1-Oxa-3-aza-2,4-disilacyclobutanes - Synthesis, X-ray structures, and reactivity

Article abstract of DOI:10.1002/1099-0682(200107)2001:7<1889::AID-EJIC1889>3.0.CO;2-6

Lithium aminodi(tert-butyl)silanolate reacts with F₃SiR to give the aminosiloxane (Me₃C)₂SiNH₂-O-SiF₂R [1; R = 2,4,6-(tBu)₃C₆H₂]. In the reaction of 1 with BuLi a four-membered (Si-O-Si-NH) ring system 2 is formed [-(Me₃C)₂Si-O-SiFR-NH-]. The amino-1,3-disiloxane RSiF₂-NH-Si-(CMe₃)₂-O-SiF₂R (3) is obtained from dilithiated amino(ditert-butyl)silanol and F₃SiR. Compound 1 reacts with BuLi with formation of a dimeric lithium derivative through the Li-N bond (4). In 4 the transannular Si···Si distance was found to be 237.2 pm, which is the shortest distance so far found between two silicon atoms contained in four-membered rings. Compound 4 reacts with Me₃SiOSO₂CF₃ with substitution of the lithium by the Me₃Si group to give 5.

Full text of DOI:10.1002/1099-0682(200107)2001:7<1889::AID-EJIC1889>3.0.CO;2-6

FULL PAPER
1-Oxa-3-aza-2,4-disilacyclobutanes ؊ Synthesis, X-ray Structures,
and Reactivity
Uwe Klingebiel,*[a] M. Noltemeyer[a]
Keywords: Silicon / Structure elucidation / Silanes / Small ring systems
Lithium aminodi(tert-butyl)silanolate reacts with F3SiR to
give the aminosiloxane (Me3C)2SiNH2−O−SiF2R [1; R = 2,4,6- Li−N bond (4). In 4 the transannular Si···Si distance was
(tBu)3C6H2]. In the reaction of 1 with BuLi a four-membered
found to be 237.2 pm, which is the shortest distance so far
(Si−O−Si−NH) ring system is formed [−(Me3C)2Si− found between two silicon atoms contained in four-mem-
with formation of a dimeric lithium derivative through the
2
O−SiFR−NH−]. The amino-1,3-disiloxane RSiF2−NH−Si-
(CMe3)2−O−SiF2R (3) is obtained from dilithiated amino(di-
tert-butyl)silanol and F3SiR. Compound 1 reacts with BuLi
bered rings. Compound 4 reacts with Me3SiOSO2CF3 with
substitution of the lithium by the Me3Si group to give 5.
Introduction
reactions with other halosilanes silylamino-1,3-disiloxanes
are obtained.
In silicon chemistry it is possible to stabilize compounds
with two or three OH or NH2 groups bonded to one silicon
atom, in contrast to carbon chemistry. The first silanediols
and -diamines were described by Sommer and Tyler in the
fifties.[1] Silanetriols and -triamines followed about thirty
years later.[2Ϫ4] We succeeded in preparing stable halosilan-
ols,[5] (e.g. chlorosilanols) from the reaction of silanediols
with PCl5, accompanied by formation of HCl and POCl3.
The reaction of di-tert-butyl-dichlorosilane with ammonia
proceeds with complete cleavage of hydrogen chloride to
afford the amino-di-tert-butylsilanol, the only aminosilanol
known so far,[2,6] which is stable towards self-reaction
[Equation (1)].
In attempting to obtain cyclic products by salt elimina-
tion from isomeric lithium compounds we isolated eight-
membered (SiϪOϪSiϪN) rings [Equation (2)].[9,10] Lithium
derivatives of type I are found to be very stable; they can
be distilled without decomposition.[11] However, they are
direct precursors of four-membered (SiϪOϪSiϪN) rings
when catalytic amounts (1Ϫ5%) of fluorosilanes are added
to a solution of the lithium compounds.[8,12]
In this paper we describe the preparation of 1-[amino-
1,1-di(tert-butyl)]-3-[2,4,6-tri(tert-butyl)phenyl]-3,3-di-
fluoro-1,3-disiloxane, its cyclisation to the first
(SiϪNHϪSiϪO) four-membered ring system, and the
formation of its lithium derivative.
Results and Discussions
In preparative ring chemistry bulky groups lead to the
formation of small ring compounds. In order to prepare a
fluoro-functionalized Si(F)ϪOϪSiϪN(H) four-membered
ring system we used the bulky Si(CMe3)2 and F2SiC6H2-
(CMe3)3 units. The lithiated aminodi(tert-butyl)silanol[6] re-
acts with 2,4,6-tri(tert-butyl)phenyltrifluorosilane to yield
the aminosiloxane 1 [Equation (3)], which is stable against
HF or NH3 condensation.
