Synthesis and crystal structures of antimony(III) complexes with a bis(amino)silane ligand

Article abstract of DOI:10.1002/zaac.201200471

Bis(amino)silane bearing bulky substituents on nitrogen, LH₂ [L = Me₂Si(NDipp)₂, Dipp = 2, 6-diisopropylphenyl] was reacted with nBuLi (ratio 1:1 and 1:2) in toluene. The Me₂Si(LiNDipp) ₂ was treated with SbCl₃ in a 1:1 ratio to yield the four-membered SiN₂Sb ring compound of composition [η²(N,N)-Me₂Si(NDipp)₂SbCl] (1). The mono lithiated bis(amino)silane was used to synthesize the monodentate heterotetraatomic complex [(η¹-Me₂SiNDipp) NHDippSbCl₂] (2) by the reaction with SbCl₃. The complexes were characterized by ¹H and ¹³C NMR, elemental analysis, IR, and single-crystal X-ray structural analysis. Copyright

Full text of DOI:10.1002/zaac.201200471

ARTICLE
DOI: 10.1002/zaac.201200471
Synthesis and Crystal Structures of Antimony(III) Complexes With a
Bis(amino)silane Ligand
Xiaoli Ma,*[a] Yi Ding,[a] Herbert W. Roesky,*[b] Shuai Sun,[a] and Zhi Yang[a]
Keywords: Bis(amino)silane; Bulky chelating ligand; Heterocyclic complex; Antimony
Abstract. Bis(amino)silane bearing bulky substituents on nitrogen,
LH2 [L = Me2Si(NDipp)2, Dipp = 2,6-diisopropylphenyl] was reacted
with nBuLi (ratio 1:1 and 1:2) in toluene. The Me2Si(LiNDipp)2 was
The mono lithiated bis(amino)silane was used to synthesize the mono-
dentate heterotetraatomic complex [(η1-Me2SiNDipp)NHDippSbCl2]
(2) by the reaction with SbCl3. The complexes were characterized by
treated with SbCl3 in a 1:1 ratio to yield the four-membered SiN2Sb 1H and 13C NMR, elemental analysis, IR, and single-crystal X-ray
ring compound of composition [η2(N,N)-Me2Si(NDipp)2SbCl] (1). structural analysis.
atoms. However most of the reported compounds contain two
ligands, whereas those with one ligand are rare. Herein, we
report on two SbIII compounds with a bis(amino)silane type as
Introduction
In recent years silicon containing heteroatomic compounds
attract much research interest.[1] Moreover metal compounds
mono and bidentate ligand, respectively.
supported by chelating bis(imido) ligands have been reported
by Brookhart et al. and Gibson et al. They were used for the
polymerization of olefins showing excellent activities.[2] Bis(a-
mino)silane Me2Si(ArNH)2 could serve as a very useful chelat-
ing ligand and may have a marked influence on the activity of
the resulting complex in catalysis due to the presence of the
silicon atom close to the ligating nitrogen atoms.[3]
The Si–N bonds in bis(amino)silane are rather strong, while
Experimental Section
General Procedures: All manipulations were carried out in a purified
nitrogen atmosphere using Schlenk techniques or inside a Mbraun MB
150-GI glovebox. All solvents were distilled from Na/benzophenone
ketyl prior to use. LH2 was prepared as described in the literature.[4]
Commercially available chemicals were purchased from J&K chemical
or Aldrich and used as received. 1H and 13C NMR spectra were re-
corded with a Varian 400 spectrometer. Melting points were measured
in sealed glass tubes and are not corrected. Elemental analyses were
performed with a Elementar Vario Micro Cube.
