Synthesis, structures and reactions of lithium complexes of [(o-RCHC 6H4)PPh2=NSiMe3]- (R = H, SiMe3) ligands

Article abstract of DOI:10.1039/b418389d

N-Trimethylsilyl o-methylphenyldiphenylphosphinimine, (o-MeC ₆H₄)PPh₂=NSiMe₃ (1), was prepared by reaction of Ph₂P(Br)=NSiMe₃ with o-methylphenyllithium. Treatment of 1 with LiBuⁿ

Full text of DOI:10.1039/b418389d

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F U L L P A P E R
Synthesis, structures and reactions of lithium complexes of
−
=
[(o-RCHC6H4)PPh2 NSiMe3] (R = H, SiMe3) ligands
Zhong-Xia Wang* and Chun-Yan Qi
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026,
P. R. China. E-mail: zxwang@ustc.edu.cn; Fax: +86 551 3601592; Tel: +86 551 3603043
Received 7th December 2004, Accepted 13th January 2005
First published as an Advance Article on the web 3rd February 2005
=
N-Trimethylsilyl o-methylphenyldiphenylphosphinimine, (o-MeC6H4)PPh2 NSiMe3 (1), was prepared by reaction of
n
=
Ph2P(Br) NSiMe3 with o-methylphenyllithium. Treatment of 1 with LiBu and then Me3SiCl afforded (o-Me3SiCH2-
n
=
C6H4)PPh2 NSiMe3 (2). Lithiations of both 1 and 2 with LiBu in the presence of tmen gave crystalline lithium
=
complexes [Li{CH(R)C6H4(PPh2 NSiMe3)-2}·tmen] (3, R = H; 4, R = SiMe3). From the mother liquor of 4, traces
=
of the tmen-bridged complex [Li{CH(SiMe3)C6H4(PPh2 NSiMe3)-2}]2(l-tmen) (5) were obtained. Reaction of 2
n
=
with LiBu in Et2O yielded complex [Li{CH(SiMe3)C6H4(PPh2 NSiMe3)-2}·OEt2] (6). Reaction of lithiated 1 with
=
Me2SiCl2 in a 2:1 molar ratio afforded dimethylsilyl-bridged compound Me2Si[CH2C6H4(PPh2 NSiMe3)-2]2 (7).
n
=
Lithiation of 7 with two equivalents of LiBu in Et2O yielded [Li2{(CHC6H4(PPh2 NSiMe3)-2)2SiMe2}·0.5OEt2]
=
(8·0.5OEt2). Treatment of 4 with PhCN formed a lithium enamide complex [Li{N(SiMe3)C(Ph)CHC6H4(PPh2
NSiMe3)-2}·tmen] (9). Reaction of two equivalents of 5 with 1,4-dicyanobenzene gave a dilithium complex
=
[{Li(OEt2)2}2(1,4-{C(N(SiMe3)CHC6H4(PPh2 NSiMe3)-2}2C6H4)] (10). All compounds were characterised by
NMR spectroscopy and elemental analyses. The structures of compounds 2, 3, 5, 6 and 9 have been determined by
single crystal X-ray diffraction techniques.
Introduction
Ligands bearing a sidearm donor are widely used in coordina-
tion and organometallic chemistry.1,2 The ligands provide extra
stabilisation and structural rigidity and often lead to remarkable
reactivity due to intramolecular chelating coordination.3 The
donation functionality has also a strong influence on the reaction
selectivity or catalytic activity of the complexes.4 For example,
Kol and coworkers found that the catalytic activity for olefin
polymerisation of amine bis(phenolate) complexes of zirconium
and hafnium was strongly influenced by an extra donor on a
sidearm of the ligand.4,5 A number of organolithium complexes
with chelated structures via a sidearm donation have been
reported. They were used as ligand transfer reagents and also
showed interesting structural features. For example, reactions6
=
of [LiC6H4(Ph2P NSiMe3)-2] with halides of Zn, Cu(I), In(III),
Fe(II), Sn(II), and Pb(II) or with Ph3GeCl gave the corresponding
aryl complexes.7 Recently, solution structures and dynamics
of amine- and ether-chelated aryllithium complexes were sys-
tematically studied. The effects of the chelate ring size and
chelating atom on the structural, stereochemical and chemical
properties of the lithium complexes were explored.8 Herein we
report the synthesis, structures and reactions of lithium com-
=
plexes of C,N-chelating ligands with a Ph2P NSiMe3 sidearm,
=
[Li·L{CH(R)C6H4(PPh2 NSiMe3)-2}] (R = H or SiMe3; L =
Et2O or tmen).
Results and discussion
=
The synthesis and reactions of (o-RCH2C6H4)PPh2 NSiMe3
(R = H, SiMe3) are summarised in Scheme 1.