Our attempts to isolate the lithium derivative of 1 in the
reaction of 1 and BuLi were unsuccessful, LiF elimination
occurred and the 1-aza-3-oxa-2,4-disilacyclobutane 2 was
obtained [Equation (4)].
The kinetic stabilization of the aminosilanol led to the
stepwise synthesis of numerous acyclic and cyclic organosil-
icon compounds.[7] After lithiation of the aminosilanol,[6]
treatment with a halosilane always results in attachment of
the new organosilicon group to the oxygen atom; aminosi-
loxanes are formed [Equation (2)]. Lithiation of these ami-
nosiloxanes normally leads again to the bonding of lithium
to the oxygen atom. In this case aminosilanolates of type I
are formed. This means that in the lithiation reaction the
silyl substituent on the oxygen atom is displaced by the
Lewis acidic lithium, so that an O Ǟ N silyl group migra-
tion is observed.[8] This rearrangement can be prevented by
bulky groups [Equation (2)]. Siloxaneamides of type II are
then formed. Therefore the success of the substitution of
the silyl groups determines which isomer is obtained.[8] In
Crystal Structure of 2
¯
Colorless crystals of 2 with space group P1 were obtained
from a saturated solution of n-hexane. The atoms N(1),
Si(1), O(1) and Si(2) of the molecule form a planar four-
membered ring, but there are some irregularities as follows.
At the oxygen and the nitrogen atoms there is a slight open-
[a]
Institut für Anorganische Chemie der Georg-August-
Universität Göttingen,
Tammannstraße 4, 37077 Göttingen, Germany
E-mail: uklinge@gwdg.de
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ1948/01/0707Ϫ1889 $ 17.50ϩ.50/0
1889

U. Klingebiel, M. Noltemeyer
FULL PAPER
ing of the Si(1)ϪO(1)ϪSi(2) angle (93.42°) and the
Si(1)ϪN(1)ϪSi(2) angle (94.03°), which is accompanied by
a contraction of the angles at the other ring atoms
[N(1)ϪSi(1)ϪO(1) ϭ 87.15°; N(1)ϪSi(2)ϪO(1) ϭ 85.4°].
The Si(1)ϪO(1) (167.2 pm), and the Si(2)ϪO(1) (170.2 pm)
bond lengths are lengthened. The Si(1)ϪN(1) (166.6 pm)
and Si(2)ϪN(1) (169.1 pm) bonds are short, even shorter
than the SiϪO bonds. In order to see if there is any O/NH
split occupancy of O(1) re-refinements of O/NH occupan-
cies were carried out on both sites. However, strong correla-
tion with ADPS leads to unstable refinement. Also, no hy-
drogen atoms could be located in the difference maps and
riding models had to be used throughout. The Si···Si non-
bonding distance in the ring is 245.6 pm, the corresponding
N···O distance is 230.1 pm. These short distances illustrate
that the ring atoms in a four-membered ring as strained as
this one are forced to approach each other to an extraordin-
ary extent. The C(1) atom of the aryl group is found to
have no planar environment: the sum of the angles at C(1)
amounts to 355.7°. Figure 1 shows the structure of com-
pound 2.
Figure 1. Structure of 2; selected bond lengths [pm] and angles [°]:
Si(1)ϪF(1) 158.81(13), Si(1)ϪN(1) 166.6(2), Si(1)ϪO(1) 167.2(2),
Si(1)ϪC(1) 186.3(2), Si(1)ϪSi(2) 245.56(10), Si(2)ϪN(1) 169.1(2),
Si(2)ϪO(1) 170.2(2), Si(2)ϪC(7) 188.3(2); F(1)ϪSi(1)ϪN(1)
111.17(9), F(1)ϪSi(1)ϪO(1) 111.30(8), N(1)ϪSi(1)ϪO(1) 87.15(9),
F(1)ϪSi(1)ϪC(1)
O(1)ϪSi(1)ϪC(1)
114.70(8),
114.78(9),
N(1)ϪSi(1)ϪC(1)
N(1)ϪSi(2)ϪO(1)
114.73(9),
85.40(10),
Si(1)ϪO(1)ϪSi(2) 93.42(10), Si(1)ϪN(1)ϪSi(2) 94.03(10)
Disilylation of the aminosilanol is possible by starting
from the dilithium derivative according to Equation (5):
Crystal Structure of 4
The lithium compound 4 is obtained in high yields
[Equation (6)] from the reaction of 2 with BuLi, thus con-
firming the structure of 4.
