Scheme 1). The com-
pound slowly decomposes at room temperature within sev-
eral days and must be stored in a freezer at ca. –40 °C.
However, the structure of 2b was unambiguously estab-
lished by standard spectroscopic methods and elemental
analysis. The synthesis of the racemic disilane-1,2-diol 2c
has been reported elsewhere.[7]
We have a long-term interest in the synthesis and struc-
tural characterization of cyclic five- and six-membered
metal disiloxides, as these highly strained cycles might be
useful for the selective ring insertion of metal species, which
may form novel hetero- and homobimetallic complexes as
we have shown recently for a dinuclear titanium disiloxide
derived from a mononuclear cyclic species.[5] In this contri-
bution we describe the preparation of a new disilane-1,2-
diol and we report on the synthesis of polycyclic trinuclear
zinc disiloxides from reactions of ZnMe2 with various steri-
cally congested vicinal silanediols together with their solid-
state structures.
Scheme 1. Synthesis of 2b.
As reported recently, differently aggregated zinc silanol-
ates can be prepared by acid–base reactions of silanols
R3SiOH (R = Me, Et, iPr, Ph) with ZnR2 (R = Me, Et).
[a] Institut für Chemie der Universität Rostock,
Albert-Einstein-Str. 3a, 18059 Rostock, Germany
Eur. J. Inorg. Chem. 2007, 1067–1071
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C. Krempner, H. Reinke, K. Weichert
SHORT COMMUNICATION
Employing ZnMe2 as the reagent the trinuclear zinc com-
plexes 3a–c have been synthesized in good yields as outlined
in Scheme 2. The NMR and MS data and the results of
elemental analysis have confirmed the proposed structures
of 3a–c. The NMR (1H, 13C, 19Si) spectra of all complexes
are rather straightforward and show roughly the same fea-
tures as observed for the corresponding free ligands 2a–c.
1
For example, the H and 13C NMR spectra of 3a exhibit
only one signal for the SiMe3 and SiMe2 groups, respec-
tively, and also the 29Si NMR spectra showed only one sig-
nal for the SiMe3 silicon atoms.
Figure 1. Molecular structure of 3a in the crystal. The thermal el-
lipsoids correspond to 30% probability (hydrogen atoms are omit-
ted for clarity). Selected bond lengths [Å] and angles [°]: Zn1–C1
1.942(4), Zn3–C2 1.934(5), Zn2–O1 1.975(2), Zn2–O2 1.968(2),
Zn2–O3 1.959(2), Zn2–O4 1.973(2), Zn1–O1 1.952(2), Zn1–O2
1.954(2), Zn3–O3 1.953(2), Zn3–O4 1.959(2), Si2–O1 1.673(2), Si4–
O3 1.673(2), Si9–O2 1.678(2), Si11-O4 1.679(2), Si2–Si3 2.3597(14),
Si3–Si4 2.3775(14), O3–Zn2–O2 135.37(10), O3–Zn2–O4 85.50(9),
O2–Zn2–O4 112.70(9), O3–Zn2–O1 110.92(9), O2–Zn2–O1
84.63(9), O4–Zn2–O1 135.80(10), O1–Zn1–O2 85.64(9), O3–Zn3–
O4 86.03(9), C1–Zn1–O1 137.17(14), C2–Zn3–O3 140.12(19), Zn2–
O3–Si4–Si3 45.43(18), O3–Si4–Si3–Si2 14.59(12), Si4–Si3–Si2–O1
23.79(12), Si3–Si2–O1–Zn2 43.74(19), Si2–O1–Zn2–O3 21.8(2),
O1–Zn2–O3–Si4 34.34(19).
Scheme 2. Synthesis of 3a–c and reaction behavior toward
B(C6F5)3.
In addition, the solid-state structures of 3a–c have been
determined by X-ray crystallography; suitable single crys-
tals were grown from pentane solutions at room tempera-
ture. The molecular structures along with selected bond
lengths and bond angles are shown in Figure 1, 2, 3, and 4.
¯
Compounds 3a–c crystallize in the triclinic space group P1.
All structures consist of fused polycyclic ring systems with
central trinuclear Zn3O4 cores, which are coordinated in a
chelate fashion by two diolate ligands, respectively. The co-
ordination of the ligand to the inner zinc ion in 3a results
in the formation of a six-membered ring system with a dis-
torted chair conformation. In 3b and 3c, however, five-
membered rings are formed, which are either strongly
twisted [3b; dihedral angle O1–Si2–Si3–O2 32.05(6)°] or al-
most planar [3c; dihedral angle O1–Si3–Si4–O2 2.70(10)°].