Scheme 1
N-Trimethylsilyl-o-methylphenyldiphenylphosphinimine, (o-
MeC6H4)PPh2 NSiMe3 (1), was prepared by the reaction of
=
by single crystal X-ray diffraction as 5. In the molecule two
=
=
Ph2P(Br) NSiMe3 with o-methylphenyllithium in high yield.
[Li{CH(SiMe3)C6H4(PPh2 NSiMe3)-2}] units were joined by a
Treatment of 1 with LiBun in Et2O and subsequent Me3SiCl
tmen bridge. tmen generally functions as a chelating bidentate
ligand. This bridging coordination mode is relatively rare.9
Compounds 1 and 2 were also lithiated by treatment with LiBun
in Et2O, but only the lithiated product of 2 was isolated as
yellow–orange crystals (6). Complex 6 can be converted to 4
by its recrystallisation with tmen in hexane. Treatment of 1 with
LiBun in Et2O and then half equivalents of Me2SiCl2 afforded
=
gave (o-Me3SiCH2C6H4)PPh2 NSiMe3 (2). Attempts to prepare
compounds 1 and 2 by reaction of (o-RCH2C6H4)PPh2 (R =
H, SiMe3) with Me3SiN3 were unsuccessful. Both 1 and 2
reacted readily with LiBun in the presence of tmen to afford
lithium complexes 3 and 4, respectively. From the mother
liquor of 4, a few crystals were further obtained and identified
9 9 6
D a l t o n T r a n s . , 2 0 0 5 , 9 9 6 – 1 0 0 1
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
©

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=
Me2Si[CH2C6H4(PPh2 NSiMe3)-2]2 (7) as colourless crystals
(Scheme 2). Reaction of compound 7 with two equivalents
of LiBun in Et2O gave a dilithium complex, assumed to be
8·0.5Et2O, as red crystals. Reaction of complex 4 with PhCN
in Et2O proceeded readily and formed red crystalline complex 9
(Scheme 3). A 1,3-trimethylsilyl C → N migration was observed
in the reaction. Similar treatment of two equivalents of 6 with
1,4-dicyanobenzene in hexane afforded dilithium complex 10
in high yield. If the reaction was carried out in Et2O or thf, a
mixture was obtained.
Fig. 1 Molecular structure of 2 shown with 30% thermal ellipsoids.
◦
˚
Selected bond lengths (in A) and angles (in ): P1–N1, 1.539(3); P1–C1,
1.828(3); P1–C7, 1.816(3); P1–C13, 1.822(4); N1–P1–C1, 117.16(15);
N1–P1–C7, 111.87(16); C7–P1–C1, 104.86(15).
and angles. Crystalline 2 is monomeric. The P atom is four-
coordinate, having a distorted tetrahedral geometry. The P–N
˚
bond length of 1.539(3) A is indicative of a P–N double bond,
˚
whereas the P–C distances of 1.816(3)–1.828(3) A show these to
be P–C single bonds.10
Complex 3 is a monomer and crystallises with two molecules
in the unit cell. An ORTEP representation of the structure
of a single molecule is shown in Fig. 2 along with selected
bond lengths and angles. The lithium atom lies outside C7–
C2–C1 plane. The torsion angle of Li1C7C2C1 is 58.1◦. The
Scheme 2
˚
Li1–C7 distance of 2.300(10) A is a little longer than those
11
˚
=
in [Li{CH(SiMe3)PPh2 NSiMe3}]2 (average 2.156 A), but
=
shorter than those in [Li{CH(PPh2 NSiMe3)2}]2 [2.370(9)–
12
13
˚
˚
=
2.784(10) A] and [Li2{C(PPh2 NSiMe3)2}]2 (average 2.38 A).
˚
The distance of the Li1 · · · C2 contact [2.694(10) A] is too
long to be considered as contributing significantly to the
˚
=
bonding. The 2.103(9) A of Li1–N1 distance is longer than
6
˚
those in [LiC6H4(Ph2P NSiMe3)-2] (average 2.032 A) and
11
˚
=
[Li{CH(SiMe3)PPh2 NSiMe3}(OEt2)2] [2.018(5) A], but still
within the normal range as observed for lithium amides14 and
lithium phosphinimines.11,13,15
Scheme 3
The compounds 1–10 were characterised by 1H, 13C and
1
31P NMR spectroscopy and elemental analysis. The H NMR
spectrum of complex 3 showed that the two protons of CH2
group were inequivalent, the chemical shifts being at 3.07
and 3.17 ppm, respectively. In complex 8 two Me groups of
1
SiMe2 were inequivalent. However, the H, 13C and 31P NMR
=
spectra showed that the two [CHC6H4(PPh2 NSiMe3)-2] units
in complex 8 had identical chemical environments. For example,
1
Fig. 2 Molecular structure of 3 shown with 20% thermal ellipsoids.