1890
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894

1-Oxa-3-aza-2,4-disilacyclobutanes
FULL PAPER
Table 1. Geometric parameters of [R2SiϪX]2 four-membered rings;
X ϭ CR2Ј, NRЈ and O
SiϪX [pm]
Si···Si [pm]
[a]
[H2SiϪC(CMe3)2]2
190.3
188.8
171.1
170.6
167.0
170.7
270.3
259.2
245.0
241.3
239.0
237.8
237.2
[b]
[H2SiϪCH2]2
[Cl2SiϪNCMe3]2
[c]
[d]
[F2SiϪNCMe3]2
[e]
[Mes2SiϪO]2
[f]
[F2SiϪNSiMe(CMe3)2]2
4[g]
[b]
[a] Crystal structure, see ref.[18]
Ϫ
Gas-phase structure, see ref.[19]
[c]
[d]
Ϫ
Crystal structure, see ref.[20]
Ϫ
Crystal structure, see ref.[17]
This work.
Gas-phase structure, see
[e]
[g]
[f]
ref.[20]
ref.[21]
Ϫ
Ϫ
Ϫ
Crystal structure, see
Figure 2. Structure of 4; selected bond lengths [pm] and angles
[°]: Si(1)ϪF(1) 161.8(4), Si(1)ϪO(1) 166.7(5), Si(1)ϪN(1) 172.1(6),
Si(1)ϪC(1) 187.6(7), Si(1)ϪSi(2) 237.2(3), Si(2)ϪO(1) 169.6(5),
Si(2)ϪN(1) 174.3(6), Si(2)ϪC(8) 190.1(8), Li(1)ϪN(1) 195.1(12),
Li(1)ϪN(1Ј) 203.5(13), Li(1)ϪLi(1Ј) 232(2), N(1)ϪLi(1Ј) 201.5(13),
Si(1Ј)ϪF(1Ј) 160.5(5), Si(1Ј)ϪO(1Ј) 166.7(5), Si(1Ј)ϪN(1Ј)
172.9(6),
Si(1Ј)ϪSi(2Ј)
237.3(3),
Si(2Ј)ϪO(1Ј)
169.8(5),
Si(2Ј)ϪN(1Ј) 173.5(6), Li(1Ј)ϪN(1Ј) 195.4(12); F(1)ϪSi(1)ϪO(1)
110.8(2), F(1)ϪSi(1)ϪN(1) 109.1(2), O(1)ϪSi(1)ϪN(1) 92.6(3),
O(1)ϪSi(1)ϪLi(1Ј) 102.1(3), N(1)ϪSi(1)ϪLi(1Ј) 37.9(3), O(1)Ϫ
Si(2)ϪN(1) 90.9(3), N(1)ϪLi(1)ϪN(1Ј) 107.7(6), N(1)ϪLi(1)Ϫ
Li(1Ј) 55.5(4), Si(1)ϪN(1)ϪSi(2) 86.4(3), Li(1)ϪN(1)ϪLi(1Ј)
71.5(5), Si(1)ϪO(1)ϪSi(2) 89.7(2), O(1Ј)ϪSi(2Ј)ϪN(1Ј) 91.1(3),
In the analogous reaction of 4 with Me3SiCl, however, we
isolated the silyl-substituted compound 5, which was also
obtained from the reaction of 4 and Me3SiϪOϪSO2ϪCF3
[Equation (8)].