it is desirable to attach bulky R groups to the silicon and nitro-
gen atoms to achieve increased kinetic stability of the low-
coordinate metal. There are a few examples reported, such as:
[Me2Si(NDipp)2]ZrCl2(THF)2,[4] {Me2Si(NDipp)2}XMY (M =
Mo, Zn, Mn, Cd),[5] [iPr2Si(NDipp)2]M: (M = Ge, Sn),[6] [η2-
(N,N)-Me2Si(NDipp)2M·nTHF] (M = Ca, Sr, Ba),[7] [Ph2Si-
(NDipp)2]Sn,[8] {[Me2Si(NDipp)2]Mg}2,[9] [(2,6-Et2C6H3Ni)
(2,6-Et2C6H3NH)SiPh2],[10] [η2-(N,N)-R2Si(DippN)2M] (M =
[η2(N,N)-Me2Si(NDipp)2SbCl] (1): LH2 (0.410 g, 1 mmol) was dis-
solved in toluene (20 mL) and 2 equiv. of nBuLi (1.6 m in hexane,
1.3 mL, 2.0 mmol) were added drop by drop at 0 °C via syringe. The
mixture was allowed to warm to room temperature. The suspension
was stirred for 6 h at room temperature and further cooled to 0 °C,
anhydrous SbCl3 (0.23, 1.0 mmol) in toluene (5 mL) was added drop
by drop (Scheme 1). The solution was allowed to warm to room tem-
perature and stirred for 24 h. The solvent was removed in vacuo and
the obtained solid was extracted with n-hexane (20 mL). The extrac-
tion was filtered. The filtrate was reduced in volume in vacuo and
stored at –35 °C in a freezer for crystallization. Product 1 was isolated
as colorless crystals. Yield: 0.50 g (88%). Mp: 171–172 °C.
C26H40ClN2SbSi (565.89): calcd. C 55.18; H 7.12; N 4.95%; found C
56.02; H 7.26; N 4.82%. 1H NMR (400.18 MHz, CDCl3, 298 K,
ppm): δ = 0.34 (s, 3 H, SiMe2), 7.14–7.37 (m, 6 H, Ar–H), 3.81–4.22
[br., 4 H, CH(CH3)2], 1.26–1.44 [m, 24 H, CH(CH3)2], 0.65 (s, 3 H,
SiMe2) ppm. 13C NMR (100.63 MHz, CDCl3, 298 K, ppm): δ = 147.4,
137.8, 125.1, 123.8 (p-, m-, o-, i-C of Ar), 28.1 (CHMe2), 27.6
(CHMe2), 25.5 (CHMe2), 3.8 (SiMe2), 2.7 (SiMe2) ppm. IR (KBr): ν˜
= 2966 (s), 1439 (m) cm–1.
Ge, Sn, Pb),[11] {(Me2Si)[(2,6-R1 -4-R2-C6H2)N]2}LnN(SiMe3)2-
2
(THF) (Ln = Yb, Y, Eu, Sm, Nd),[12] and [(Ph2Si(Nar)2)2Eu-
{K(THF)2}2].[13] These compounds with a variety of back-
bones were prepared by the salt metathesis reaction of the ap-
propriate dilithiated diamide with MCln. They show a high de-
gree of thermal stability compared to the corresponding species
with bulky substituents both at the silicon and the nitrogen
* Dr. X. Ma
Fax: +86-10-68914503
E-Mail: maxiaoli@bit.edu.cn
* Prof. Dr. H. W. Roesky
Fax: +49-551-39-3373
E-Mail: hroesky@gwdg.de
[a] School of Chemical Engineering and Environment
Beijing Institute of Technology
100081 Beijing, P. R. China
[b] Institut für Anorganische Chemie
Georg-August-Universität Göttingen
Tammannstrasse 4
[(η1-Me2SiNDipp)NHDippSbCl2] (2): The preparation of 2 is like
that of 1 except equimolar nBuLi (1.6 m in hexane, 0.7 mL, 1.1 mmol)
37077 Göttingen, Germany
Z. Anorg. Allg. Chem. 2013, 639, (1), 49–52
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
49

X. Ma, Y. Ding, H. W. Roesky, S. Sun, Z. Yang
ARTICLE
Scheme 1. Preparation of compounds 1 and 2.
Compounds 1 and 2 were characterized by 1H and 13C NMR
and SbCl3 (0.23, 1.0 mmol) in toluene were used. Product 2 was iso-
lated as colorless crystals. Yield: 0.49 g (82%). Mp: 143–145 °C.