its H NMR spectrum gave single CH signal at 2.98 ppm and
◦
˚
Selected bond lengths (in A) and angles (in ): Li1–N1, 2.103(9); Li1–C7,
2.300(10); Li1–C2, 2.694(10); Li1–N3, 2.172(9); Li1–N4, 2.165(9);
P1–N1, 1.576(4); P1–C1, 1.765(5); C2–C7, 1.376(6); N1–Li1–C7,
93.6(4); N1–Li1–N3, 127.5(4); N3–Li1–C7, 107.5(4); C2–C7–Li1,
90.6(4); P1–N1–Li1, 107.9(3); N1–P1–C1, 113.1(2).
single SiMe3 signal at 0.35 ppm, the 31P NMR spectrum also
gave single resonance signal. The 1H NMR spectrum of 10
showed that in the molecule the chemical environment of two
azaallyl units was identical.
The structures of compounds 2, 3, 5, 6 and 9 were further
characterised by single crystal X-ray diffraction. The structure
of 2 is presented in Fig. 1 along with selected bond lengths
The structure of complex 5 is presented in Fig. 3 along
with selected bond lengths and angles. The molecule lies about
D a l t o n T r a n s . , 2 0 0 5 , 9 9 6 – 1 0 0 1
9 9 7

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Fig. 3 Molecular structure of 5 shown with 30% thermal ellipsoids.
◦
˚
Selected bond lengths (in A) and angles (in ): Li1–N1, 2.022(5); Li1–N2,
2.104(6); Li1–C19, 2.203(6); Li1–C18, 2.409(5); Li1–C13, 2.636(6);
P1–N1, 1.574(2); P1–C13, 1.787(3); C18–C19, 1.421(4); N1–Li1–N2,
129.1(3); N1–Li1–C19, 97.8(2); N2–Li1–C19, 131.5(3); N1–P1–C13,
109.87(12); Li1–C19–C18, 80.2(2); P1–N1–Li1, 102.17(8).
Fig. 5 Molecular structure of 9 shown with 20% thermal ellipsoids.
◦
˚
Selected bond lengths (in A) and angles (in ): Li1–N2, 1.972(6); Li1–N3,
2.083(7); Li1–N4, 2.134(7); Li1–C3, 2.651(7); Li1–C7, 2.752(7); Li1–C8,
2.496(6); N2–C8, 1.360(4); C2–C7, 1.446(4); C7–C8, 1.381(4); P1–N1,
1.545(3); N2–Li1–N3, 131.1(3); N2–Li1–N4, 132.5(4); N3–Li1–N4,
86.2(3); N2–Li1–C8, 32.87(13); N2–Li1–C7, 59.24(18); N2–C8–C7,
125.0(3); C2–C7–C8, 130.3(3).
an inversion centre and that the additional letters “A” in the
atom labels in Fig. 3 refer to atoms at equivalent position
(2 − x, 1 − y, −z). The complex is monomeric in the
solid state. In the molecule, tmen bridges two [Li{CH(SiMe3)-
=
C6H4(PPh2 NSiMe3)-2}] units via the coordination of the
nitrogen atoms to the lithium atoms. The atoms N1, N2, Li1
and C19 are approximately coplanar, the sum of angles at lithium
atom being 358.4◦. The torsion angle of Li1C19C18C13 is 58.6◦,
very close to corresponding that in complex 3. The Li1–C19
The Li(tmen) group is positioned above N1C8C7 plane. The
˚
Li1–N2 distance of 1.972(6) A is in the normal range for the Li–
N (amide) bonds.14 The Li1–C8 distance of 2.496(6) A shows
˚
˚
distance of 2.203(6) A is slightly shorter than that in 3 [2.300(10)
significant bonding interaction, while the distances between Li1
and the C7, C2, and C3 atoms are too long for a bonding
interaction. Although the bond distances from the lithium atom
to N2, C8, C7, C2 and C3 suggest that some extent of p
interaction is present, it is probably more proper to regard 9
˚
˚
A]. The Li1–N1 distance of 2.024(7) A is also shorter than
˚
corresponding that in 3 [2.103(9) A]. In addition, it is also noted
that the distance of Li1–C18 [2.409(5) A] is apparently shorter
than Li1–C2 in 3 [2.694(10) A]. These are ascribed to lower
˚
˚
coordinate number of the lithium atoms in 5 than in 3.