N(1Ј)ϪLi(1Ј)ϪN(1)
108.4(6),
Si(1Ј)ϪN(1Ј)ϪSi(2Ј)
86.5(3),
Li(1Ј)ϪN(1Ј)ϪLi(1) 71.0(5), Si(1Ј)ϪO(1Ј)ϪSi(2Ј) 89.7(2)
Compound 4 crystallizes from n-hexane as a dimer in
the space group C2/c (Figure 2) Again the crystal structure
shows some irregularities. The dimer of 4 is formed from a
four-membered (LiϪN)2 ring system, which is not entirely
planar but folded by 10.7° across the Li···Li line. The
SiϪOϪSiϪN rings have an angle of 86° to the central
(LiN)2 ring and of 5.8° to each other. The tert-butyl groups
and therefore the aryl group and the fluorine atom are in
cis positions. The sum of the angles around C(1) amounts
to 355.1°. In contrast to compound 2, the SiϪO distances
here are shorter than the SiϪN distances. Now the ring
angles at Si(1) (92.6°) and Si(2) (90.9°) are above 90° and
the angles at O(1) (89.7°) and N(1) (86.4°) are smaller than
90°. This brings the Si(1) and Si(2) atoms into a close
approximation. The Si···Si nonbonding distance in the ring
is only 237.2 pm, which as far as we are aware is the shortest
nonbonding Si···Si contact found so far. The transannular
O···N distance is found to be 245.1 pm. The bonding prop-
erties of such small four-membered rings containing two
opposite silicon atoms have been investigated by various
theoretical methods[5,13Ϫ16]. Table 1 shows examples of
known rings. The presence of a transannular σ bond has
been excluded, in agreement with the very small Si···Si
coupling constant.[17] Grev and Schäfer have explained the
short Si···Si contacts in terms of an ‘‘unsupported π bond’’,
which lies in the plane of the ring.[15]
Figure 3. Structure of 5; selected bond lengths [pm] and angles [°]:
Si(1)ϪO(1) 167.56(12), Si(1)ϪN(1) 177.41(14), Si(1)ϪC(1)
189.9(2), Si(1)ϪC(5) 190.4(2), Si(1)ϪSi(2) 244.53(7), Si(2)ϪF(1)
159.38(10), Si(2)ϪO(1) 165.32(12), Si(2)ϪN(1) 175.26(14),
Si(3)ϪN(1) 174.80(14); O(1)ϪSi(1)ϪN(1) 88.07(6), F(1)ϪSi(2)Ϫ
O(1) 113.60(6), F(1)ϪSi(2)ϪN(1) 107.73(6), O(1)ϪSi(2)ϪN(1)
89.51(6), Si(3)ϪN(1)ϪSi(2) 137.28(8), Si(3)ϪN(1)ϪSi(1) 128.32(8),
Si(2)ϪN(1)ϪSi(1) 87.79(6), Si(2)ϪO(1)ϪSi(1) 94.54(6)
The bulky groups at this lithiated fluorine-containing
ring system motivated us to test the possibility of a LiF
elimination. In the eighties and nineties we were successful
in the preparation of iminosilanes in the following reac-
tion [Equation (7)]:
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894
1891

U. Klingebiel, M. Noltemeyer
FULL PAPER
1-[Aminodi(tert-butyl)]-3-{[2,4,6-tri(tert-butyl)phenyl]difluoro}1,3-
disiloxane (1): To a solution of (Me3C)2Si(NH2)OLi (5.4 g, 0.03
mol) in 50 mL THF was slowly added at room temperature 2,4,6-
(CMe3)3C6H2SiF3 (9.9 g, 0.03 mol) in 20 mL THF. The reaction
mixture was refluxed for 1 h and cooled to room temperature.
Compound 1 was separated from LiF by condensing into a cooled
trap in vacuo and then distilled to give a pure sample, which crys-
tallized. Ϫ Yield 88%, b.p. 155 °C/0.03 mbar, m.p. 88 °C. Ϫ 1H
NMR: δ ϭ 1.00 (SiCMe3), 1.35 (4-C6CMe3), 1.54 (2,6-C6CMe3),
7.44 (C6H2). Ϫ 13C NMR: δ ϭ 20.05 (SiC), 27.95 (SiCC3), 31.36
Crystal Structure of 5
Crystals of 5 were obtained from a THF solution. It crys-
tallizes in the space group Pbcn (Figure 3). The ring system
of 5 resembles the ring system of 2. The ring angles at the
Si atoms are smaller than 90° and the angles at the N and
O atoms are larger, although in 5 the SiϪN bonds are much
longer than in 2 and than the SiϪO bonds. The transannu-
lar Si···Si distance is 244.5 pm. Compound 5 has a planar
(OϪSiϪNϪSi) four-membered ring. The sum of the angles
around the N atom is 353.39°, indicating a slightly trigonal
environment. The C(21) atom deviates slightly from the
plane, as well [ΣC(21) ϭ 356.26°]. The angle between the
four-membered ring and Si(3) amounts 21.3°.
5
(4-C6CC3) 33.45 (t, JCF ϭ 2.7 Hz, 2,6-C6CC3), 34.96 (4-C6C),
39.01 (2,6-C6C), 117.53 (t, 2JCF ϭ 23.7 Hz, F2SiC), 123.07 (3,5-C6),
152.05 (4-C6), 160.81 (t, 3JCF ϭ 1.3 Hz, 2,6-C6). Ϫ 19F NMR: δ ϭ
46.7. Ϫ 29Si NMR: δ ϭ Ϫ73.50 (t, JSiF ϭ 248.9 Hz, SiF2), Ϫ7.66
(SiNH2). Ϫ MS (EI): m/z (%) ϭ 470 (1) [M Ϫ CH3]ϩ, 428 (28) [M
Ϫ C(CH3)3]ϩ. Ϫ C26H49F2NOSi2 (485.85): calcd. C 64.28, H 10.16;
found C 64.42, H 10.34.