C26H41Cl2N2SbSi (602.35): calcd. C 51.84; H 6.86; N 4.64%; found
C 51.65; H 6.52; N 4.94%. 1H NMR (400.18 MHz, CDCl3, 298 K,
ppm): δ = 7.18–7.37 (m, 6 H, Ar–H), 4.64 (s, 1 H, N–H), 3.87 [septet,
1 H, CH(CH3)2], 3.62 [septet, 1 H, CH(CH3)2], 3.48 [septet, 1 H,
CH(CH3)2)], 3.11 [septet, 1 H, CH(CH3)2], 1.15–1.52 [m, 24 H,
CH(CH3)2], 0.31 (s, 6 H, SiMe2) ppm. 13C NMR (100.63 MHz,
CDCl3, 298 K, ppm): δ = 147.8, 147.0, 141.2, 137.5, 125.9, 124.4,
123.5, 122.6 (p-, m-, o-, i-C of Ar), 29.0, 28.6 (CHMe2), 27.2, 26.3,
investigation in CDCl3 solution, IR, as well as by elemental
1
analysis. In the H NMR spectrum, compound 1 exhibits two
resonances for the SiMe2 protons (δ = 0.34 and 0.65 ppm) and
one broad resonance for the CHMe2 protons in the range 3.81–
4.22 ppm with the intensity of 3:2, showing the characteristic
bis(amino)silane skeleton. Compound 2 exhibits SiMe2 protons
(δ = 0.31 ppm), four resonances for the CHMe2 (δ = 3.11, 3.48,
3.62, 3.87 ppm) with equal intensity, and one sharp resonance
25.6, 24.2, (CHMe2), 3.5 (SiMe2) ppm. IR (KBr): ν˜ = 3394 (w, NH), for the N–H proton (δ = 4.64 ppm), showing the characteristic
2966 (s), 1437 (m) cm–1.
aminosilane skeleton.
Compound 1 crystallizes in the orthorhombic space group
Single Crystal X-ray Structure Determination and Refinement:
Pna21 with one molecule in the symmetric unit.[17] Compound
The crystallographic data for 1 and 2 were collected with a Rigaku
2 crystallizes in the triclinic space group P1 with one molecule
AFC10 Saturn724+ (2ϫ2 bin mode) diffractometer equipped with
in the asymmetric unit.[18]
The molecular structure of 1 is shown in Figure 1. Selected
bond lengths and bond angles are listed in Table 1.
graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å). Empirical
absorption correction was applied using the SADABS program.[14]
Structures were solved by direct methods[15] and refined by full-matrix
least-squares on F2 using the SHELXL-97 program.[16] All non-hydro-
gen atoms were located by difference Fourier synthesis and refined
anisotropically, and hydrogen atoms were included using the riding
model with Uiso related to the Uiso of the parent atoms.
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-897265 (1) and CCDC-897264 (2) (Fax: +44-1223-
336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.
ac.uk).
Figure 1. Molecular structure of 1. Thermal ellipsoids are drawn at
50% level, and the hydrogen atoms are omitted for clarity.
Results and Discussion
Table 1. Selected bond lengths /Å and angles /° for compound 1.
LH2 reacts with 2 equiv. of nBuLi in toluene for 6 h to LLi2
without isolation (Scheme 1), then antimony(III) trichloride
was added in equimolar amount, which resulted in the product
[η2(N,N)-Me2Si(NDipp)2SbCl] (1). The reaction of LH2 with
equimolar amount of nBuLi in toluene for 6 h yields L(H)Li,
which was treated with antimony(III) trichloride in a molar
ratio of 1:1, which resulted in the product [(η1-Me2SiNDipp)
NHDippSbCl2] (2). Compounds 1 and 2 were isolated after
Sb1–N1
Sb1–Cl1
Si1–N2
N1–Si1–N2
N2–Sb1–Cl1
Si1–N2–Sb1
2.018(4)
2.3899(17)
1.763(5)
88.7(2)
101.73(13)
97.9(2)
Sb1–N2
Si1–N1
N1–Sb1–N2
N1–Sb1–Cl1
Si1–N1–Sb1
2.029(5)
1.754(5)
74.83(18)
98.69(17)
98.6(2)
Compound 1 adopts a N2SiSb four-membered ring with tri-
growing colorless crystals from the concentrated n-hexane gonal planar coordinated nitrogen atoms. The SiN2Sb four-
solutions. All compounds are soluble in toluene, benzene, and membered ring is essentially planar with the sum of inner
trichloromethane.
50 www.zaac.wiley-vch.de
angles of 360.03°. The bond angles around the antimony atom
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2013, 49–52

Antimony(III) Complexes With a Bis(amino)silane Ligand
of N1–Sb1–N2 (74.83°), N1–Sb1–Cl1 (101.73°), and N2–
Sb1–Cl2 (98.69°) are highly distorted and could be described
as a quasi-tetrahedral arrangement. The angle of N1–Sb1–N2
(74.83°) is much sharper when compared with the one in a
regular tetrahedon (109°28Ј). This might be due to the SiN2Sb
ring strain. Compound 1 presents a rare antimony heterocycle
featuring a N2SiSb core structurally characterized by a X-ray
single crystal structural investigation.