3
as an enamide, rather than an g -1-azaallyl.16 The structure of 9
The structure of complex 6 is shown in Fig. 4 along with
selected bond lengths and angles. Complex 6 is also monomeric
in the solid state. The bond parameters of 6 are similar to those
is similar to those of [Li{N(SiMe3)C(Ph)C(H)Ph}(tmen)]16 and
[Li2(tmen)2{o-, m-or p-{N(SiMe3)C(R)C(H)}2C6H4}] (R = But,
Ph).17
˚
of complex 5. For example, the Li1–C19 distance of 2.216(8) A
The structure of complex 10 was also determined by single
crystal X-ray diffraction techniques. However, the data quality
is poor due to the quality of the crystal. Hence, the data is not
reported here. Even so, the coordinate mode of the complex can
be identified from the data. The structure is similar to that of 9.
˚
in 6 is close to corresponding that in 5 [2.203(6) A]. The distances
˚
˚
of Li1–N1 and Li1–C18 [2.024(7) A and 2.402(8) A, respectively]
˚
in 6 are almost identical to coresponding those in 5 [2.022(5) A
˚
and 2.409(5) A, respectively].
=
Namely, there is no interaction between Ph2P NSiMe3 groups
and the lithium atoms. The Li–N distances are short, while the
distances between the lithium atoms and the carbon atoms of
the respective azaallyl are rather long.
Experimental
All experiments were performed under nitrogen using standard
Schlenk and vacuum line techniques. Solvents were distilled
under nitrogen over sodium (toluene), sodium–benzophenone
(benzene, thf, Et2O and n-hexane) and degassed prior to use.
C6D6 were purchased from Acros Organics and stored over
Na/K alloy and degassed prior to use. CDCl3, Ph2PCl and
1,4-dicyanobenzene were purchased from Acros Organics and
used as obtained. LiBun was purchased from Acros Organics
and Alfa Acesar and used as received. tmen was purchased
from Acros Organics, dried with sodium and distilled prior
Fig. 4 Molecular structure of 6 shown with 20% thermal ellipsoids. Se-
to use. Ph2P(Br) NSiMe3 and o-MeC6H4Li19 were prepared
18
=
◦
˚
lected bond lengths (in A) and angles (in ): Li1–N1, 2.024(7); Li1–C19,
2.216(8); Li1–C18, 2.402(8); Li1–C13, 2.718(8); Li1–O1, 1.925(8);
P1–N1, 1.573(3); P1–C13, 1.788(4); C18–C19, 1.416(5); N1–Li1–C19,
102.6(3); N1–Li1–O1, 132.0(4); C19–Li1–O1, 125.3(4); C18–C19–Li1,
79.5(3); P1–N1–Li1, 102.8(2); C13–P1–N1, 109.91(16).
according to the literature. NMR spectra were recorded on a
Bruker av400 or av300 spectrometer at ambient temperature.
1
The chemical shifts of 1H and 13C{ H} NMR spectra are refer-
1
enced to internal solvent resonances; the 31P{ H} NMR spectra
are referenced to external 85% H3PO4. Elemental analyses were
performed by the Analytical Centre of University of Science
and Technology of China and the Analytical Laboratory of
Shanghai Institute of Organic Chemistry. Melting points were
uncorrected.
The ORTEP drawing of complex 9 is exhibited in Fig. 5,
along with selected bond lengths and angles. Crystalline 9 is
monomeric and there is not coordinate interaction between the
=
nitrogen atom of Ph2P NSiMe3 group and the lithium atom.
9 9 8
D a l t o n T r a n s . , 2 0 0 5 , 9 9 6 – 1 0 0 1

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Preparations
Ph + C6H4), 6.55–6.63 (m, 1H, Ph + C6H4), 6.88–6.95 (m, 2H,
Ph + C6H4), 7.10–7.20 (m, 6H, Ph + C6H4), 7.65–8.25 (b, 4H,
Ph + C6H4). 13C NMR (C6D6): d 1.90, 5.10 (d, J = 4 Hz), 46.49,
57.71, 60.21, 105.51, 123.85 (d, J = 10.8 Hz), 130.66 (d, J =
2.8 Hz), 132.30, 132.44, 133.30 (d, J = 9.7 Hz), 134.92, 137.63,
159.25. 31P NMR (C6D6): d 23.50.
The mother liquor was further concentrated to afford several
crystals identified by single crystal X-ray diffraction techniques
as complex 5.
=
(o-MeC6H4)PPh2 NSiMe3 (1). To a diethyl ether solution
=
of Ph2P(Br) NSiMe3 prepared from Ph2PN(SiMe3)2 (7.53 g,
21.79 mmol) and Br2 (1.12 cm3, 21.79 mmol) was added a diethyl
ether solution of LiC6H4Me-2 (prepared from 2-BrC6H4Me and
Li) at about −80 ◦C. The mixture was allowed to warm to room
temperature and stirred overnight. Solvent was removed and the
residue was extracted with benzene (30 cm3 × 2). The mixture
was filtered and distilled in vacuo to dry to give white solid.