Experimental Section
1-Oxa-3-aza-2,4-disilacyclobutane (2): A solution of 1 (4.8 g, 0.01
mol) in a mixture of 50 mL n-hexane and 5 mL THF was treated
with 6.25 mL of nBuLi (1.6  solution in n-hexane, 0.01 mol). The
reaction occurred at room temperature. After stirring for 2 h the
All experiments were performed in oven-dried glassware using
standard inert atmosphere and vacuum-line techniques. The NMR
spectra were recorded in CDCl3 (1, 3) or C6D6 (2, 4, 5) with SiMe4
solvents were condensed into a cooled trap. Compound 2 crystal-
1
and C6F6 (1H, 13C, 19F, 29Si) as internal and MeNO2 (15N) as ex- lized from n-hexane. Ϫ Yield 90%, m.p. 130 °C. Ϫ H NMR: δ ϭ
5
ternal references. The progress of the reactions was monitored by
19F NMR spectroscopy. The compounds were isolated analytic-
ally pure.
0.60 (SiCMe3), 1.10 (SiCMe3), 1.38 (4-C6CMe3), 1.45 (d, JHF
ϭ
5
1.0 Hz, 2,6-C6CMe3), 1.65 (d, JHF ϭ 1.2 Hz, 2,6-C6CMe3), 7.34
(d, JHF ϭ 1.4 Hz, 3,5-C6H), 7.45 (d, JHF ϭ 1.4 Hz, 3,5-C6H). Ϫ
5
5
Table 2. Crystal data and data collections parameters for 2, 4 and 5
2
4
5
Empirical formula
Molecular mass [g/mol]
Temperature [K]
Wave length [pm]
Crystal system
C26H48FNOSi2
465.83
150(2)
C54H98F2Li2N2O250Si4
979.58
150(2)
71.073
Monoclinic
C2/c
C29H56FNOSi3·0.5THF
538.02
200(2)
71.073
Orthorhombic
Pbcn
71.073
Triclinic
¯
Space group
P1
Unit cell dimensions
a ϭ 1032.6(3) pm
b ϭ 1048.7(3) pm
c ϭ 1332.4(6) pm
α ϭ 89.76(3)°
β ϭ 86.95(4)°
γ ϭ 86.93(2)°
1.4387(8)
a ϭ 4182.3(28) pm
b ϭ 1368.2(9) pm
c ϭ 2968.1(17) pm
α ϭ90°
β ϭ 133.97(3)°
γ ϭ 90°
12.2245(135)
8
1.065
a ϭ 1989.7(3) pm
b ϭ 1633.03(15) pm
c ϭ 2078.4(3) pm
α ϭ 90°
β ϭ 90°
γ ϭ 90°
6.7532(15)
8
1.058
0.166
Volume [nm3]
Z
2
Density (calculated) [Mg/m3]
Absorption coefficient [mmϪ1
F(000)
1.075
0.146
512
]
0.141
4288
2368
Crystal size [mm]
θ range for data collection
Index ranges
1.00 ϫ 1.00 ϫ 1.00
3.56 to 25.00°
Ϫ12 Ͻ h Ͻ 12
Ϫ12 Ͻ k Ͻ 12
Ϫ14 Ͻ l Ͻ 15
6545
5042 [R(int) ϭ 0.0254]
Full-matrix
least-squares on F2
5037/0/295
0.60 ϫ 0.50 ϫ 0.30
3.54 to 20.02°
Ϫ32 Ͻ h Ͻ 40
Ϫ13 Ͻ k Ͻ 13
Ϫ28 Ͻ l Ͻ 28
6935
5690 [R(int) ϭ 0.0631]
Full-matrix
least-squares on F2
5666/0/618
0.80 ϫ 0.70 ϫ 0.60
3.64 to 25.04°
Ϫ23 Ͻ h Ͻ 23
Ϫ19 Ͻ k Ͻ 19
Ϫ24 Ͻ l Ͻ 24
11920
5960 [R(int) ϭ 0.0631]
Full-matrix
least-squares on F2
5950/0/334
1.061