Acknowledgements
We are grateful for financial support by the National Nature Science
Foundation of China (21001016, 20901009); the Research Fund for
the Doctoral Program of Higher Education of China (2009110112043);
the Program of NCET-10–0050. Support of the Göttinger Akademie
der Wissenschaften is highly acknowledged.
The molecular structure of 2 is shown in Figure 2. Selected
bond lengths and bond angles are listed in Table 2. In the struc-
ture of compound 2 the antimony atom is coordinated to one
nitrogen atom of the ligand, forming a complex with an acyclic
N–Si–N–Sb core. The Sb–N1 bond length in 2 is 2.029 Å,
whereas that of Sb–N2 is 2.66 Å, which demonstrates that
there is no bonding between Sb and N2. The N1–Si–N2 angle
is 97.06° in 2 and 88.7° in 1, the Si–N–Sb angle is 110.35° in
2 and 98.25° in 1, which shows the open structure of the
N2SbSi moiety in 2. The N–Sb–Cl angle is 95.94° in 2, which
is a little smaller when compared with that of 100.21° in 1. To
the best of our knowledge 2 is the first antimony(III) com-
pound supported by a bis(amino)silane monodentate ligand.
References
[1] a) M. Veith, J. Frères, V. Huch, M. Zimmer, Organometallics
2006, 25, 1875–1880; b) M. Veith, M. Zimmer, V. Huch, Z.
Anorg. Allg. Chem. 2009, 635, 674–681; c) M. Veith, A. Rammo,
R. Heim, V. Huch, Z. Anorg. Allg. Chem. 2010, 636, 320–324; d)
M. Veith, A. Rammo, V. Huch, J. Biegler, Z. Anorg. Allg. Chem.
2007, 636, 246–250; e) M. Veith, A. Rammo, O. Schütt, V. Huch,
Z. Anorg. Allg. Chem. 2010, 636, 1212–1221.
[2] a) J. P. G. Britovesk, V. C. Gibson, F. D. Wass, Angew. Chem. Int.
Ed. 1999, 38, 428–447; b) V. C. Gibson, B. S. Kimberley, A. J. P.
White, D. J. Williams, P. Howard, Chem. Commun. 1998, 313–
314; c) L. K. Johnson, C. M. Killian, M. Brookhart, J. Am. Chem.
Soc. 1996, 118, 11664–11665; d) S. D. Ittel, L. K. Johnson, M.
Brookhart, Chem. Rev. 2000, 100, 1169–1204; e) J. Choi, A. H. R.
MacArthur, M. Brookhart, A. S. Goldman, Chem. Rev. 2011, 111,
1761–1779.
[3] a) M. F. Lappert, P. P. Power, A. R. Sanger, R. C. Srivastava,
Metal and Metalloid Amides, Wiley, Chichester 1980, 22–44; b)
W. Frank, V. Petry, E. Gerwalin, G. J. Reiss, Angew. Chem. Int.
Ed. Engl. 1996, 35, 1512–1514; c) K. Bode, U. Klingebiel, Adv.
Organomet. Chem. 1996, 40, 1–43; d) D. C. Haagenson, D. F.
Moser, L. Stahl, R. J. Staples, Inorg. Chem. 2002, 41, 1245–1253;
e) N. Burford, S. Mason, R. E. Spence, J. M. Whalen, J. M. Rich-
ardson, R. D. Rogers, Organometallics 1992, 11, 2241–2250; f)
D. Yang, Y. Ding, H. Wu, W. Zheng, Inorg. Chem. 2012, 51,
7698–7706.
[4] M. S. Hill, P. B. Hitchcock, Organometallics 2002, 21, 3258–
3262.
[5] a) Y. Tsai, Y. Lin, J. Shiang, K. Yu, J. Hwang, J. Am. Chem. Soc.
2006, 128, 13980–13981; b) Y. Tsai, D. Lu, Y. Lin, J. Hwang, J.
Shiang, K. Yu, Chem. Commun. 2007, 4125–4127; c) D. Lu, J.
Shiang, K. Yu, T. Kuo, G. Lee, Y. Wang, Y. Tsai, Angew. Chem.
Int. Ed. 2011, 50, 7611–7615.
