Synthesis and Characterization of 2,4,6-Tris((dimethylamino)methyl)phenoxysilicon Compounds

Article abstract of DOI:10.1016/S0022-328X(01)01053-1

A series of 2,4,6-tris((dimethylamino)methyl)phenoxysilicon compounds Σ_4-nSi(OAr)n (Σ = Cl; n = 1 (1), 2 (2); Σ = Me, n = 1 (3), 2 (4); Σ = Me3Si, n = 1 (5), 2 (6), PhSiH_n(OAr)3_3-n (n =2 (7), 1 (8)) and H_nSi(OAr)_4-n (n = 2 (9), 1 (10) has been synthesized by various adapted methods. The compounds were characterized spectroscopically by 29Si-, 1H-, 13C-, 15N-NMR. In solution the extent of Si...N bond formation and coordination in these compounds is determined from the 29Si-NMR (and 15N) chemical shifts and ¹J_Si-H. The silicon center is tetracoordinated in 3-6, pentacoordinated in 1, 2, 7, 8 and hexacoordinated [4+2] in 9. The 1H-NMR features are consistent, in all cases, with dynamic coordination mode of the o-NMe2 groups in solution at room temperature. The solid-state structures of the lithium phenolate and of compounds 6 and 9 have been determined by X-ray diffraction. The trimeric structure of ArOLi contains an Li3O3-ring that is almost perfectly planar; the structures of 6 and 9 confirm no N -> Si contact in 6 and a bicapped tetrahedral silicon in 9.

Full text of DOI:10.1016/S0022-328X(01)01053-1

Journal of Organometallic Chemistry 636 (2001) 96–107
www.elsevier.com/locate/jorganchem
Synthesis and characterization of
2,4,6-tris((dimethylamino)methyl)phenoxysilicon compounds
Aman Akkari-El Ahdab, Ghassoub Rima, Heinz Gornitzka, Jacques Barrau *
He´te´rochimie Fondamentale et Applique´e, UMR-5069 du CNRS, Uni6ersite´ Paul-Sabatier, 118, route de narbonne,
31062 Toulouse Cedex 4, France
Received 2 March 2001; accepted 1 June 2001
Dedicated to Professor O.M. Nefedov on the occasion of his 70th birthday.
Abstract
A series of 2,4,6-tris((dimethylamino)methyl)phenoxysilicon compounds S4−nSi(OAr)n (S=Cl; n=1 (1), 2 (2); S=Me, n=1
(3), 2 (4); S=Me3Si, n=1 (5), 2 (6)), PhSiHn(OAr)3−n (n=2 (7), 1 (8)) and HnSi(OAr)4−n (n=2 (9), 1 (10)) has been synthesized
1
by various adapted methods. The compounds were characterized spectroscopically by 29Si-, H-, 13C-, 15N-NMR. In solution the
extent of Si···N bond formation and coordination in these compounds is determined from the 29Si-NMR (and 15N) chemical shifts
1
and JSiꢀH. The silicon center is tetracoordinated in 3–6, pentacoordinated in 1, 2, 7, 8 and hexacoordinated [4+2] in 9. The
1H-NMR features are consistent, in all cases, with dynamic coordination mode of the o-NMe2 groups in solution at room
temperature. The solid-state structures of the lithium phenolate and of compounds 6 and 9 have been determined by X-ray
diffraction. The trimeric structure of ArOLi contains an Li3O3-ring that is almost perfectly planar; the structures of 6 and 9
confirm no N“Si contact in 6 and a bicapped tetrahedral silicon in 9. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Silicon; Hypercoordination; NMR; Crystal structure
phenoxy ligand with two ortho-chelating tertiary amine
substituents that can, through intramolecular dynamic
1. Introduction
coordination, stabilize divalent species (ArO)2M and
During the past 15 years there has been an explosive
their
complexes
(ArO)2MM%Ln
(ArO=2,4,6-
growth of research interest into chemistry of in-
tramolecularly coordinated organosilicon compounds;
these compounds have a varied chemistry that is signifi-
cantly different from that of their tetravalent counter-
parts. Numerous structural types in which Y“Si
intramolecular coordination due to a C,Y-chelating
ligand (Y=heteroatom-containing substituent) have
been developed, particularly ortho-silylated benzyl-
diorganoamines [1,2], but less attention has been paid
to compounds containing O,Y-chelating ligands. The
only previously reported such structures, bearing the
OꢀC(R)ꢁNꢀNMe2 ligand [3], are hexacoordinate bis-
chelates with near-octahedral geometries. We have al-
ready demonstrated the interesting potential of a
[(CH3)2NCH2]3C6H2O; M=Ge, Sn, Pb; M%=Fe, Cr,
W) [4]. In the present study we have focused on new
silicon compounds with as supporting ligand this phen-
oxy ligand bearing in 2,4,6 positions (dimethyl-
amino)methyl groups suitable for intramolecular coor-
dination, S4−nSi(OAr)n and RSiHn(OAr)3−n (S=Cl,
Me, Me3Si; R=Ph, ArO; n=1, 2).
2. Results and discussion
2.1. Synthesis
2.1.1. Chlorosilanes Cl3SiOAr (1) and Cl2Si(OAr)2 (2)
We first considered obtaining the trichloro[2,4,6-tris-
((dimethylamino)methyl)phenoxy]silane Cl3SiOAr (1)
and the dichlorobis[2,4,6-tris((dimethylaminomethyl)-
* Corresponding author. Tel.: +33-5-61556172; fax: +33-5-
61558204.
E-mail address: barrau@chimie.ups-tlse.fr (J. Barrau).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01053-1