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
1.057
1.061
Final R indices [I Ͼ 2σ(I)]
R1 ϭ 0.0501
wR2 ϭ 0.1312
R1 ϭ 0.0565
wR2 ϭ 0.1401
R1 ϭ 0.0716
wR2 ϭ 0.1688
R1 ϭ 0.1189
wR2 ϭ 0.2237
R1 ϭ 0.0380
wR2 ϭ 0.1020
R1 ϭ 0.0459
wR2 ϭ 0.1116
R indices (all data)
Ϫ3
Ϫ3
Ϫ3
˚
˚
˚
Largest diff. peak and hole
0.532 and Ϫ0.334 e.A
0.598 and Ϫ0.414 e·A
0.283 and Ϫ0.240 e·A
1892
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894

1-Oxa-3-aza-2,4-disilacyclobutanes
FULL PAPER
4
5
13C NMR: δ ϭ 20.94 (d, JCF ϭ 3.6 Hz, SiCC3), 20.97 (SiCC3), 33.25 [d, JCF ϭ 1.46 Hz, 2,6-C6(CC3)], 34.42 (4-C6C), 39.19 (d,
5
2
21.42 (SiCC3), 26.65 (SiCC3) 31.21 (4-C6CC3), 32.93 (d, JCF
ϭ
4JCF ϭ 1.15 Hz, 2,6-C6C2), 121.43 (d, JCF ϭ 36.20 Hz, FSiC),
1.5 Hz, 2,6-C6CC3), 32.98 (d, 5JCF ϭ 0.6 Hz, 2,6-C6CC3), 34.70 (4-
121.64 (d, 3JCF ϭ 1.2 Hz, 2,6-SiC6), 150.80 (4-C6), 159.67 (3,5-C6).
4
4
C6C), 38.97 (d, JCF ϭ 1.1 Hz, 2,6-C6C2), 38.98 (d, JCF ϭ 1.1 Hz,
Ϫ
19F NMR: δ ϭ 57.10. Ϫ 29Si NMR: δ ϭ Ϫ49.03 (d, JSiF
ϭ
2
3
3
2,6-C6C), 122.35 (d, JCF ϭ 35.3 Hz, FSiC), 122.15 (d, JCF
ϭ
326.9 Hz, SiF), Ϫ4.34 (d, 3JSiF ϭ 1.5 Hz, SiMe3), 12.85 (d, JSiF ϭ
3
1.9 Hz, 2,6-C6), 123.12 (d, JCF ϭ 1.8 Hz, 2,6-C6), 151.52 (4-C6), 2.0 Hz, SiCMe3). Ϫ MS (EI): m/z (%) ϭ 537 (12) [Mϩ], 480 (100)
4
4
157.90 (d, JCF ϭ 0.4 Hz ,3,5-C6), 159.78 (d, JCF ϭ 0.3 Hz, 3,5-
[M Ϫ CMe3ϩ]. Ϫ C29H55FNOSi3 (537.02): calcd. C 64.86, H 10.32;
C6). Ϫ 15N NMR: δ ϭ Ϫ339.80 (d, JNF ϭ 3.9 Hz). Ϫ 19F NMR: found C 64.69, H 10.02.
2
δ ϭ 54.5. Ϫ 29Si NMR: δ ϭ Ϫ47.20 (d, JSiF ϭ 313.35 Hz, SiF),
9.78 (d, 3JSiF ϭ 2.32 Hz). Ϫ MS (EI): m/z (%) ϭ 465 (7) [Mϩ], 408
X-ray Structure Determination of 2, 4 and 5: The data in Table 2
(100) [M Ϫ CMe3ϩ]. Ϫ C26H48FNOSi2 (465.85): calcd. C 67.04, H
were collected on a STOE AED2 four circle diffractometer with
Mo-Kα radiation. The structures were solved and refined using the
SHELX program suite.[22] The data of 4 were measured only to a
resolution of Θ ϭ 20 degrees.
Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary publication
nos. CCDC-151335 (2), -151336 (4) and -151337 (5). Copies of the
data can be obtained free of charge on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK [Fax: (internat.) ϩ44-1223/
336-033, E-mail: deposit@ccdc.cam.ac.uk].
10.39; found C 67.39, H 10.70.