The solid was recrystallised from hexane to afford colourless
crystals (4.76 g, 60%), mp 81–83 ◦C (Found: C, 72.63; H, 7.25;
N, 3.77%. C22H26NPSi requires C, 72.69; H, 7.21; N, 3.85%).
1H NMR (CDCl3): d −0.01 (s, 9H, SiMe3), 2.25 (s, 3H, Me),
7.04–7.15 (m, 3H, Ph + C6H4), 7.28–7.38 (m, 7H, Ph + C6H4),
7.62–7.70 (m, 4H, Ph + C6H4). 13C NMR (CDCl3): d 4.32, 22.05,
125.46 (d, J = 12.4 Hz), 128.52, 130.75, 131.17, 132.06 (d, J =
10.2 Hz), 132.31, 133.31 (d, J = 12.7 Hz), 133.80, 135.10, 135.84,
137.22, 142.64 (d, J = 8.1 Hz). 31P NMR (CDCl3): d 1.65.
=
[LiCH(SiMe3)C6H4{(PPh2 NSiMe3)-2}(OEt2)] (6). To a
solution of 2 (0.375 g, 0.86 mmol) in Et2O (10 cm3) at about
−30 ◦C was added dropwise LiBun (0.35 cm3, 2.5 M solution in
hexanes, 0.87 mmol) with stirring. The solution was stirred at
room temperature for 6 h and then filtered. Concentration of the
filtrate gave yellow–orange crystals (0.40 g, 90%). mp 95–97 ◦C
(Found: C, 67.88; H, 8.17; N, 2.63%. C29H43NOPLiSi2 requires
1
C, 67.54; H, 8.40; N, 2.72%). H NMR (C6D6): d 0.20 (s, 9H,
SiMe3), 0.30 (s, 9H, SiMe3), 1.08 (t, J = 7.0 Hz, 6H, Et2O),
2.97 (s, 1H, CH), 3.23 (q, J = 7.0 Hz, 4H, Et2O), 5.94–6.02
(m, 1H, Ph + C6H4), 6.56–6.64 (m, 1H, Ph + C6H4), 6.98 (t,
J = 7.5 Hz, 6H, Ph + C6H4), 7.10–7.24 (m, 7H, Ph + C6H4),
7.50–8.20 (b, 4H, Ph + C6H4). 13C NMR (C6D6): d 2.02, 4.05 (d,
J = 3.8 Hz), 14.78, 59.15, 66.32, 106.99,(d, J = 14.6 Hz), 123.33
(d, J = 10.0 Hz), 128.26, 130.74, 131.06, 131.44, 132.37 (d, J =
10.1 Hz), 133.19 (d, J = 10.3 Hz), 134.90 (d, J = 14.9 Hz),
157.21 (d, J = 10.4 Hz). 31P NMR (C6D6): d 20.74.
=
(o-Me3SiCH2C6H4)PPh2 NSiMe3 (2). To a solution of 1
(2.34 g, 6.44 mmol) and tmen (1 cm3, 6.63 mmol) in hexane
(30 cm3) at about −30 ◦C was added dropwise LiBun (2.9 cm3,
2.25 M solution in hexanes, 6.53 mmol) with stirring. The
solution was warmed to room temperature and stirred for 6 h.
Volatiles were removed in vacuo and the residue was dissolved
in Et2O (30 cm3). To the solution was added Me3SiCl (0.9 cm3,
7.04 mmol) at about −80 ◦C. The mixture was stirred overnight
at room temperature and then filtered. The filtrate was distilled
in vacuo to remove solvent and tmen. The residual solid was
recrystallised from hexane to give colourless crystals (2.66 g,
95%), mp 122–124 ◦C (Found: 68.07; H, 7.66; N, 2.91%.
=
Me2Si[CH2C6H4(PPh2 NSiMe3)-2]2 (7). To a solution of 1
(2.215 g, 6.09 mmol) in Et2O (30 cm3) at about −30 ◦C was
added dropwise LiBun (2.44 cm3, 2.5 M solution in hexanes,
6.1 mmol) with stirring. The solution was stirred at room
temp◦erature for 5 h. The resulting solution was cooled to about
−80 C and Me2SiCl2 (0.37 cm3, 3.04 mmol) was added. The
mixture was stirred overnight at room temperature and then
filtered. Solvent was removed from the filtrate to give white solid.
Recrystallisation of the solid from hexane afforded compound
1
C25H34NPSi2 requires C, 68.92; H, 7.87; N, 3.21%). H NMR
(CDCl3): d −0.14 (s, 9H, SiMe3), −0.03 (s, 9H, SiMe3), 2.60 (s,
2H, CH2), 6.98–7.15 (m, 3H, Ph + C6H4), 7.25–7.30 (m, 1H,
Ph + C6H4), 7.40–7.46 (m, 6H, Ph + C6H4), 7.55–7.62 (m, 4H,
Ph + C6H4). 13C NMR (CDCl3): d −0.66, 4.04 (d, J = 3.1 Hz),
24.66 (d, J = 4.1 Hz), 123.45, 128.33 (d, J = 11.9 Hz), 130.63,
130.66, 130.72, 132.14 (d, J = 10.1 Hz), 133.76, 133.83 (d, J =
13.5 Hz), 137.06, 146.77 (d, J = 7.7 Hz). 31P NMR (CDCl3): d
4.06.