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
97
The solid-state structure of (ArOLi)3 determined by
single crystal diffraction is shown in Fig. 1; the inter-
atomic distances and the characteristic angles are re-
ported in Table 1. This study reveals that this
compound is also trimeric in the solid state; (ArOLi)3
crystallized in the monoclinic system, space group P21/
c, with parameters: a=20.836(4), b=27.613(8), c=
,
8.798(2) A; h=90°; i=97.26(2)°; k=90° and
zcalc=1.077 g cm−3 for Z=4. The polydendate ary-
loxy ligand confers to this compound a six-membered
practically planar cyclic (LiO)3 structure; every atom of
lithium is connected to two aryloxy groups by two
oxygen atoms and two nitrogen atoms and presents a
tetrahedral environment. The LiꢀO bond lengths (aver-
,
age value: 1.87 A; the smallest being Li(2)ꢀO(2)=
,
1.854(4) A) are among the shortest known [5,6],
Fig. 1. Solid-state structure of (ArOLi)3.
,
whereas the LiꢀN bond lengths (average value: 2.24 A;
,
the longest being Li(2)ꢀN(6)=2.410 A) are relatively
phenoxy]silane Cl2Si(OAr)2 (2) by the classic method of
synthesis of ethers by alcoxylation by achieving the
direct action of the 2,4,6-tris((dimethylamino)methyl)-
phenolate of lithium on the tetrachlorosilane.
longer than that observed in typical tetracoordinated
lithium compounds. The CipsoꢀO are relatively short
,
(average value: 1.32 A); the short distances LiꢀO and
CipsoꢀO should be connected to a quasi-aromaticity of
the cycle Li3O3 [6,7]. This structure is comparable to
that reported for 4-Me-2,6-(Me2NꢀCH2)2ꢀC6H2OLi
[6,8]. To our knowledge, (ArOLi)3 is the second exam-
ple of a trinuclear structure for a phenolate of lithium
described to date in the literature; its specific originality
is to be associated with the presence of a third poten-
tially coordinating CH2NMe2 group in para position on
every aryloxy group. In the solid state, the CH2N
hydrogen atoms, as well as the NMe2 methyl groups of
each of the six equivalent CH2NMe2 groups participat-
ing in the coordinations with the three atoms of
lithium, are diastereotopic; however, in solution, they
appear in the 1H-NMR spectrum as singlets
The 2,4,6-tris((dimethylamino)methyl)phenolate of
lithium [ArOLi] was obtained by the action of one
equivalent of nBuLi on the corresponding alcohol in
ether; ArOLi is soluble in ether and was conveniently
purified by crystallization at −20 °C from ether/pen-
tane solution (50/50). Molecular weight determination
(cryoscopy in benzene) showed ArOLi to be trimeric in
solution. Its mass spectrum also displays the same
cluster structure (ArO)3Li3 in the gas phase. The elec-
tron-impact mass spectrum shows six fragment ions
corresponding to [(ArO)2Li3]+, [(ArO)Li2]+, Li+,
[(ArO)3Li3−NMe2]+,
[(ArO)2Li2−NMe2]+,
and
[ArOLi−NMe2]+; the most abundant species is
[(ArO)Li2]+.. Thus the fragmentation leads to the re-
lated species Lix(ArO)x, which lose an NMe2 group.
[l(CH2N)=3.33 ppm
(12H);
l(CH3)=1.92 ppm
(36H)]. This equivalence could be due to the phe-
Table 1
,
Selected bond distances (A) and angles (°) for (ArOLi)3
Bond distances
Li(1)ꢀO(2)
Li(1)ꢀO(1)
Li(1)ꢀN(3)
Li(1)ꢀN(4)
1.864(4)
1.885(4)
2.190(4)
2.254(4)
Li(2)ꢀO(2)
Li(2)ꢀO(3)
Li(2)ꢀN(9)
Li(2)ꢀN(6)
1.854(4)
1.902(4)
2.173(4)
2.410(4)
Li(3)ꢀO(1)
Li(3)ꢀO(3)
Li(3)ꢀN(7)
Li(3)ꢀN(1)
1.859(4)
1.869(4)
2.201(4)
2.234(4)
Bond angles
O(2)ꢀLi(1)ꢀO(1)
O(2)ꢀLi(1)ꢀN(3)
O(1)ꢀLi(1)ꢀN(3)
O(2)ꢀLi(1)ꢀN(4)
O(1)ꢀLi(1)ꢀN(4)
N(3)ꢀLi(1)ꢀN(4)
O(1)ꢀLi(3)ꢀO(3)
O(1)ꢀLi(3)ꢀN(7)
O(3)ꢀLi(3)ꢀN(7)
Li(3)ꢀO(1)ꢀN(7)
Li(3)ꢀO(3)ꢀLi(2)
113.0(2)
O(2)ꢀLi(2)ꢀO(3)
O(2)ꢀLi(2)ꢀN(9)
O(3)ꢀLi(2)ꢀN(9)
O(2)ꢀLi(2)ꢀN(6)
O(3)ꢀLi(2)ꢀN(6)
N(9)ꢀLi(2)ꢀN(6)
O(1)ꢀLi(3)ꢀN(1)
O(3)ꢀLi(3)ꢀN(1)
N(7)ꢀLi(3)ꢀN(1)
Li(2)ꢀO(2)ꢀLi(1)
111.99(18)
127.3(2)
94.20(18)
90.50(17)
129.7(2)
107.08(15)
95.26(16)
130.94(19)
106.14(17)
126.50(18)
124.35(19)
95.32(16)
93.96(16)
124.11(18)
108.74(17)
109.27(19)
123.59(19)
94.83(16)
129.26(16)
129.75(17)

98
A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
(Et2N)2SiCl2+ArOH−ꢀꢀ(Eꢀt2ꢀNꢀHꢀ·ꢀHꢀCꢂl)(ArO)2SiCl2
+(ArO)2Si(Cl)NEt2+(ArO)3SiNEt2+Et2NH
(1)
The di- and tri-chlorosilanes, isolated as white solids
(by precipitation in hexane), were fully characterized by
the usual spectroscopic methods (1H-, 13C-, 29Si-NMR)
and mass spectrometry. It is noteworthy that
(ArO)2SiCl2 suffers decomposition in a few hours, even
in an inert atmosphere, to give a green–black uniden-
tified solid that is insoluble in all solvents. All attempts
at crystallization have failed.
Scheme 1.
2.1.2. Silanes R3SiOAr (3,5) and R2Si(OAr)2 (4, 6)
Following the same synthetic method, silanes
Me3SiOAr (3), Me2Si(OAr)2 (4), (Me3Si)3SiOAr (5) and
(Me3Si)2Si(OAr)2 (6) were prepared by alcoholysis by
the phenol of the corresponding aminosilanes [Eq. (2)].
These reactions gave high yields; the expected com-
pounds 3 and 4 were isolated in the pasty form, and the
derivatives 5 and 6 were obtained pure by crystalliza-
tion (in pentane, at −20 °C) as white solids. All these
derivatives are soluble in common organic solvents and
were characterized by multinuclear NMR analysis,
mass spectrometry and elementary analysis.
Scheme 2.
nomenon of LiꢀN dissociation–association, with rapid
rotation around the CipsoꢀO bond.
One or two equivalents of (ArOLi)3 were added,
at ambient temperature, to a diethyl ether solution
of tetrachlorosilane. The yields in chlorosilanes
Cl(4−n)Si(OAr)n of these reactions are limited (B40%);
in fact, these reactions, along with chlorosilanes
Cl(4−n)Si(OAr)n, afford a solid phase that mass spectro-
R4−nSi(NMe2)n+ArOH ꢀꢀꢀꢀꢀꢀꢂ R4−nSi(OAr)n
(2)
metric analysis showed to be
a
mixture of
−nMe NH
2
Cl(4−n)Si(OAr)n and of the cluster (ArO)2Li3Cl. The
cluster (ArO)2Li3Cl was identified by comparison with
an authentic sample obtained by mixing lithium pheno-
late and lithium chloride in diethyl ether (Scheme 1).
The low yields in Cl(4−n)Si(OAr)n of the previous
syntheses and the difficulties arising from the formation
of by-products, which cannot be isolated, prompted us
to explore alternate methods of preparing the di- and
tri-chlorated derivatives. (i) With numerous exchange
reactions between compounds with SiꢀCl and SiꢀO
bonds having been reported, we investigated the redis-
tribution reactions between the silicon tetrachloride
and the [2,4,6-tris((dimethylamino)methyl)phenoxy]tri-
methylsilane Me3SiOAr to obtain the Cl4−nSi(OAr)n
structures. Me3SiOAr, obtained by treatment of one
equivalent of phenolate of lithium by one equivalent of
methyltrichlorosilane in ether at ambient temperature,
was submitted to the action of SiCl4 in a sealed tube, in
the absence of solvent, at 80 °C for 12 h (Scheme 2). By
this method the expected derivatives Cl4−nSi(OAr)n
(n=1, 2) can be obtained with good yields (ꢀ80%).
(ii) The known extreme sensitivity of the silicon–nitro-
gen bond to reagents with some acidic character
prompted us to carry out the reaction of the aminosi-
lane Cl2Si(NEt2)2 with the alcohol ArOH. The reaction
is effected in refluxing toluene, the diethylamine by-
product being eliminated by distillation. This reaction
R=Me (n=1, 3; 2, 4); Me3Si (n=1, 5; 2, 6).
2.1.3. Phenylhydrosilanes of Ph(ArO)SiH2 (7) and
Ph(ArO)2SiH (8)
The usual method of alcoxy- and aryloxy-silanes
synthesis by dehydrocondensation reactions between
silicon hydrides and alcohols did not allow isolation of
the hydrosilanes Ph(ArO)SiH2 and PhSiH(OAr)2 in a
selective way. The reactions in various solvents of
PhSiH3 with ArOH in variable stoichiometric quantities
resulted practically always in a mixture of di- and
tri-aryloxysilanes; no traces of monoaryloxysilane were
detected in these reactions. Their quantitative results
are summarized in Table 2.
With access to dihydrosilane Ph(ArO)SiH2 being im-
possible by this method, we considered its synthesis by
means of the silyltriflate Ph(TfO)SiH2, obtained by the
protodearylation reaction of Ph2SiH2 by the trifl-
uoromethanesulfonic acid (TfOH, triflic acid). One
equivalent of ArOH reacts with Ph(TfO)SiH2, in the
presence of triethylamine in toluene at −30 °C, to
produce mainly the dihydrosilane 7, as well as the
1
hydrosilane 8 (relative percent estimated by H-NMR
analysis: 7/8=60/40) (Scheme 3). The two hydrosilanes
could be isolated in pure form by distillation of 7 under
vacuum. They are thermally stable.
produces
a few traces of (ArO)2Si(Cl)NEt2 and
2.1.4. Hydrosilanes (ArO)2SiH2 (9) and (ArO)3SiH (10)
It was also necessary to investigate different methods
of synthesis to obtain (ArO)2SiH2 and (ArO)3SiH in
(ArO)3SiNEt2 in addition to the normal alcoholysis
product (ArO)2SiCl2 [Eq. (1)].