The outer zinc atoms of 3a and 3c are three-coordinate with
trigonal-planar ligand environments, while the inner Zn2+
ions are four-coordinate with distorted tetrahedral geome-
tries. Overall, the observed distorted geometries of the
Zn3O4 cores are in good agreement with those of the mono-
Figure 2. Molecular structure of 3b in the crystal. The thermal el-
lipsoids correspond to 30% probability (hydrogen atoms are omit-
ted for clarity). Selected bond lengths [Å] and angles [°]: Zn2–C13
1.9223(16), Zn1–O1 1.9721(9), Zn1–O2 1.9831(10), Zn2–O2
1.9438(10), Zn2–O1 1.9403(10), Si2–O1 1.6744(11), Si3–O2
1.6763(10), Si2–Si3 2.3832(5), O1–Zn1–O2 96.88(4), O1–Zn1–O1A
180.0, O1–Zn1–O2A 83.12(4), O2–Zn2–O1A 84.99(4), O1A–Zn2–
C13 137.63(8).
The most remarkable feature of the zinc siloxide 3b, how-
dentate zinc siloxides [(iPr3SiO)4Zn3Me2] (5),[2a] [(Ph3SiO)4- ever, is the unusual square-planar coordination geometry of
Zn3Me2] (6)[4] and [(OSiPh2OSiPh2O)(OSiPh2)OZn2Me2· the inner Zn2+ ion. To the best of our knowledge, this is
THF]2 (7)[4] (see Table 1).
the first completely planar structure with a spirocyclic
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Eur. J. Inorg. Chem. 2007, 1067–1071

Synthesis and Structure of Cyclic Trinuclear Zinc Disiloxides
SHORT COMMUNICATION
Table 1. Selected average bond lengths [Å] and angles [°] for trinu-
clear zinc disiloxides.
Compound
3a
3b
3c
5[a]
6[b]
7[c]
Zn–C
Si–O
Zninner–O
Znouter–O
O–Zninner–O
1.94
1.68
1.97
1.95
85/86
86/111
113/135 180
86
177
1.92 1.93
1.68 1.67
1.98 1.97
1.94 1.97
1.95
1.65
1.97
1.98
87/87
1.92
1.64
1.95
1.96/2.01 2.02
84/86
1.95
1.61
1.96
83
97
87/87
88/88
114/104
133/138
84
101/102 117/120 112/120
148/151 120/131 124/133
O–Znouter–O
Zn–Zn–Zn
85
87
86
166
84
159
180
177
176
[a] [(iPr3SiO)4Zn3Me2]. [b] [(Ph3SiO)4Zn3Me2]. [c] [(OSiPh2OSi-
Ph2O)(OSiPh2)OZn3Me2·THF]2.
Figure 3. View along the Si2–Si3 axis of 3b. Selected dihedral
angles (all methyl groups are omitted for clarity): Si6–Si3–Si2–Si5
42.01(3)°, O1–Si2–Si3–O2 32.05(6), Si1–Si2–Si3–Si4 44.18(3), Si1–
Si2–Si3–Si6 86.92(3), Si5–Si2–Si3–Si4 173.12(2).
rocyclic ZnO2ZnO2Zn core. This is not evident for 3a, be-
cause the SiMe2 spacer group, which reduces steric repul-
sions within the molecule, separates the vicinal trimethyl-
silyl groups. Consequently the bulky trimethylsilyl groups
can adopt an eclipsed conformation, which enables the in-
ner zinc ion to be coordinated in the energetically preferred
tetrahedral geometry.
For comparison, a summary of selected average distances
and angles together with those of the complexes recently
reported by Driess et al. is given in Table 1. As expected,
the Zn–O distances and O–Zn–O angles of the inner zinc
ions and also the Zn–C distances in all these complexes are
rather similar to each other. It is worthy to note, however,
that the Si–O distances in 3a–c are markedly longer and the
Zn–O distances for the outer zinc ions are shorter than
those of the closely related complexes 5–7. The longer Si–
O distances can be attributed to the specific electronic situa-
tion in 3a–c, in which the central silicon atoms possess elec-
tropositive silyl groups. These electron-donating groups
clearly diminish the capability of silicon to act as strong π
acceptor for oxygen, which gives rise to stronger electro-
static oxygen–zinc interactions and consequently to shorter
Zn–O distances as compared to 5–7.