◦
7 (1.67 g, 70%), mp 100–106 C (Found: C, 70.67; H, 7.49; N,
3.57%. C46H56N2P2Si3 requires C, 70.55; H, 7.21; N, 3.58%). 1H
NMR (CDCl3): d −0.38 (s, 6H, SiMe2), −0.06 (s, 18H, SiMe3),
2.55 (s, 4H, CH2), 6.93–7.00 (m, 4H, Ph + C6H4), 7.07–7.13 (m,
2H, Ph + C6H4), 7.20–7.26 (m, 2H, Ph + C6H4), 7.36–7.46 (m,
12H, Ph + C6H4), 7.54–7.61 (m, 8H, Ph + C6H4). 13C NMR
(CDCl3): d −2.11, 4.10, 24.33, 123.34 (d, J = 13.2 Hz), 128.23
(d, J = 11.8 Hz), 130.59, 130.65 (d, J = 2.6 Hz), 131.03 (d, J =
10.1 Hz), 131.20, 132.15 (d, J = 10.0 Hz), 132.64, 133.84 (d,
J = 14.0 Hz), 135.63, 136.94, 146.43 (d, J = 8.1 Hz). 31P NMR
(C6D6): d 2.62.
Compound 2 was also prepared by lithiation of 1 in Et2O and
then treatment with Me3SiCl.
=
[LiCH2C6H4{(PPh2 NSiMe3)-2}(tmen)] (3). To a solution
of 1 (0.968 g, 2.66 mmol) and ◦tmen (0.4 cm3, 2.65 mmol) in
hexane (25 cm3) at about −30 C was added dropwise LiBun
(1.2 cm3, 2.25 M solution in hexanes, 2.7 mmol) with stirring.
The solution was stirred at room temperature for 6 h and then
filtered. Concentration of the filtrate gave red crystals (1.05 g,
81%), mp 129–131 ◦C (Found: C, 68.91; H, 8.24; N, 8.33%.
=
[Li2{CHC6H4(PPh2 NSiMe3)-2}2SiMe2·(0.5OEt2)] (8·0.5-
OEt2). To a stirred solution of 7 (0.345 g, 0.44 mmol) in Et2O
(20 cm3) at about −80 ◦C was added dropwise LiBun (0.36 cm3,
2.5 M solution in hexane, 0.9 mmol). The mixture was allowed
to warm to room temperature and stirred overnight. The red
solution was filtered and the filtrate was concentrated to give
yellow orange crystals identified by NMR spectra as 8·0.5Et2O
(0.268 g, 73%), mp 70–74 ◦C (Found: C, 69.57; H, 6.49; N, 3.27%.
C46H54N2P2Si3Li2·0.5Et2O requires C, 69.29; H, 7.15; N, 3.37%.).
1H NMR (C6D6): d 0.06 (s, 3H, SiMe), 0.13 (s, 3H, SiMe), 0.35
(s, 18 H, SiMe3), 2.98 (s, 2H, CH), 1.11 (t, J = 7.0 Hz, 3H, Et2O),
3.26 (q, J = 7.0 Hz, 2H, Et2O), 6.73–6.78 (m, 2H, Ph + C6H4),
7.03–7.07 (m, 16H, Ph + C6H4), 7.20–7.27 (m, 2H, Ph + C6H4),
7.63–7.72 (m, 6H, Ph + C6H4), 7.78–7.87 (m, 2H, Ph + C6H4).
13C NMR (C6D6): d 4.31 (d, J = 3 Hz), 4.61 (d, J = 3.2 Hz),
15.57, 24.76 (d, J = 3.9 Hz), 65.92, 123.57 (d, J = 13.3 Hz),
128.83 (d, J = 7.4 Hz), 130.76 (d, J = 2.6 Hz), 132.07 (d, J =
10.1 Hz), 132.42 (d, J = 10 Hz), 133.26 (d, J = 10.2 Hz), 134.18
(d, J = 14 Hz), 136.27, 137.56, 147.14 (d, J = 7.9 Hz). 31P NMR
(C6D6): d 4.80.