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
99
Table 2
Dehydrocondensation reactions between PhSiH3 and ArOH
PhSiH3 (g [mmol])
ArOH (g [mmol])
Conditions
Solvent
Ether
Products (%)
Ph(ArO)2SiH
T (°C)
Time
PhSi(OAr)3
PhSiH3
ArOH
0.4 [3.77]
0.4 [3.77]
1 [3.77]
1 [3.77]
25
4 h
48 h
41
62
–
–
15
23
44
15
Pentane
25
5 h
24 h
2.5 h
15
18
25
–
–
–
22
27
16
63
55
59
35
25
25
25
0.4 [3.77]
0.2 [1.88]
0.13 [1.25]
1 [3.77]
1 [3.77]
1 [3.77]
–
–
–
15 days
15 days
15 days
63
66
21
–
5
12
–
25
29
63
16
–
pure form. The reactions carried out are summarized in
Scheme 4 and Table 3. Among the different methods
used, the alcoholysis reactions of the silylamines
H2Si(NR2)2 by ArOH (R=Et, Me) worked clearly and
rapidly, giving good yields in (ArO)2SiH2. In all the
other reactions the yields were modest, and consider-
able quantities of by-products were always formed (for-
mation of clusters in the reaction of the phenoxylithium
with H2SiI2; formation of the ionic compound
[(ArO)2SiH]+I− [9] in the direct treatment of H2SiI2 by
ArOH; formation of (ArO)3SiH in several of the reac-
tions). The hydrotriaryloxysilane (ArO)3SiH was easily
made by reacting ArOH with (ArO)2SiH2 in CH2Cl2 at
ambient temperature.
ligands are not coordinated to the silicon, since the
chemical shifts of the Northo nitrogen atoms of the
aryloxy groups are quite comparable to those of Northo
nitrogen atoms of the ArOH alcohol [3: (l=
−350.1 ppm), ArOH: l= −351.1 ppm)]. Single crys-
tals of 6 suitable for X-ray structure analysis were
obtained from pentane. Fig. 2 shows the solid-state
structure of 6, together with the numbering scheme.
Relevant bonds distances and angles are given in Table
5. This structure is comparable to those of trisilanes
previously reported [10], the silicon being at the center
of a tetrahedron. All the SiꢀSi, SiꢀO and SiꢀC distances
correspond to the classic s-bonds around a silicon
atom. The SiꢀSiꢀSi angle (111.26°) is slightly smaller
than those observed in various other trisilanes [11],
whereas the SiꢀOꢀC angles (129.22 and 125.99°) are
slightly more important than those observed in various
silyl ethers; these results could be explained by steric
hindrance of the ArO group.
2.2. NMR, mass, UV–6is spectroscopies and structural
characterization
All the silanes 1–6 are very sensitive to atmospheric
oxygen and moisture; they are stable under a nitrogen
1
atmosphere and were fully characterized by H-, 13C-,
29Si-NMR, IR, UV–vis and mass spectrometry.
2.2.1. Silanes R3SiOAr (3, 5) and R2Si(OAr)2 (4, 6)
The characteristic spectroscopy data of compounds
3–6 are reported in Table 4, together with the 29Si-
NMR chemical shifts of their respective phenoxylated
analogs.
1
The H-NMR spectra at 25 °C of silanes 3–6 reveal
Scheme 3.
that the four o-NMe2 groups are magnetically equiva-
lent (broad singlet) [l=2.16 ppm (3); l=2.16 ppm (4);
l=2.19 ppm (5); l=2.16 ppm (6)]; a singlet is also
observed as signal for the protons of the corresponding
CH2N groups. Their 29Si-NMR spectra all display a
singlet, which is in the same range as those observed for
the tetracoordinated corresponding phenoxylated
analogs Me3SiOPh, Me2Si(OPh)2, (Me3Si)3SiOPh and
(Me3Si)2Si(OPh)2. Compounds 3–6 should, therefore,
not present Si···N interaction in solution. 15N-NMR
also supports that the Northo nitrogen atoms of the ArO
Scheme 4.

100
A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
Table 3
Reactions carried out for synthesis of the hydrosilanes 9 and 10
Reagents
Conditions
Products (%)
H2SiI2+2ArOLi
Ether
THF
25 °C
65 °C
12 h
2 h
Traces (ArO)2SiH2
(ArO)2SiH2 (17%)+(ArO)2Li3I+traces [(ArO)2SiI]+ (MS)
H2SiI2+2ArOH
C6D6
25 °C
5 min
[(ArO)2SiH]+ I− (15%)
H2SiI2+2ArOH/Et3N
Et3N
Et3N
25 °C
89 °C
12 h
1 h
(ArO)2SiH2 (20%)+(ArO)3SiH (31.5%)
(ArO)3SiH (51%)
H2Si(NMe2)2+2ArOH
Pentane
Pentane
Pentane
25 °C
reflux
35 °C
45 min
2 h
3 h
(ArO)2SiH2 traces
(ArO)2SiH2 (42%)+(ArO)3SiH (18%)+ArOH (21%)
(ArO)3SiH (40%)
H2Si(NEt2)2+2ArOH
H2Si(NMe2)2+2ArOH
H2Si(NEt2)2+3ArOH
CDCl3
CDCl3
CDCl3
25 °C
25 °C
25 °C
5 min
10 min
24 h
(ArO)2SiH2 (95%)
(ArO)2SiH2 (78%)
(ArO)3SiH (81%)
Table 4
Selected 29Si- and 1H-NMR data for silanes R2Si(OAr)2 and R3SiOAr 3–6
Compounds
l
29Si [CDCl3] (ppm)
Dl (ppm)
1H-NMR (l, ppm)
o-NMe2
p-NMe2
p-CH2N
o-CH2N
(3)
(5)
(4)
(6)
Me3SiOAr
Me3SiOPh
18.19
18.8
0.61
1.3
2.16
2.13
2.08
2.15
2.20
3.34
3.44
(Me3Si)3SiOAr
(Me3Si)3SiOPh
−15.9, −2.8
[−15.7, −1.5]
2.19
2.16
2.18
3.35
3.32
3.37
3.36
3.50
3.56
Me2Si(OAr)2
Me2Si(OPh)2
−3.02
−1.62
1.4
(Me3Si)2Si(OAr)2
(Me3Si)2Si(OPh)2
−20.5, 8.0
[−20.4, 9.71]
1.71
At ambient temperature, the 29Si-NMR spectra of
compounds 1 and 2 exhibit resonances at −30.8 ppm
and −42.4 ppm respectively (unfortunately the 29Si
chemical shifts of the corresponding trichlorophenoxy-
and dichlorophenoxy-silanes are unknown). The 1H-
NMR spectra of 1 and 2 both reveal the equivalence of
the o-NMe2 groups [(1) l=2.16 ppm and (2) l=
2.13 ppm]; a singlet is also observed for the protons of
the corresponding CH2N groups [(1) l=3.57 ppm and
The analysis of mass spectroscopy of (Me3Si)2-
Si(OAr)2 obtained under 70 eV electronic impact re-
veals the peaks corresponding to the molecular ion
M+ (17%) and to the fragmentations [M−Me3Si]+,
’
[M−Me3Si−3Me]+, [M−2Me3Si]+, [M−OAr]+
and [M−Me3SiOAr]+ (relative intensities 42%, 31%,
2%, 100% and 6% respectively). The most intense peak
corresponds to [M−OAr], which suggests the forma-
tion of the silicon cation [(Me3Si)2Si(OAr)]+, and which
could be greatly stabilized by intramolecular
coordination.
The UV spectrum of (Me3Si)2Si(OAr)2, in cyclohex-
ane, presents a strong absorption at umax=284 nm
(m=31.623×104) (the characteristic absorption due to
the trisilane fragment is hidden by this strong band).
2.2.2. Chlorosilanes 1 and 2
In these two cases the 1H- and 29Si-NMR studies
allowed us to discuss the coordination around the
central atom; the spectroscopic values are reported in
Table 6.
Fig. 2. Solid-state structure of (Me3Si)2Si(OAr)2 (6).