Figure 4. Molecular structure of 3c in the crystal. The thermal el-
lipsoids correspond to 30% probability (hydrogen atoms are omit-
ted for clarity). Selected bond lengths [Å] and angles [°]: Zn2–C2
1.934(3), Zn3–C1 1.933(3), Zn1–O1 1.9665(17), Zn1–O2
1.9650(16), Zn1–O3 1.9677(16), Zn1–O4 1.9650(16), Zn2–O1
1.9687(17), Zn2–O3 1.9588(16), Zn3–O2 1.9644(16), Zn3–O4
1.9664(16), Si3–O1 1.6672(17), Si4–O2 1.6650(17), Si13–O3
Furthermore, we have investigated the reactivity of the
highly strained trinuclear zinc complexes 3b,c towards the
Lewis acid B(C6F5)3 that is known to abstract alkyl groups
1.6653(17), Si14–O4 1.6685(17), Si3–Si4 2.4229(9), Si13–Si14 from the metal center to form cationic metal species. The
2.4003(9), Si2–Si3 2.3891(10), O2–Zn1–O4 86.64(7), O2–Zn1–O1
101.54(7), O4–Zn1–O1 151.34(8), O2–Zn1–O3 147.62(7), O4–Zn1–
O3 100.93(7), O1–Zn1–O3 86.84(7), O3–Zn2–O1 87.02(7), O2–
Zn3–O4 86.62(7), C2–Zn2–O3 135.32(12), C2–Zn2–O1 137.66(12),
reactions were performed at room temperature in a J-Young
NMR tubes using [D6]benzene as solvent, and the course
1
of the reaction was monitored by H NMR spectroscopy.
The complexes 3b,c reacted cleanly with B(C6F5)3 (molar
ratio 1:1) within minutes, resulting in the formation of
[{(Me3Si)2SiO}2]2Zn3(C6F5)2 (4b) and [E-{Me(Me3Si)3-
C1–Zn3–O4 134.97(11), O1–Si3–Si4–O2 2.70(10), O3–Si13–Si14–
O4 10.53(10).
Zn3X4 core (X = S, O, N, P). Apart from three planar mo- SiSiO}2]2Zn3(C6F5)2 (4c), the quantitative products of a ra-
nonuclear zinc complexes with bidentate phenolate type li- pid C6F5 group transfer, as evidenced by multinuclear
gands,[8] only in porphyrin complexes the zinc ion has an NMR spectroscopic data. The compounds 4b,c could be
almost perfect square-planar coordination environment. A isolated in a larger scale and the spectroscopic data ob-
view along the Si2–Si3 axis in 3b (Figure 3) clearly reveals tained were identical to those from the NMR experiments
this arrangement to be mainly enforced by the steric repul- (Scheme 2). Solutions of 4b,c in C6D6 proved to be fairly
sion of the adjacent trimethylsilyl groups. In fact, the steric stable over a prolonged period of time, and even at higher
interactions of the trimethylsilyl groups can be significantly temperature no substantial decomposition occurred. Sim-
minimized by adopting a staggered conformation along the ilar C6F5 transfer reactions have been observed for the reac-
Si2–Si3 axis, which results in the formation of a planar spi- tion of ZnMe2.[9] The fact that the C6F5 groups have re-
Eur. J. Inorg. Chem. 2007, 1067–1071
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1069

C. Krempner, H. Reinke, K. Weichert
SHORT COMMUNICATION
7.2 mmol) in n-pentane (20 mL) at –78 °C. After stirring for 2 h at
room temp., the solvent was removed under vacuum. Crystalli-
zation of a concentrated n-pentane solution in a freezer at –40 °C
afforded the title compound as colorless crystals. Yield 1.75 g
placed both methyl groups rapidly is somewhat surprising;
however, it indicates an increased electrophilicity of the zinc
centers caused by the electron-withdrawing disiloxide li-
gands.
1
(65%). M.p. 115–117 °C. H NMR (C6D6, 250 MHz): δ = 0.43 [s,
Si(CH3)2, 12 H], 0.34 [s, Si(CH3)3, 72 H], –0.04 (s, ZnCH3, 6 H)
ppm. 13C NMR (C6D6, 75.5 MHz): δ = 1.2 [Si(CH3)3], –0.4
[Si(CH3)2], –10.8 (ZnCH3) ppm. 29Si NMR (C6D6, 59.6 MHz): δ =
14.8 (SiOZn), –16.1 [Si(CH3)3], –37.1 [Si(CH3)2] ppm. C30H90O4-
Si14Zn3 (1104.40): calcd. C 32.63, H 8.21; found C 32.47, H 8.24.