1
C28H41N3PliSi requires C, 69.25; H, 8.51; N, 8.65%). H NMR
(C6D6): d 0.25 (s, 9H, SiMe3), 1.88 (s, 4H, tmen), 2.08 (s, 12H,
tmen), 3.07 (s, 1H, CH2), 3.17 (s, 1H, CH2), 5.63–5.68 (m, 1H,
Ph + C6H4), 6.41–6.49 (m, 1H, Ph + C6H4), 6.61 (t, J = 6.3 Hz,
1H, Ph + C6H4), 6.75 (t, J = 7.8 Hz, 1H, Ph + C6H4), 7.13–7.19
(m, 6H, Ph + C6H4), 7.60–8.35 (b, 4H, Ph + C6H4). 13C NMR
(C6D6): d 5.20, 46.71, 57.38, 59.09, 96.35, 98.04, 101.96 (d, J =
14.6 Hz), 122.65 (d, J = 10.6 Hz), 127.16, 128.16, 130.66 (d, J =
7.2 Hz), 133.48 (d, J = 9.7 Hz), 135.26 (d, J = 14.3 Hz), 136.21,
153.64 (d, J = 10.7 Hz). 31P NMR (C6D6): d 23.46.
=
[LiCH(SiMe3)C6H4{(PPh2 NSiMe3)-2}(tmen)] (4). To a
solution of 2 (1.90 g, 4.36 mmol) a◦nd tmen (0.66 cm3, 4.37 mmol)
in hexane (35 cm3) at about −30 C was added dropwise LiBun
(2 cm3, 2.25 M solution in hexanes, 2.7 mmol) with stirring.
The solution was stirred at room temperature for 6 h and then
filtered. Concentration of the filtrate gave red crystals (2.15 g,
88%), mp 136–138 ◦C (Found: C, 66.44; H, 8.60; N, 7.10%.
C31H49N3PLiSi2 requires C, 66.75; H, 8.85; N, 7.53%). 1H NMR
(C6D6): d 0.25 (s, 9H, SiMe3), 0.31 (s, 9H, SiMe3), 1.90 (s, 4H,
tmen), 2.08 (s, 12H, tmen), 2.88 (s, 1H, CH), 5.88–5.95 (m, 1H,
Reaction of complex 4 with PhCN. To the solution of
complex 4 (0.762 g, 1.366 mmol) in Et2O (15 cm3) was added
D a l t o n T r a n s . , 2 0 0 5 , 9 9 6 – 1 0 0 1
9 9 9

View Article Online
Table 1 Details of the X-ray structure determinations of compounds 2, 3, 5, 6 and 9
2
3
5
6
9
Empirical formula
Formula weight/u
Crystal system
Space group
C25H34NPSi2
435.68
Monoclinic
C28H41LiN3PSi
485.64
Orthorhombic
C56H82Li2N4P2Si4
999.44
C29H43LiNOPSi2
515.73
Monoclinic
C38H54LiN4PSi2
660.94
Monoclinic
Triclinic
¯
P21/n
Pbca
P1
P21/n
P21/c
˚
a/A
8.677(2)
11.776(3)
26.127(7)
90
19.514(4)
16.239(3)
37.215(6)
90
10.679(3)
11.054(3)
15.246(4)
87.212(5)
77.795(5)
61.351(5)
1540.7(8)
1
10.780(5)
20.347(9)
14.692(6)
90
10.430(3)
15.305(5)
25.749(6)
90
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
94.496(6)
90
2661.4(12)
4
1.087
936
0.204
1.56 to 25.02
10812
90
90
11793(4)
16
1.094
4192
0.153
1.51 to 22.50
38788
92.382(9)
90
3220(2)
90.376(8)
90
4110(2)
3
˚
V/A
Z
4
4
Dc/g cm−3
1.077
538
0.184
2.10 to 26.35
8812
1.064
1112
0.179
2.00 to 25.00
16380
1.068
1424
0.154
1.55 to 26.42
23237
F(000)
l/mm−1
h range for data collection/◦
No. reflns. collected
No. indep. reflns. (Rint
)
4698 (0.0784)
4698/0/268
0.963
7718 (0.1595)
7718/248/704
0.992
R1 = 0.0647
wR2 = 0.1134
R1 = 0.1572
wR2 = 0.1430
0.238 and −0.234
6183 (0.0347)
6183/0/316
1.009
R1 = 0.0538
wR2 = 0.1215
R1 = 0.1047
wR2 = 0.1439
0.398 and −0.376
5663 (0.0867)
5663/0/324
0.978
R1 = 0.0605
wR2 = 0.1258
R1 = 0.1529
wR2 = 0.1594
0.220 and −0.289
8397 (0.1010)
8397/0/426
0.927
R1 = 0.0561
wR2 = 0.1068
R1 = 0.1571
wR2 = 0.1472
0.244 and −0.245
No. data/restraints/params
Goodness of fit on F2
Final R indicesa [I > 2r(I)]
R1 = 0.0529
wR2 = 0.1027
R1 = 0.1292
wR2 = 0.1401
0.274 and −0.268
R indices (all data)
−3
˚
Largest diff peak and hole/e A
ꢀ
ꢀ
ꢀ
ꢀ
a R1 = ꢀFo| − |Fcꢀ/ |Fo|; wR2 = [ w(F2o − F2c )2/ w(F4o)]1/2
.