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
101
Table 5
,
Selected bond lengths (A) and angles (°) for 6
Bond distances
Si(1)ꢀO(1)
Si(1)ꢀO(2)
Si(1)ꢀSi(2)
Si(1)ꢀSi(2)
1.666(19)
1.666(19)
2.363(10)
2.366(10)
Bond angles
O(2)ꢀSi(1)ꢀO(1)
O(2)ꢀSi(1)ꢀSi(2)
O(1)ꢀSi(1)ꢀSi(2)
O(2)ꢀSi(1)ꢀSi(3)
O(1)ꢀSi(1)ꢀSi(3)
Si(2)ꢀSi(1)ꢀSi(3)
106.94(9)
108.84(8)
110.61(7)
111.08(7)
108.03(7)
111.26(3)
Scheme 5.
coordination and the other to two free o-dimethy-
lamino groups far from the silicon atom; this is consis-
tent with the two limiting forms represented in Scheme
5. It was impossible on lowering the temperature fur-
ther (−75 °C) to observe rigid coordination of NMe2
units to silicon, which should have implied
diastereotopic methyl groups at nitrogen and an AB
system for the corresponding benzylic phenyl CH2N
protons. We did mean to elucidate physically the degree
of coordination of the NMe2 groups to the silicon
atom, but our repeated efforts to study these com-
pounds in the solid state by X-ray crystallography have
been unsuccessful.
(2) l=3.54 ppm]. These analytical data are consistent
with either (i) a structure in which there is no in-
tramolecular coordination of the o-NMe2 units to sili-
con, thus allowing inversion of the nitrogen atom, or
(ii) a dynamic N···M···N coordination–decoordination
process involving the four o-NMe2 groups. Such ‘flip-
flop’ intramolecular coordination modes have already
been reported for tetravalent tin and silicon derivatives
[12–14]. In order to attempt to specify the nature and
strength of possible coordination of nitrogen atoms to
1
the silicon atom, a variable-temperature 29Si- and H-
NMR study of compound 2 was carried out in CD2Cl2.
At −60 °C the 29Si signal drops to −52 ppm, suggest-
ing more hypercoordination as expected. More infor-
1
2.2.3. Hydrosilanes Ph(ArO)SiH2 (7), Ph(ArO)2SiH (8)
and (ArO)2SiH2 (9)
mation is given by the H-NMR spectrum at −60 °C,
which exhibits two large singlets of equal intensity for
the o-N methyl protons (l=2.11 and 2.12 ppm). Even
though the magnetic non-equivalence of the two types
of o-NMe2 group observed at −60 °C could be at-
tributed to the hindrance to OꢀSiꢀO rotation, these
observations seem, rather, (i) to suggest that at this
temperature the hypercoordination may be important
and (ii) to confirm the hypothesis of the dynamic
N···Si···N coordination. The non-equivalence of the
protons of the o-NMe2 groups might indicate that, at
this low temperature, the flip-flop coordination process
The silanes 7–9 have been characterized by 1H-, 13C-,
15N-, 29Si-NMR, IR and mass spectrometry; the main
spectroscopic characteristics are reported in Table 7.
1
2.2.3.1. Phenylhydrosilanes 7 and 8. H-NMR spectra in
CDCl3, at room temperature, display in both cases a
singlet [l=1.95 ppm (8), l=2.08 ppm (7)] for the pro-
tons of the two (7) or four (8) o-NMe2 groups; a single
broad signal is also observed for the protons of the
1
corresponding CH2N groups. These H-NMR observa-
1
is slow enough that we can observe in H-NMR, along
tions can be rationalized by a non-coordination or a
rapid coordination–decoordination process N···Si···N
of the o-N atoms to the silicon atom. With an increase
in the number of coordination at silicon generally in-
with the p-dimethylamino group, two types of o-
dimethylamino group. One type probably might corre-
spond to two o-dimethylamino groups in dynamic
Table 6
Selected 29Si- and 1H-NMR data a for chlorosilanes Cl3Si(OAr) and Cl2Si(OAr)2
Compounds
l
29Si (CD2Cl2, ppm)
1H-NMR (CD2Cl2, ppm)
o-NMe2
p-NMe2
p-CH2N
o-CH2N
Cl3Si(OAr), 25 °C
Cl2Si(OAr)2, 25 °C
Cl2Si(OAr)2, −60 °C
−30.80
−42.40
−51.42
2.16 (s*)
2.13 (s*)
2.11 (s*), 2.12 (s*)
2.18 (s*)
2.16 (s*)
2.21 (s*)
3.35 (s*)
3.32 (s*)
3.30 (s*)
3.57 (s*)
3.54 (s*)
3.53 (s*), 3.48 (s*)
a s*: broad singlet.