Experimental Section
General Remarks: All manipulations of air- and/or moisture-sensi-
tive compounds were carried out under argon using standard
Schlenk and Glove Box techniques. THF, n-heptane and n-pentane
were distilled under argon from alkali metals prior to use. CH2Cl2
was distilled from CaH2 and stored over molecular sieves. [D6]Ben-
zene was dried with activated molecular sieves and stored in the
glove box. B(C6F5)3 was prepared as described previously.[10]
NMR: Bruker AC 250, Bruker ARX 300. IR: Nicolet 205 FT-IR.
MS: Intectra AMD 402, chemical ionization with isobutane as the
reactant gas.
[{(Me3Si)2SiO}2]2Zn3Me2 (3b): A heptane solution of 2b (0.5 g,
1.31 mmol) was added to a vigorously stirred solution of ZnMe2
(2 , 0.8 mL, 1.6 mmol) in n-pentane (20 mL) at –78 °C. After stir-
ring for 2 h at room temp., the solvent was removed under vacuum.
Crystallization of a concentrated n-pentane solution in a freezer at
–40 °C afforded the title compound as colorless crystals. Yield
0.41 g (63%). M.p. 169–171 °C. 1H NMR (C6D6, 250 MHz): δ =
0.30 [s, Si(CH3)3, 72 H], –0.13 (s, ZnCH3, 6 H) ppm. 13C NMR
(C6D6, 75.5 MHz): δ = 0.1 [Si(CH3)3], –15.1 (ZnCH3) ppm. 29Si
NMR (C6D6, 59.6 MHz): δ = 1.2 (SiOZn), –16.4 [Si(CH3)3] ppm.
C26H78O4Si12Zn3 (988.09): calcd. C 31.60, H 7.96; found C 31.42,
H 7.84.
2,3-Dihydroxy-1,1,1,4,4,4-hexamethyl-2,3-bis(trimethylsilyl)tetra-
silane (2b): Freshly distilled TfOH (0.97 mL, 0.011 mol) was added
at –40 °C to a stirred solution of 1b (2.51 g, 0.005 mol) in CH2Cl2
(25 mL) and the mixture was warmed to room temp. within 2 h.
After changing the solvent from CH2Cl2 to diethyl ether, an aque-
ous solution of NH4COONH2 (10 mL, 1 ) was added dropwise
and stirring was continued for 30 min. The organic phase was sepa-
rated, dried with MgSO4, and the solvent was evaporated. Drying
under high vacuum afforded 1.76 g (92%) of the title compound,
[E-{Me(Me3Si)3SiSiO}2]2Zn3Me2 (3c): A heptane solution of 2c
(0.5 g, 0.81 mmol) was added to a vigorously stirred solution of
ZnMe2 (2 , 0.6 mL, 1.2 mmol) in n-heptane (15 mL) at –78 °C.
After warming to room temp., the suspension was stirred overnight
and refluxed until the colorless precipitate fully dissolved. Crystalli-
zation of the solution at room temp. afforded the title compound as
1
which was kept in a freezer. H NMR (C6D6, 250 MHz): δ = 0.72
(br. s, OH, 2 H), 0.29 [s, Si(CH3)3, 36 H] ppm. 13C NMR (C6D6,
62.9 MHz): δ = 0.1 [Si(CH3)3] ppm. 29Si-INEPT (C6D6, 59.6 MHz):
δ = 8.1 (SiOH), –15.0 [Si(CH3)3] ppm. MS (70 eV): m/z (%) = 383
(8) [M+], 279 (8) [M+ – 2Me – SiMe3], 205 (20) [M+ – Me –
2SiMe3 – OH], 131 (42) [M+ – Me – 3SiMe3 – OH]. C12H38O2Si6
(382.94): calcd. C 37.64, H 10.00; found C 37.49, H 9.98. IR (Nu-
1
colorless crystals. Yield 0.45 g (75%). M.p. 161–164 °C. H NMR
(C6D6, 250 MHz): δ = 0.94 (s, SiCH3, 12 H), 0.41 [s, Si(CH3)3, 108
H], 0.04 (s, ZnCH3, 6 H) ppm. 13C NMR (C6D6, 75.5 MHz): δ =
11.0 (SiCH3), 4.6 [Si(CH3)3], –10.3 (ZnCH3) ppm. 29Si NMR
(C6D6, 59.6 MHz): δ = 15.8 (SiOZn), –10.0 [Si(CH3)3], –127.1
(SiSi4) ppm. MS (70eV): m/z (%) = 1438 (2) [M+ – Me], 1207 (22)
[M+ – Si(SiMe3)3], 1110 (8) [M+ – Si(SiMe3)3 – 2Me – Zn], 247 (35)
jol): ν
= 3394.4 cm–1 (assoc.), 3641.6 cm–1 (non-assoc.).