1-Di(tert-butyl)-1-{[2,4,6-tri(tert-butyl)phenyl]difluorosilylamino}-3-
[difluoro-2,4,6-tri(tert-butyl)phenyl]-1,3-disiloxane (3): To a solution
of (Me3C)2Si(NH2)OLi (1.8 g, 0.01 mol) in 50 mL THF was added
6.25 mL of nBuLi (1.6  solution in n-hexane). The reaction mix-
ture was heated under reflux for 1 h, cooled to room temperature
and mixed with 2,4,6-(CMe3)3C6H2SiF3 (6.6 g, 0.02 mol) in 20 mL
THF. The mixture was heated under reflux for a further 2 h. The
formation of 3 was monitored by 19F NMR spectroscopy. Com-
pound 3 was separated from LiF by condensing the product and
solvents into a cooled trap in vacuo. It was then distilled in vacuo
and recrystallized from n-hexane to give a pure sample. Ϫ Yield
75%, b.p. 210 °C/0.01 mbar, m.p. 158 °C. Ϫ 1H NMR: δ ϭ 1.12
(SiCMe3), 1.30, 1.31 (4-C6CMe3), 1.47, 1.51 [2,6-C6(CMe3)2] 7.38,
7.40 (C6H2). Ϫ 13C NMR: δ ϭ 21.09 (SiC), 27.61 (SiCC3), 31.11,
Acknowledgments
We are grateful to the Deutsche Forschungsgemeinschaft and
Fonds der Chemischen Industrie for support of this work.
5
31.30 (4-C6CC3), 33.20 (t, JCF ϭ 2.43 Hz, 2,6-C6C3), 33.58 (t,
5JCF ϭ 2.12 Hz, 2,6-C6CC3), 34.68, 34.69 (4-C6C), 38.67, 38.99
2
2
(2,6-C6C2), 116.85 (t, JCF ϭ 23.24 Hz, 1-C6) 119.5 (t, JCF
ϭ
20.18 Hz, 1-C6), 122.78, 122.95 (3,5-C6), 151.73, 151.96 (4-C6),
[1]
L. H. Sommer, L. J. Tyler, J. Am. Chem. Soc. 1954, 76,
3
2
160.67 (t, JCF ϭ 1.3 Hz, 2,6-C6), 160.78 (t, JCF ϭ 1.2 Hz, 2,6-
1030Ϫ1034.
3
C6). Ϫ 19F NMR: δ ϭ 47.40 (OSiF2), 49.37 (d, JHF ϭ 6.45 Hz,
[2]
P. D. Lickiss, Adv. Inorg. Chem. 1995, 42, 147Ϫ262.
K. Ruhlandt-Senge, R. A. Bartlett, M. M. Olmstead, P. P.
NHSiF2). Ϫ 29Si NMR: δ ϭ Ϫ74.09 (t, JSiF ϭ 250.5 Hz, OSiF2),
[3]
3
Power, Angew. Chem. 1993, 105, 459Ϫ461; Angew. Chem. Int.
Ϫ48.32 (t, JSiF ϭ 341.4 Hz, NSiF2), Ϫ5.41 (pquint, JSiF
ϭ
0.91 Hz, SiCMe3). Ϫ MS (EI): m/z (%) ϭ 795 (1) [Mϩ], 738 (100)
[M Ϫ C4H9ϩ]. Ϫ C44H77F4NOSi3 (796.35): calcd. C 66.36, H 9.75;
found C 66.43, H 9.87.
Ed. Engl. 1993, 32, 425Ϫ427.
[4]
R. Murugavel, M. Bhattadarjee, H. W. Roesky, Appl. Or-
ganomet. Chem. 1999, 13, 227Ϫ243.
[5]
O. Graalmann, U. Klingebiel, J. Organomet. Chem. 1984, 275,
C1ϪC4.
Lithium 4,4-di(tert-butyl)-2-fluoro-2-[2,4,6-tri(tert-butyl)phenyl]-1-
oxa-3-aza-2,4-disilacyclobutane (4): A solution of 2 (4.6 g, 0.01 mol)
in 30 mL n-hexane was treated with 6.25 mL of nBuLi (1.6  solu-
tion in n-hexane, 0.01 mol). The lithiation occurred at room tem-
perature, was monitored by 19F NMR spectroscopy, and finished
after 2 h. Compound 4 was separated from solvent in vacuo and
[6]
O. Graalmann, U. Klingebiel, W. Clegg, M. Haase, G. M. Shel-
drick, Angew. Chem. 1984, 96, 904Ϫ905; Angew. Chem. Int. Ed.
Engl. 1984, 23, 891Ϫ892.
[7]
U. Klingebiel, S. Schütte, D. Schmidt-Bäse, in The Chemistry of
Inorganic Ring Systems (Ed.: R. Steudel), Elsevier, Amsterdam,
1992, 75Ϫ99.
D. Schmidt-Bäse, U. Klingebiel, J. Organomet. Chem. 1989,
364, 313Ϫ321.