102
A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
ducing a displacement at upfield of the 29Si-NMR
chemical shifts [15,16], we compared the 29Si-NMR
chemical shifts of silanes 7 and 8 with those of their
corresponding tetracoordinated silicon phenoxylate
analogs PhSiH(OPh)2 and PhSiH2(OPh). The 29Si-
NMR chemical shifts of silanes 7 and 8 are upfield
(Dl:10 ppm) compared with those of their respective
analogs Ph(PhO)2SiH and Ph(PhO)SiH2. The 29SiꢀH
coupling constants are increased compared with those
observed for the corresponding species with non-func-
tionalized ligands [DJ=14 Hz for (7) and DJ=30 Hz
for the silane (8)]. These data are consistent with a
hypercoordination of the silicon atom [15,17–22], pre-
sumably five or [4+1], in the silanes 7 and 8. The
equivalence of the o-dimethylamino groups in 1H-
NMR is, therefore, characteristic of an N···Si···N ‘flip-
flop’ dynamic coordination process. Furthermore, it is
worth noting that a weak downfield shift for the 15N-
NMR resonance of the o-NMe2 groups of 7 and 8 is
observed compared with that observed for ArOH (l=
−348.5 (7); l = −350.0 (8); l = −351.5 ppm
(ArOH)). The peculiar chemical reactivity of these com-
pounds, and notably their strong hydride and reducing
character, confirms the existence of this intramolecular
coordination [23–28]. The dihydrosilane Ph(ArO)SiH2,
for example, reacted particularly rapidly with alcohols
and acids to yield the corresponding silicon alkoxides
(or aryloxides) and esters; it was also a powerful reduc-
ing agent for aldehyde and ketones [29].
higher field than that of its tetracoordinated analogs
(PhO)2SiH2 (l = −30.47 ppm); furthermore, the JSiꢀH
1
coupling constant (1JSiꢀH=302 Hz) is significantly in-
creased compared with that observed for (PhO)2SiH2
(1JSiꢀH=238 Hz). The important displacement of the
29Si chemical shift at higher field for 9, compared with
its respective tetracoordinated compound (Dl=
39.4 ppm), express a larger electronic density around
silicon in 9 than in (PhO)2SiH2, and, therefore, is
presumably characteristic of a formal hexacoordination
1
of the silicon atom. In H-NMR the equivalence of the
four o-NMe2 groups at room temperature, as well as
the corresponding N-methylene protons, should result
from a dynamic coordination–decoordination process,
the o-NMe2 groups displacing each other rapidly on the
1H-NMR time scale. Furthermore, comparison of the
29Si–1H coupling constant of 9 with that of the
analogous tetracoordinate compound (PhO)2SiH2 re-
veals a D1JSiꢀH=64 Hz characteristic of a bicapped
tetrahedral complex. Effectively, it has been shown
previously that increasing the coordination number of
silicon with rehybridization at silicon is associated with
a decrease of the coupling constant; in contrast, an
increase of the coordination not associated with rehy-
bridization in bicapped tetrahedral complexes resulted
in an increase in the coupling constant (1JSiꢀH is depen-
dent on the s-character of the SiꢀH bond) [3a,15,30].
Additional evidence for the hypercoordination [4+2]
at silicon in 9 was obtained from the 15N-NMR spec-
trum: the 15N-NMR chemical shift for the Northo nitro-
gen atoms of the aryloxy group (l = −348.4 ppm) is
downfield of the corresponding signal for the ArOH
alcohol (l= −351.5 ppm). The idea of the ‘flip-flop’
coordination in solution (two o-NMe2 groups displac-
2.2.3.2. Dihydrosilane 9. In this case also, 29Si-NMR,
which allows the direct observation of the effect of the
electronic environment of the silicon nucleus, is the
most useful spectroscopic tool for study of coordina-
tion of the silicon atom. The 29Si-NMR spectrum of the
dihydrosilane 9 exhibits a triplet (l = −69.87 ppm) at
1
ing two others rapidly on the H-NMR time scale) via
a hexacoordinate intermediate is lent support by the
Table 7
Selected (29Si-, 1H- and 15N-) NMR data for hydrosilanes 7–10
Compounds
l
29Si (CDCl3, ppm)
Dl (ppm) 1H-NMR (CDCl3) (l, ppm)
15N-NMR (CDCl3)
(l, ppm)
o-NMe2 p-NMe2 p-CH2N o-CH2N o-NMe2 p-NMe2
ArOH
2.16
1.95
2.12
2.20
3.25
3.30
3.48
3.38
−351.5
−350.2
−347.0
−347.7
(8)
PhSiH(OAr)2
PhSiH(OPh)2
−46.71, 1JSiH=288 Hz 10.65
−36.46, 1JSiH=258 Hz
(7)
(9)
PhSiH2(OAr)
PhSiH2(OPh)
−29.69, 1JSiH=236 Hz
−20.48, JSiH =222 Hz
9.21
2.08
2.17
2.19
2.10
3.32
3.31
3.37
3.48
−348.5
−348.4
−347.53
−347.4
1
(ArO)2SiH2
(PhO)2SiH2
−69.87, 1JSiH=302 Hz 39.4
−30.47, 1JSiH=238 Hz
(2,6-R2C6H3-O)2SiH2 −37.3 (R=iPr); −37.0
(R=tBu)
(10)
(ArO)3SiH
(PhO)3SiH
−102.04, 1JSiH=358 Hz 30.58
−71.46, 1JSiH=321 Hz
2.15
2.02
3.26
3.28

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
103
The hydrosilanes behave as good reduction agents and
are also potential precursors of silyliums, silanethiones
and transition-metal-silylene complexes; trisilane could
be a source of silylene. The peculiar chemical properties
of the dihydrosilanes Ph(ArO)SiH2 and (ArO)2SiH2 and
of the silane (Me3Si)2Si(OAr)2 will be reported in future
publications.
3. Experimental section
Fig. 3. Solid-state structure of (ArO)2SiH2 (9).
3.1. General procedures
Table 8
Cl2Si(NEt2)2 [32] and H2Si(NEt2)2 [33] were prepared
as described in the appropriate references; (Me3Si)3-
SiNR2 and (Me3Si)2Si(NR2)2 [34] were obtained by
reactions of the corresponding halosilanes (Me3Si)2-
SiCl2 and (Me3Si)3SiCl [35] with the lithium derivatives
of the amines R2NH.
,
Selected bond lengths (A) and angles (°) for 9
Bond distances
Si(1)ꢀH(1)
Si(1)ꢀH(2)
Si(1)ꢀO(1)
Si(1)ꢀO(2)
Si(1)ꢀN(1)
Si(1)ꢀN(4)
1.569
1.560
1.668(3)
1.654(3)
2.986
All the compounds described are sensitive to oxygen
and moisture. All manipulations were performed under
an inert atmosphere of nitrogen or argon using stan-
dard Schlenk and high-vacuum-line techniques. Dry,
oxygen-free solvents were employed throughout. All
solvents were distilled from sodium benzophenone be-
2.630
Bond angles
H(1)ꢀSi(1)ꢀH(2)
O(2)ꢀSi(1)ꢀO(1)
O(1)ꢀSi(1)ꢀH(1)
O(2)ꢀSi(1)ꢀH(2)
O(1)ꢀSi(1)ꢀH(2)
O(2)ꢀSi(1)ꢀH(2)
126.7
101.21(17)
105.5
108.2
126.7
1
fore use. H-NMR spectra were recorded on a Bruker
AC 80 spectrometer operating at 80 MHz (chemical
shifts are reported in parts per million relative to inter-
nal Me4Si as reference) and 13C spectra on an AC 200
spectrometer; the multiplicity of the 13C-NMR signals
108.4
single crystal X-ray diffraction study performed on 9.
Translucent crystals were grown from a pentane solu-
tion cooled at −20 °C. Fig. 3 shows the solid-state
structure of 9; the relevant bond lengths and angles are
given in Table 8. The solid-state structure reveals a
hexacoordinate silicon center in an approximately C2
symmetrical molecule. The dimethylamino groups di-
rected towards the silicon center are located trans to the
oxygen centers forming N···Si···O angles of 81.79 and
1
was determined by the APT technique. H-decoupled
29Si-NMR spectra were recorded on a Bruker ARX 400
(chemical shifts are reported in parts per million rela-
tive to external Me4Si as reference). 15N spectra were
recorded on a Bruker ARX 400 spectrometer (chemical
shifts are reported in parts per million relative to exter-
nal nitromethane as reference). 7Li spectra were
recorded on a Bruker AC 200 spectrometer (chemical
shifts are reported in parts per million relative to exter-
nal LiCl/D2O as reference). Mass spectra under elec-
tron impact (EI) or chemical ionization (CH4)
conditions at 70 and 30 eV were obtained on Hewlett-
Packard 5989 and Nermag R10-10H spectrometers. IR
and UV spectra were recorded on Perkin–Elmer 1600
FT-IR and Lambda-17 spectrophotometers. Melting
points were taken uncorrected on a Leitz Biomed hot-
plate microscope apparatus. Elemental analyses (C, H,
N) were performed at the microanalysis Laboratory of
the Ecole Nationale Superieure de Chimie de Toulouse.
,
75.34°. The Si···N distances of 2.98 and 2.68 A are
significantly shorter than the sum of the van der Waals
radii (3.5 A) [31] and thus are in the range of Si···N
,
distances of hexacoordinate silicon compounds [15,30].
Actually, the geometry around the silicon atom, with
angles of 126.7° (H1ꢀSiꢀH2), 105.5° (O1ꢀSiꢀH1), 126.7°
(O1ꢀSiꢀH2) and 101.21° (O2ꢀSiꢀO1), is best described as
that of a distorted tetrahedron than that of an octahe-
dron. Two faces of the tetrahedron are ‘capped’ by two
ortho dimethylamino groups; both coordinating nitro-
gen atoms belong to different ligands and are in a cis
configuration. It is worth underlining the fact that only
three hexacoordinate bis(NꢀSi) chelates with two SiꢀO
bonds have previously been described; they have a
near-octahedral arrangement around silicon, with rela-
3.2. [2,4,6-Tris((dimethylamino)methyl)phenoxy]lithium
trimer (ArOLi )3
nBuLi (0.04 mmol, 25 ml of a solution in hexane) was
added to [2,4,6-tris((dimethylamino)methyl)phenol
(10.6 g, 0.04 mmol) in dry diethyl ether (100 ml). The
,
tively short Si···N distances (ca. 2 A) [3].
The chemistry of these 2,4,6-tris((dimethylamino)-
methyl)phenoxysilicon compounds has been explored.