PhCN (0.14 cm3, 1.37 mmol) at about −80 ◦C. The mixture
was warmed to room temperature and stirred overnight. The
red solution was filtered and the filtrate concentrated to give
yellow–orange crystals of complex 9 (0.81 g, 90%), mp 138–
140 ◦C (Found: C, 69.19; H, 7.94; N, 8.93%. C38H54N4PLiSi2
requires C, 69.05; H, 8.23; N, 8.48%). 1H NMR (C6D6): d 0.31
(s, 9H, SiMe3), 0.36 (s, 9H, SiMe3), 1.61 (s, 4H, tmen), 1.86 (s,
12H, tmen), 6.09 (s, 1H, CH), 6.77 (t, J = 6.9 Hz, 1H, Ph +
C6H4), 7.16 (s, 6H, Ph + C6H4), 7.26–7.29 (m, 6H, Ph + C6H4),
7.68–7.76 (m, 1H, Ph + C6H4), 7.88–7.95 (m, 4H, Ph + C6H4),
9.86 (t, J = 6.6 Hz, Ph + C6H4). 13C NMR (C6D6): d 4.44, 4.66,
45.45, 56.57, 100.94, 118.43 (d, J = 14.0 Hz), 119.64, 124.54,
126.07, 127.41, 128.56, 130.26, 131.90, 132.74 (d, J = 10.0 Hz),
135.81 (d, J = 13.0 Hz), 136.33, 137.60, 147.33 (d, J = 7.8 Hz),
150.02, 166.19. 31P NMR (C6D6): d 4.79.
area detector at 293(2) K with graphite-monochromated Mo Ka
˚
radiation (k = 0.71073 A). A semi-empirical absorption correc-
tion was applied to the data of 2 and 6. The structures were solved
by direct methods using SHELXS-9720 and refined against F2 by
full-matrix least-squares using SHELXL-97.21 For complex 3 the
carbon atoms of trimethylsilyl and tmen are disordered in one
of the two molecules in the asymmetric unit and the ordered
molecule is shown in Fig. 2. Crystal data and experimental
details of the structure determinations are listed in Table 1.
CCDC reference numbers 257913-257917. See http://www.
rsc.org/suppdata/dt/b4/b418389d/ for crystallographic data
in CIF or other electronic format.
Acknowledgements
We are grateful for financial support of this work from NSFC
(Grant No. 20272056 and 20072035). We wish to acknowledge
Professors H.-G. Wang and H.-B. Song for determining the
crystal structures.
Reaction of complex 6 with 1,4-dicyanobenzene. To the
solution of complex 6 (0.672 g, 1.303 mmol) in hexane (20 cm3)
was added 1,4-dicyanobenzene (0.083 g, 0.648 mmol) at about
−80 ◦C. The mixture was warmed to room temperature and
stirred overnight. A deep red precipitate was formed. The
mixture was filtered and the residual solid was dissolved in
Et2O. Filtration of the solution and concentration of the filtrate
gave red–orange crystalline 10 (0.655 g, 87%) (Found: C, 68.42;
H, 8.31; N, 4.74%. C66H90N4P2O2Li2Si4 requires C, 68.36; H,
7.82; N, 4.83%). 1H NMR (C6D6): d 0.08 (s, 18H, SiMe3), 0.52
(s, 18H, SiMe3), 1.26 (t, J = 7 Hz, 24H, Et2O), 3.41 (q, J =
7 Hz, 16H, Et2O), 6.16 (s, 2H CH), 7.09–7.35 (m, 19H, Ph +
C6H4), 7.65–7.72 (m, 2H, Ph + C6H4), 7.87–7.93 (m, 1H, Ph +
C6H4), 7.95–8.09 (m, 10H, Ph + C6H4). 13C NMR (C6D6): d
1.91, 5.11 (d, J = 4.1 Hz), 46.68, 57.69, 60.20, 105.40 (d, J =
14.7 Hz), 106.02, 107.68, 123.84 (d, J = 10.3 Hz), 128.24, 128.56,
130.66–130.77 (m), 130.86–130.95 (m), 132.18 (d, J = 10.1 Hz),
132.37 (d, J = 10.1 Hz), 133.29 (d, J = 10.0 Hz), 135.01 (d, J =
14.9 Hz), 137.15, 159.18 (d, J = 10.9 Hz). 31P NMR (C6D6): d
21.65.
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D a l t o n T r a n s . , 2 0 0 5 , 9 9 6 – 1 0 0 1
1 0 0 1