˜
OH
[Me2Si{(Me3Si)2SiO}2]2Zn3Me2 (3a): Solid 2a (2.0 g, 4.5 mmol) [Si(SiMe3)3]. C42H126O4Si20Zn3 (1453.33): calcd. C 34.71, H 8.74;
was added to a vigorously stirred solution of ZnMe2 (2 , 3.6 mL, found C 34.51, H 8.74.
Table 2. Crystal data collection, and refinement details for crystal structures.[a]
Compound
3a
3b
3c
Formula
C30H90O4Si14Zn3
1104.39
C26H78O4Si12Zn3
988.07
C42H126O4Si20Zn3·C6H14
1539.51
Molecular weight
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
1.00ϫ0.37ϫ0.22
triclinic
0.67ϫ0.35ϫ0.22
triclinic
0.62ϫ0.62ϫ0.36
triclinic
¯
¯
¯
P1
P1
P1
13.9735(4)
14.1182(3)
18.5569(5)
81.7090(10)
68.8770(10)
65.2840(10)
3102.01(14)
2
9.8213(6)
11.5149(7)
13.5301(13)
102.830(4)
97.107(4)
111.836(3)
1348.43(17)
1
14.2317(6)
17.3635(7)
21.2325(8)
68.0030(10)
78.540(2)
71.779(2)
4601.1(3)
2
α [°]
β [°]
γ [°]
V [Å]3
Z
ρ [g/cm3]
1.182
1.448
1.217
1.615
1.111
1.067
µ [mm–1]
2Θ limit [°]
Measured reflections
Independent reflections
2.97–25.00
56017
10852
[R(int) = 0.0696]
10852/0/491
0.0661/0.1812
1.99–27.50
53729
6125
[R(int) = 0.0304]
6125/0/218
0.0210/0.0558
2.21–25.00
82788
15934
[R(int) = 0.0246]
15934/0/678
0.0367/0.1030
Data/restraints/parameter
Final R1/wR2
[b]
[a] All data sets were collected with a Bruker X8Apex diffractometer system with Mo-Kα radiation [λ = 0.71073 Å at 173(2) K]. [b] The
value of R1 is based on selected data with F Ͼ4σ(F); the value of wR2 is based on all data.
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Eur. J. Inorg. Chem. 2007, 1067–1071

Synthesis and Structure of Cyclic Trinuclear Zinc Disiloxides
SHORT COMMUNICATION
Reaction of 3b,c with B(C6F5)3 in C6D6: An NMR tube (equipped
with J. Young valve) was charged in the glove box with 3b or 3c
and B(C6F5)3 (molar ratio 1:1) and dissolved in C6D6 (0.5 mL).
The progress of the reaction was monitored by 1H NMR spec-
troscopy and complete conversion of the starting materials into 4b
and 4c and a mixture of the boranes MeB(C6F5)2 (δ = 1.35 ppm),
Me2BC6F5 (δ = 0.98 ppm) and BMe3 (δ = 0.74 ppm) was observed
within 2 h at room temperature, according to the 1H , 29Si , 11B
and 19F NMR spectra.
mentary 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.
[1] a) F. Schindler, H. Schmidbaur, U. Krüger, Angew. Chem. 1965,
77, 865; Angew. Chem. Int. Ed. Engl. 1965, 4, 876; b) F.
Schindler, H. Schmidbaur, Angew. Chem. 1967, 79, 697–708;
Angew. Chem. Int. Ed. Engl. 1967, 6, 683–694; c) G. Ananthar-
aman, H. W. Roesky, J. Magull, Angew. Chem. 2002, 114, 1525;
Angew. Chem. Int. Ed. 2002, 41, 1226–1229.
Isolation of 4b,c: A stirred mixture of B(C6F5)3 and 3b or 3c (molar
ratio 1:1) was dissolved in n-pentane at ca. –20 °C and stirring was
continued for 2 h at room temperature. Crystallizations of concen-
trated solutions in a freezer afforded colorless crystals of the title
compounds.