104
A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
solution was cooled to 0 °C for 30 min. The mixture
was stirred for a further 2 h at room temperature and
the solvent was removed in vacuo. The residue was
extracted with a 1/1 ether/pentane solution (80 ml);
after cooling to −20 °C for 12 h, (ArOLi)3 was filtered
off as white crystals and dried in vacuo (9.8 g, 90%).
(ArOLi)3: m.p. 168–170 °C. 7Li-NMR (C6D6): 0.78.
1H-NMR (C6D6): 1.92 (s, 36H), 2.23 (s, 18H), 3.33 (s,
12H), 3.42 (s, 6H), 7.14 (s, 6H). 13C-NMR (C6D6):
45.38, 45.92, 63.90, 65.03, 121.38, 126.42, 131.53,
for C30H52Cl2N6O2Si: C, 57.44; H, 8.29; N, 13.39.
Found: C, 57.58; H, 7.97; N, 13.27%.
(2) A mixture of tetrachlorosilane (0.2 g, 1.2 mmol)
and
[2,4,6-tris((dimethylamino)methylphenoxy]tri-
methylsilane (0.81 g, 2.4 mmol) was heated, at 80 °C, in
a sealed tube overnight. The wet solid obtained was
washed with pentane (20 ml) and dried in vacuo to give
2 (0.6 g, 80%).
A
solution of 2,4,6-tris((dimethylamino)methyl)-
phenol (2.84 g, 10.7 mmol) in 100 ml of dry toluene was
slowly added to a solution of bis(diethylamino)-
dichlorosilane [32] (1.3 g, 5.37 mmol) in 50 ml of dry
toluene heated at 110 °C. Slow distillation (6 h) of the
solvent and of the diethylamine formed led to a white
solid, which was washed with 30 ml of dry pentane and
dried in vacuo to afford crude 2 (1.07 g, 23%). The
analysis by mass spectroscopy (EI, 70 eV) showed trace
amounts of two other species, m/z=663 [(ArO)2Si-
167.12. MS: m/z=813 [M]+
.
Anal. Calc. for
’
C45H78Li3N9O3: C, 66.42; H, 9.59; N, 15.49. Found: C,
66.22; H, 9.54; N, 15.44%.
3.3. Trichloro[2,4,6-((dimethylamino)methyl)phenoxy]-
silane Cl3SiOAr (1)
(1) A solution of [2,4,6-tris((dimethylamino)methyl)-
phenoxy]lithium (1.12 g, 4.13 mmol) in 20 ml of ether
was added dropwise to a stirred solution (cooled at
0 °C) of tetrachlorosilane (0.7 g, 4.13 mmol) in 50 ml of
ether. The mixture was stirred at room temperature for
2 days. Filtration, followed by drying in vacuo, af-
forded crude 1 (0.6 g, 25%). 1: m.p. 180–182 °C. 29Si-
(Cl)NEt2]+ and m/z=892 [(ArO)3SiNEt2]+ , besides
2.
’
’
3.5. [2,4,6-Tris((dimethylamino)methyl)phenoxy]-
trimethylsilane Me3SiOAr (3)
(1) To a solution of chlorotrimethylsilane (0.77 g,
7.08 mmol) in 15 ml of ether was slowly added a solu-
tion of [2,4,6-tris((dimethylamino)methyl)phenoxy]-
lithium (1.92 g, 7.08 mmol) in 25 ml of ether. The reac-
tion mixture was stirred at room temperature for
2 days. Filtration of LiCl and (ArO)2Li3Cl, followed by
concentration under vacuum, afforded 3 (0.71 g, 30%).
3: b.p. 113–114 °C/6×10−2 mmHg. 29Si-NMR
(CDCl3): 18.19. 15N-NMR (CDCl3): −347.5, −350.1.
1H-NMR (C6D6): 0.24 (s, 9H), 2.11 (s, 12H), 2.13 (s,
6H), 3.30 (s, 2H), 3.38 (s, 4H), 7.4 (s, 2H). 13C-NMR
(C6D6): 1.08, 45.37, 45.63, 59.61, 64.26, 129.78, 130.69,
1
NMR (CD2Cl2): −30.80. H-NMR (CD2Cl2): 2.16 (s,
6H), 2.18 (s, 12H), 3.35 (s, 2H), 3.57 (s, 4H), 7.22 (s,
2H). 13C-NMR (CD2Cl2): 43.10, 45.83, 58.32, 61.76,
119.91, 123.80, 126.96, 152.33. MS: m/z=398 [M−
H]+. Anal. Calc. for C15H26Cl3N3OSi: C, 45.20; H,
6.52; N, 10.53. Found: C, 45.38; H, 6.34; N, 10.42%.
(2) A mixture of Me3SiOAr (0.5 g, 1.48 mmol) and
tetrachlorosilane (0.25 g, 1.48 mmol) was heated at
80 °C, in a sealed tube, overnight. Addition of 20 ml of
pentane, filtration and drying in vacuo gave 1 as a
white solid (0.48 g, 82%).
132.45, 152.18. MS: m/z=337 [M]+ . Anal. Calc. for
’
3.4. Bis[2,4,6-tris((dimethylamino)methyl)phenoxy]-
dichlorosilane Cl2Si(OAr)2 (2)
C18H35N3OSi: C, 64.09; H, 10.38; N, 12.46. Found: C,
64.41; H, 10.42; N, 12.65%.
(2) A solution of 2,4,6-tris((dimethylamino)methyl)-
phenol (2.5 g, 9.43 mmol) in 30 ml of pentane was
slowly added to a stirred solution of (dimethylamino)-
trimethylsilane (1.1 g, 9.43 mmol) in 20 ml of pentane.
Concentration and distillation gave 3 (3 g, 94%).
(1) A solution of [2,4,6-tris((dimethylamino)methyl)-
phenoxy]lithium (1.52 g, 5.68 mmol) in 30 ml of ether
was added dropwise to a stirred solution at 0 °C of
tetrachlorosilane (0.47 g, 2.8 mmol) in 25 ml of ether.
The mixture was stirred at room temperature for
2 days. After elimination of LiCl and (ArO)2Li3Cl by
filtration, the filtrate was concentrated in vacuo to give
crude 2 as a white solid (0.4 g, 23%). 2: m.p. 150–
190 °C (dec.). 29Si-NMR (CD2Cl2): −42.40; at −60 °C
3.6. Bis[2,4,6-tris((dimethylamino)methyl)phenoxy]-
dimethylsilane Me2Si(OAr)2 (4)
(1) To a suspension of [2,4,6-tris((dimethylamino)-
methyl)phenoxy]lithium (2.12 g, 7.82 mmol) in 25 ml of
1
(CD2Cl2): −51.42. H-NMR at 25 °C (CD2Cl2): 2.13
(broad singlet (s*), 12H), 2.16 (s*, 24H), 3.32 (s*, 4H),
3.54 (s*, 8H), 7.69 (s, 4H); at −60 °C (CD2Cl2): 2.11
(s*, 12H), 2.12 (s*, 12 H), 2.21 (s*, 12H), 3.30 (s*, 4H),
3.48 (s*, 4H), 3.53 (s*, 4H), 7.71 (s, 4H). 13C-NMR
(CD2Cl2): 43.70, 44.08, 58.81, 62.05, 120.09, 124.86,
132.96, 158.18. MS: m/z=590 [M−HCl]+. Anal. Calc.
ether was slowly added a solution of dichloro-
dimethylsilane (0.5 g, 3.91 mmol) in 15 ml of ether. The
reaction mixture was stirred at room temperature for
2 days. Filtration, concentration and distillation in
vacuo yielded 4 (0.64 g, 28%). 4: b.p. 180–182 °C/
0.1 mmHg. 29Si-NMR (CDCl3): −3.02. 1H-NMR