[8]
1
crystallized from n-hexane as a dimer. Ϫ Yield 95%. Ϫ H NMR:
δ ϭ 1.00, 1.17 (SiCMe3), 1.30 (4-C6CMe3), 1.55, 1.57 (2,6-
[9]
E. Egert, M. Haase, U. Klingebiel, C. Lensch, D. Schmidt, G.
C6CMe3), 7.40 (C6H2). Ϫ 13C NMR: δ ϭ 20.80, 21.07 (SiCC3),
M. Sheldrick, J. Organomet. Chem. 1986, 315, 19Ϫ25.
27.90, 28.07 (SiCC3), 31.24 (4-C6CC3), 33.81 (2,6-C6CC3), 34.59 (4-
[10]
O. Graalmann, U. Klingebiel, M. Meyer, Chem. Ber. 1986,
2
C6C), 39.40 (2,6-C6C2), 122.60 (2,6-C6), 125.26 (d, JCF
ϭ
119, 872Ϫ877.
20.72 Hz, FSiC), 150.92 (4-C6), 161.22 (3,5-C6). Ϫ 19F NMR: δ ϭ
60.53. Ϫ 29Si NMR: δ ϭ Ϫ52.16 (d, JSiF ϭ 248.11 Hz, SiF),
Ϫ1.08 (SiC2).
[11]
S. Walter, U. Klingebiel, M. Noltemeyer, Chem. Ber. 1992,
125, 783Ϫ788.
K. Dippel, U. Klingebiel, G. M. Sheldrick, D. Stalke, Chem.
[12]
Ber. 1987, 120, 611Ϫ616.
[13]
Y. Appeloig, in The Chemistry of Organic Silicon Compounds
4,4-Di(tert-butyl)-2-fluoro-3-trimethylsilyl-2-[2,4,6-tri(tert-butyl)-
phenyl]-1-oxa-3-aza-2,4-disilacyclobutane (5): Compound 4 (4.7 g,
0.01 mol) in 50 mL THF was mixed with Me3SiOSO2CF3 (2.2 g,
0.01 mol). In an exothermic reaction LiOSO2CF3 and 5 were
formed. LiOSO2CF3 was removed by filtration through a frit and
5 crystallized from the THF solution. Ϫ Yield 95%, m.p. 112 °C.
Ϫ 1H NMR: δ ϭ 0.23 (SiMe3), 0.58 (SiCMe3), 1.13 (SiCMe3), 1.26
(Eds.: S. Patai and Z. Rappaport), Part 1, Wiley, Chichester,
1989, p. 1213.
[14]
M. OЈKeefe, G. V. Gibbs, J. Phys. Chem. 1985, 89, 4574.
[15]
R. S. Grev, H. F. Schäfer, III, J. Am. Chem. Soc. 1987, 109,
6577.
[16]
A. Savin, H. J. Flad, H. W. Preuss, H. G. von Schnering, An-
gew. Chem. 1992, 104, 185Ϫ186; Angew. Chem. Int. Ed. Engl.
(4-C6CMe3), 1.45 [d, 6JHF ϭ 1.13 Hz, 2,6-C6(CMe3)2], 7.26 (C6H2).
1992, 31, 185Ϫ186.
4
Ϫ
13C NMR: δ ϭ 4.75 (SiC3), 21.80 (d, JCF ϭ 3.48 Hz, SiCC3),
[17]
R. West, Angew. Chem. 1987, 99, 1231Ϫ1241; Angew. Chem.
22.74 (SiCC3), 26.88 (SiCC3), 27.85 (SiCC3), 31.10 (4-C6CC3),
Int. Ed. Engl. 1987, 26, 1201Ϫ1211.
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894
1893

U. Klingebiel, M. Noltemeyer
FULL PAPER
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[21]
[22]
M. Jendras, Dissertation Univ. Göttingen, 2000.
B. Rempfer, G. Pfafferott, H. Oberhammer, N. Auner, J. E.
B. Tecklenburg, U. Klingebiel, M. Noltemeyer, D. Schmidt-
Bäse, Z. Naturforsch. B: Chem. Sci. 1992, 47, 855Ϫ860.
G. M. Sheldrick, The SHELX-97 manual, Universität
Göttingen, 1997.
[19]
Boggs, Acta Chem. Scand., Ser. A 1988, 42, 352.
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M. Schäfer, H. Oberhammer, Chem. Ber.,/Recueil 1997, 130,
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Received October 3, 2000
[I00401]
1894
Eur. J. Inorg. Chem. 2001, 1889Ϫ1894