[2] a) K. Su, T. D. Tilley, M. J. Sailor, J. Am. Chem. Soc. 1996,
118, 3459–3468; b) A. Fina, H. C. L. Abbenhuis, D. Tabuani,
A. Frache, G. Camino, Polym. Degrad. Stab. 2006, 91, 1064–
1070; c) J. Hambrock, M. Rabe, K. Merz, A. Birkner, A.
Wohlfart, R. A. Fischer, M. Driess, J. Mater. Chem. 2003, 13,
1731–1736.
[{(Me3Si)2SiO}2]2Zn3(C6F5)2 (4b): Compound 3b (0.15 g,
0.15 mmol), B(C6F5)3 (0.08 g, 0.15 mmol) and n-pentane (10 mL).
Yield 0.1 g (67%). 1H NMR (C6D6, 250 MHz): δ = 0.24 [s, Si-
(CH3)3, 72 H] ppm. 13C NMR (C6D6, 75.6 MHz): δ = –0.1 [Si-
(CH3)3], 135.4–150.6 (C6F5) ppm. 29Si NMR (C6D6, 59.6 MHz): δ
= 7.9 (SiO), –16.0 [Si(CH3)3] ppm. 19F NMR (C6D6, 235.4 MHz):
δ = –169.5, –140.2, –116.2 (o-, p-, m-F, C6F5) ppm. C36H72F10O4-
Si12Zn3 (1292.11): calcd. C 33.46, H 5.62; found C 33.09, H 5.44.
[3] a) M. Driess, K. Merz, S. Rell, Eur. J. Inorg. Chem. 2000, 2517–
2522; K. Merz, S. Block, R. Schoenen, M. Driess, Dalton
Trans. 2003, 3365–3369.
[4] K. Merz, H. M. Hu, S. Rell, M. Driess, J. Inorg. Chem. 2003,
51–53.
[5] C. Krempner, M. Köckerling, H. Reinke, K. Weichert, Inorg.
Chem. 2006, 45, 3203–3211.
[6] C. Krempner, U. Jäger-Fiedler, K. Mamat, A. Spannenberg, K.
Weichert, New J. Chem. 2005, 29, 1581–1584.
[7] D. Hoffmann, H. Reinke, C. Krempner, J. Organomet. Chem.
2002, 662, 1–8.
[8] a) H. N. Hou, Acta Crystallogr., Sect. E 2005, 61, 1197–1198;
b) Z. Y. Xiong, L. J. Liu, Acta Crystallogr., Sect. E 2005, 61,
863–864; c) Q. Chen, Acta Crystallogr., Sect. E 2006, 62, 56–
57.
[9] D. A. Walker, T. J. Woodmann, D. L. Hughes, M. Bochmann,
Organometallics 2001, 20, 3772–3776.
[10] A. N. Chernega, A. J. Graham, M. L. H. Green, J. Haggitt, J.
Lloyd, C. P. Mehnert, N. Metzler, J. Souter, J. Chem. Soc., Dal-
ton Trans. 1997, 13, 2293–2303.
[E-{Me(Me3Si)3SiSiO}2]2Zn3(C6F5)2 (4c): Compound 3c (0.15 g,
0.1 mmol), B(C6F5)3 (0.05 g, 0.1 mmol) and n-pentane (10 mL).
Yield 0.09 g (61%). 1H NMR (C6D6, 250 MHz): δ = 1.00 (s, SiCH3,
12 H), 0.31 [s, Si(CH3)3, 72 H] ppm. 13C NMR (C6D6, 75.6 MHz): δ
= 4.5 [Si(CH3)3], 10.9 (SiCH3), 136.1–151.2 (C6F5) ppm. 29Si NMR
(C6D6, 59.6 MHz): δ = 21.0 (SiO), –9.9 [Si(CH3)3], –125.4 (SiSi4)
ppm. C52H120F10O4Si20Zn3 (1757.35): calcd. C 35.54, H 6.88; found
C 35.18, H 6.79.
Crystal data collection see Table 2 for 3a, 3b and 3c are deposited
in the Cambridge Crystallographic Data Centre. CCDC-622651
(for 3a), -622650 (for 3b) and -622649 (for 3c) contain the supple-
Received: October 12, 2006
Published Online: February 2, 2007
Eur. J. Inorg. Chem. 2007, 1067–1071
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1071