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
105
61.53; H, 9.96; N, 11.95. Found: C, 61.75; H, 10.04; N,
11.81%.
(CDCl3): 0.19 (s, 6H), 2.15 (s, 12H), 2.16 (s, 24 H), 3.32
(s, 4H), 3.50 (s, 8H), 7.02 (s, 4H). 13C-NMR (CDCl3):
14.16, 45.40, 45.64, 59.05, 63.98, 129.43, 130.50, 131.86,
151.35. MS: m/z=586 [M]+
.
Anal. Calc. for
’
3.9. [2,4,6-Tris((dimethylamino)methyl)phenoxy]phenyl-
and bis[2,4,6-tris((dimethylamino)methyl)phenoxy]-
phenyl-silane Ph(ArO)SiH2 (7) and Ph(ArO)2SiH (8)
C32H58N6O2Si: C, 65.55; H, 9.89; N, 14.32. Found: C,
65.83; H, 10.29; N, 14.11%.
(2)
methyl)phenol (2 g, 7.54 mmol) in 30 ml of pentane was
added dropwise to solution of bis(diethy-
lamino)dimethylsilane (0.55 g, 3.77 mmol) in 30 ml of
pentane. The reaction mixture was stirred and heated to
reflux for 2 hours. After returning to room temperature,
the solution was concentrated in vacuo and the residue
was distilled in vacuo to give 4 (2 g, 91%).
A
solution of 2,4,6-tris((dimethylamino)-
To a solution of trifluoromethanesulfonate of phenyl-
silane [35] (8 g, 31.25 mmol) in 80 ml of toluene at
−30 °C was added dropwise a mixture of 2,4,6-tris-
((dimethylamino)methyl)phenol (8.28 g, 31.25 mmol)
and triethylamine (3.15 g, 31.25 mmol). The reaction
mixture was stirred at room temperature for 3 h. After
decanting and elimination by siphoning of the
Et3N·TfOH formed, the residual solution was concen-
trated and distilled under vacuum to give 7 (6.9 g, 60%)
and 8 (3.96 g). 7: b.p. 108–110 °C/5×10−2 mmHg.
a
3.7. [2,4,6-Tris((dimethylamino)methyl)phenoxy]-
tris(trimethylsilyl)silane (Me3Si )3SiOAr (5)
1
29Si-NMR (CDCl3): −29.69 (t, JSiꢀH=236 Hz). 15N-
1
NMR (CDCl3): −347.53, −348.5. H-NMR (CDCl3):
(1) To a solution of tris(trimethylsilyl)chlorosilane
[36] (0.48 g, 1.69 mmol) in 15 ml of ether was added a
suspension of [2,4,6-tris((dimethylamino)methyl)phe-
noxy]lithium (0.46 g, 1.69 mmol) in 20 ml of ether. The
mixture was stirred at room temperature for 2 days.
Filtration and concentration in vacuo afforded pure 5
(0.2 g, 23%). 5: 29Si-NMR (CDCl3): −15.9, −2.8.
1H-NMR (CDCl3): 0.23 (s, 27H), 2.08 (s, 6H), 2.19 (s,
12H), 3.35 (s, 2H), 3.36 (s, 4H), 7.12 (s, 2H). 13C-NMR
(CDCl3): −0.25, 45.01, 45.42, 58.1, 63.70, 128.82,
2.08 (s, 6H), 2.19 (s, 12H), 3.32 (s, 2H), 3.37 (s, 4H),
5.12 (s, 2H), 7.05 (s, 2H), 7.10–7.40 (m, 5H). 13C-NMR
(C6D6): 45.38, 59.85, 64.25, 122.06, 129.39, 130.54,
132.65, 132.99, 134.42, 137.15, 151.82. IR (CDCl3, KBr,
cm−1): wSiꢀH=2157. MS: m/z=370 [M−1]+. 8: b.p.
180–182 °C/5×10−2 mmHg. 29Si-NMR (CDCl3):
−46.71 (d, 1JSiꢀH=288 Hz). 15N-NMR (CDCl3):
1
−347.7, −350.2. H-NMR (CDCl3): 1.95 (s, 12H), 2.2
(s, 24H), 3.3 (s, 4H), 3.38 (s, 8H), 5.25 (s, 1H), 7.05 (s,
4H), 7.1–7.4 (m, 5H). 13C-NMR (CDCl3): 45, 45.31,
59.21, 63.88, 127.38, 127.57, 128.54, 130.04, 131.2,
132.16, 136.6, 151.42. IR (CDCl3, KBr, cm−1):
129.58, 129.89, 152.22. MS: m/z=511 [M]+ ; 438
’
[M−Me3Si]+. Anal. Calc. for C24H53N3OSi4: C, 56.38;
H, 10.36; N, 8.21. Found: C, 56.04; H, 10.52; N, 8.46%.
(2) To a solution of (dimethylamino)tris(trimethyl-
silyl)silane (1.0 g, 3.77 mmol) in 15 ml of pentane was
slowly added a solution of 2,4,6-tris((dimethylamino)-
methyl)phenol (1.09 g, 3.77 mmol) in 15 ml of pentane.
The reaction mixture was refluxed for 2 h. After return-
ing to room temperature, the volatiles were removed in
vacuo to give 5 (1.6 g, 83%).
wSiꢀH=2205. MS: m/z=634 [M]+
.
’
3.10. Bis[2,4,6-tris((dimethylamino)methyl)phenoxy]-
dihydrosilane (ArO)2SiH2 (9)
A
solution of 2,4,6-tris((dimethylamino)methyl)-
phenol (6.12 g, 23.1 mmol) in 20 ml of chloroform was
slowly added to a stirred solution of bis(diethy-
lamino)dihydrosilane in 10 ml of chloroform. The reac-
tion mixture was stirred at room temperature for
15 min. The volatiles were removed under reduced pres-
sure. Crystallization from pentane (30 ml) at −20 °C
afforded 9 (6.2 g, 96%) as white crystals. 9: 29Si-NMR
(CDCl3): −69.87 (t, 1JSiꢀH=302 Hz). 1H-NMR
(CDCl3): 2.10 (s, 12H), 2.17 (s, 24H), 3.31 (s, 4H), 3.48
(s, 8H), 4.36 (s, 2H), 7 (s, 4H). 15N-NMR (CDCl3):
−348.4, −347.4. 13C-NMR (CDCl3): 45.26, 45.43,
59.16, 60.02, 127.73, 129.95, 130.61, 152.49. IR (CDCl3,
KBr, cm−1): wSiꢀH=2195. MS: m/z=557 [M−1]+.
3.8. Bis[2,4,6-tris((dimethylamino)methyl)phenoxy]-
bis(trimethylsilyl)silane (ArO)2Si(SiMe3)2 (6)
To a stirred solution of bis(dimethylamino)bis-
(trimethylsilyl)silane (1.3 g, 4.96 mmol) in 20 ml of tolu-
ene was slowly added a solution of 2,4,6-tris((dimethy-
lamino)methyl)phenol (2.63 g, 9.93 mmol) in 30 ml of
toluene. The reaction mixture was refluxed for 2 h. The
volatiles were removed in vacuo. Addition of 30 ml of
pentane and crystallization at −20 °C gave 6 (3.3 g,
95%) as white crystals. 6: m.p. 70–72 °C. 29Si-NMR
(CDCl3): −20.5, 8.0. 1H-NMR (CDCl3): −0.01 (s,
18H), 2.18 (s, 12H), 2.20 (s, 24H), 3.37 (s, 4H), 3.56 (s,
8H), 7.22 (s, 4H). 13C-NMR (CDCl3): −0.27, 45.20,
45.55, 58.44, 63.92, 128.94, 129.61, 129.66, 152.32. MS:
3.11. Tris[2,4,6-tris((dimethylamino)methyl)phenoxy]-
hydrosilane (ArO)3SiH (10)
A mixture of tris(dimethylamino)hydrosilane (1.7 g,
6.94 mmol) and 2,4,6-tris((dimethylamino)methyl)-
m/z=702 [M]+ . Anal. Calc. for C36H70N6O2Si3: C,
’