[6] S. M. I. Al-Rafia, P. A. Lummis, M. J. Ferguson, R. McDonald,
E. Rivard, Inorg. Chem. 2010, 49, 9709–9717.
Figure 2. Molecular structure of 2. Thermal ellipsoids are drawn at
50% level, and the hydrogen atoms (except N-H) are omitted for
clarity.
[7] D. Yang, Y. Ding, H. Wu, W. Zheng, Inorg. Chem. 2011, 50,
7698–7706.
[8] S. M. Mansell, C. A. Russell, D. F. Wass, Inorg. Chem. 2008, 47,
11367–11375.
[9] C. Pi, L. Wan, Y. Gu, H. Wu, C. Wang, W. Zheng, L. Weng, Z.
Chen, X. Yang, L. Wu, Organometallics 2009, 28, 5281–5284.
[10] N. Palanisami, R. Murugavel, J. Organomet. Chem. 2006, 691,
3260–3266.
Table 2. Selected bond lengths /Å and angles /° for compound 2.
Sb1–N1
Sb1–Cl2
Si1–N2
2.0294 (17)
2.4077(8)
1.775(2)
Sb1–Cl1
Si1–N1
N2–H2n
2.3905(8)
1.7353(18)
0.74(2)
[11] D. Yang, J. Guo, H. Wu, Y. Ding, W. Zheng, Dalton Trans. 2012,
Cl1–Sb1–Cl2 93.79(3)
N1–Si1–N2
N1–Sb1–Cl2
97.06(9)
96.76(5)
41, 2187–2194.
N1–Sb1–Cl1
Si1–N1–Sb1
95.12(5)
110.35(8)
[12] X. Zhu, J. Fan, Y. Wu, S. Wang, L. Zhang, G. Yang, Y. Wei, C.
Yin, H. Zhu, S. Wu, H. Zhang, Organometallics 2009, 28, 3882–
3888.
[13] C. L. Pan, Y. S. Pan, J. Wang, J. F. Song, Dalton Trans. 2011, 40,
6361–6363.
[14] G. M. Sheldrick, SADABS, Empirical Absorption Correction Pro-
gram, University of Göttingen, Göttingen, Germany, 1997.
[15] G. M. Sheldrick, SHELXS-90, Program for Structure Solution,
Acta Crystallogr., Sect. A 1990, 46, 467–473.
Conclusions
We have synthesized and characterized two antimony(III)
chloride complexes with an aminosilane ligand. One of the
complexes exhibits a SiN2Sb four-membered ring, whereas the
second features an acyclic N–Si–N–Sb core. Both complexes
were characterized by single-crystal X-ray structural analysis.
[16] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Re-
finement; University of Göttingen, Germany, 1997.
[17] Crystal data for 1: C26H40ClN2SbSi, Mr = 565.89, orthorhombic,
space group Pna21, a = 17.327(3) Å, b = 8.7112(13) Å, c =
36.648(3) Å, α = β = γ = 90°, V = 5531.5(12) Å3, Z = 8, ρcalcd.
=
Z. Anorg. Allg. Chem. 2013, 49–52
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
51

X. Ma, Y. Ding, H. W. Roesky, S. Sun, Z. Yang
ARTICLE
1.359 g·cm–3, F(000)= 2336, 2.35 Յ θ Յ 30.02, of 33087 reflec-
tions collected, 15047 were independent, R(int)= 0.0474, R1
16801 reflections collected, 8294 were independent, R(int)=
0.0335, R1 = 0.0336, wR2 = 0.0765 [I Ͼ 2σ(I)); The residual
electron density: 0.673/–1.140 e·Å–3. Command “twin” was used
to revise the possible racemic twin of the structure, so there’s no
s. u. given for the Alert Level A in the checkcif file.
=
0.0641, wR2 = 0.1548 [I Ͼ 2σ(I)); The residual electron density:
5.050/–1.877 e·Å–3.
[18] Crystal data for 2: C26H41Cl2N2SbSi, Mr = 602.35, triclinic, space
group P1, a = 8.316(2) Å, b = 9.705(3) Å, c = 18.069(6) Å, α =
91.953(6)°, β = 94.094(6)°, γ = 91.674(5)°, V = 1452.9 (7) Å3, Z
= 2, ρcalcd. = 1.377 gcm–3, F(000)= 620, 2.10 Յ θ Յ 30.02, of
Received: October 25, 2012
Published Online: December 20, 2012
52
www.zaac.wiley-vch.de
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2013, 49–52