106
A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
phenol (5.52 g, 20.83 mmol) was heated in a sealed tube
at 110 °C for 2 days in the presence of ammonium
sulfate (catalytic amount). The crude reaction product
was washed with 20 ml of pentane. Filtration and con-
centration in vacuo gave 10 (5.24 g, 92%). 10:
4. Supplementary material
Crystallographic data (excluding structure factors)
have been deposited with the Cambridge Crystallo-
graphic Data Center, CCDC 158701–158703. Copies of
the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambrige CB2 1EZ, UK
(fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
1
1
29Si-NMR (CDCl3): −102.04 (d, JSiꢀH=358 Hz). H-
NMR (CDCl3): 2.02 (s, 18H), 2.15 (s, 36H), 3.26 (s,
6H), 3.28 (s, 12H), 5.11 (s, 1H), 7.03 (s, 6H). 13C-NMR
(CDCl3): 45.32, 45.50, 58.10, 59.02, 128.21, 130.35,
132.70, 151.29. IR (CDCl3, KBr, cm−1): wSiꢀH=2243.
MS: m/z=821 [M]+
.
’
References
3.12. X-ray crystallographic studies of compounds 3, 6
and 9
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Crystal data for all structures are presented in Table
9. Data were collected at low temperatures on a Stoe-
,
IPDS diffractometer with Mo–Ka (u=0.71 073 A). The
structures were solved by direct methods by means of
SHELXS-97 [37] and refined with all data on F2 by
means of SHELXL-97 [38]. All non-hydrogen atoms were
refined anisotropically. The hydrogen atoms of the
molecules were geometrically idealized and refined us-
ing a riding model. The disorder of a dimethylamino
group in 6 was refined on two positions with the help of
50 ADP and distance restraints.
Table 9
Summary of crystal data and structure refinement for (ArOLi)3,
(Me3Si)2(OAr)2 (6) and (ArO)2SiH2 (9)
(ArOLi)3
6
9
Formula
MT
T (K)
Crystal
system
C45H78Li3N9O3 (C18H35N3OSi)1.5 C30H54N6O2Si
813.98
173(2)
351.63
173(2)
558.88
173(2)
[3] (a) D. Kost, I. Kalikhman, M. Raban, J. Am. Chem. Soc. 117
(1995) 11 512;
Monoclinic
Monoclinic
Triclinic
(b) I. Kalikhman, D. Kost, J. Chem. Soc. Chem. Commun.
(1995) 1253;
(c) I. Kalikhman, S. Krivonos, D. Stalke, T. Kottke, D. Kost,
Organometallics 16 (1997) 3255;
(d) D. Kost, I. Kalikhman, S. Krivonos, D. Stalke, T. Kottke, J.
Am. Chem. Soc. 120 (1998) 4209.
(
Space group P21/c
Ia
P1
,
a (A)
20.836(4)
20.613
8.798(2)
90
97.26(2)
90
5021(2)
4
1.077
19.087(2)
11.465(2)
19.734(2)
90
94.930(10)
90
4302.5(10)
8
1.086
9.426(2)
11.740(3)
16.245(3)
70.54(2)
76.66(2)
84.83(3)
1649.1(16)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
Z
zcalcd
[4] (a) J. Barrau, G. Rima, T. El Amraoui, Organometallics 17
(1998) 607;
3
(b) J. Barrau, G. Rima, T. El Amraoui, J. Organomet. Chem.
570 (1998) 163;
(c) J. Barrau, G. Rima, T. El Amraoui, J. Organomet. Chem.
561 (1998) 167.
,
1.126
(Mg m−3
)
[5] D. Seebach, Angew. Chem. 100 (1988) 1685 and references cited
therein.
Crystal size 0.6×0.5×0.1
0.6×0.5×0.1
0.6×0.4×0.1
(mm3)
v (mm−1
)
0.067
R (I\2|(I)) 0.397
0.146
0.0364
0.0961
0.106
0.0606
0.1521
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Chem. 32 (1993) 4111.
a
wR2 (all
0.0784
data)
a wR2=[S w(Fo2−Fc2)2/S w(Fo2)2]1/2
.

A. Akkari-El Ahdab et al. / Journal of Organometallic Chemistry 636 (2001) 96–107
107
[9] [(ArO)2SiH]+ −
I
was identified by comparison of the spectral
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data with those of an authentic sample. Improved detailed
procedures for its synthesis will be reported in a publication
currently in preparation. M.p. 204–205 °C (dec.). 29Si-NMR
(CDCl3): −106.28 (d, 1JSiH=347 Hz). 15N-NMR (CDCl3):
−335.1, −343.9, −350. 1H-NMR (CDCl3): 2.12 (s, 12H), 2.39
(s, 12H), 2.67 (s, 6H), 2.86 (s, 6H), 3.37 (s, 4H), 3.68 (s, 4H),
lA=4.19 (2H) and lB=4.48 (2H) 2JAB=13.2 Hz, 7.31 (s, 4H).
13C-NMR (CDCl3): 43.93, 44.73, 45.37, 59.22, 59.84, 62.29,
120.02, 127.99, 130.86, 149.99. IR (KBr, CDCl3, cm−1): wSiꢀH
2212. MS: FAB (MNBA)\0, m/z=557 [(ArO)2SiH]+, FAB
B0, m/z=127 [I]−
=
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18H), 2.54 (s, 12H). 13C-NMR (CDCl3): 0.33, 39.92. MS: m/z=
262 [M]+
.
’
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