- Email: [email protected]
Easy access to chiral penta- and hexacoordinate silicon compounds
Inorganic Chemistry Communications 9 (2006) 806–809 www.elsevier.com/locate/inoche
Easy access to chiral penta- and hexacoordinate silicon compounds Uwe Bo¨hme *, Sebastian Wiesner, Betty Gu¨nther Institut fu¨r Anorganische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, 09596 Freiberg, Deutschland, Germany Received 13 April 2006; accepted 7 May 2006 Available online 13 May 2006
Abstract Chiral penta- and hexacoordinate silicon complexes are accessible with O,N,O-ligands, which contain exclusively one stereoisomer prepared from amino acids of the chiral pool. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Hypercoordinate; Chiral silicon; Complexes
The chemistry of penta- and hexacoordinate silicon compounds has been extensively investigated in the last decade [1–4]. Compounds of this type are interesting from a structural point of view as well as due to the activation of bonds in the vicinity of the central silicon atom [4a]. Chiral hypercoordinate silicon compounds are involved in the chirality transfer from silicon to carbon [5] and might serve as model compounds for biological transport processes of silicon [6]. Until today there is no simple method to prepare chiral hypercoordinate silicon compounds. Recently, the synthesis of zwitterionic k5Si-silicates with pentacoordinate silicon anions has been described [7]. A number of highly elaborate syntheses for chiral tetracoordinate silicon compounds have been developed where the silicon atom is the chiral center [8]. The alternative approach is to locate the chirality at a site attached to the silicon atom usually with a chiral ligand or substituent [9]. We report here our recent results, which show that chiral hypercoordinate silicon compounds can be obtained in a straightforward synthesis from O,N,O-chelate ligands and chlorosilanes. The chiral ligands 1a and 1b were prepared in the two-step route shown in Scheme 1. The preparative procedure follows the work of Braun et al. who had used this type of ligands to obtain chiral titanium complexes [10]. Both ligands reacted with SiCl4 and R2SiCl2 in the *
Corresponding author. E-mail address: [email protected] (U. Bo¨hme).
1387-7003/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2006.05.002
presence of excess NEt3 to form the desired penta- and hexacoordinate silicon complexes (Scheme 2) [11,12]. The reaction of 1a with SiCl4 gives for instance the hexacoordinate complex 2a. Two diastereomers of penta- and hexacoordinate species are present in solution. Therefore, we find four sets of signals in the NMR spectra of this compound. Fortunately, we were able to obtain crystals suitable for Xray structure analysis [13]. The X-ray structure shows the presence of a hexacoordinate silicon compound, which crystallizes with one disordered molecule, dimethoxyethane, on a special position with only 20% site occupation. Two phenyl rings of the molecule are disordered as well. The asymmetric unit of the molecule is shown in Fig. 1. A crystallographic C2 axis generates the full molecule. The coordination sphere is shown in Fig. 2. The silicon atom is in a slightly distorted octahedral environment with angles between 86.2° and 93.9°. The Si–N distance is longer than the Si–O distances. R-phenylglycine was used as the starting material. The configuration of the chiral O,N,Oligand is R as can be seen from the configuration at C(2) and C(2a) in Fig. 2. Ligand 1b was reacted with Me2SiCl2, Ph2SiCl2, and (Vinyl)2SiCl2. The reaction with the dichlorodialkylsilanes gave the desired pentacoordinate complexes 3a–3c. The X-ray structure analysis of [(S)-2-(N-salicylideneamino)-3methyl-1,1-diphenyl-1-butanolato(2-)-jN,jO,jO 0 ]silicondimethyl 3a confirms the formation of pentacoordinate silicon complexes (Fig. 3) [14]. The Si–O distances are substantial,
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809 1
R
1
O
ClH 3 N
Ph
R i
*
Ph
*
OMe
807
H 2N
OH
2
R
O ii + OH
1
Ph
R
Ph *
2
R
OH
N
OH
Scheme 1. Synthesis of chiral ligands 1a (R1 = Ph, R2 = Me) and 1b (R1 = i-Pr, R2 = H). Reagents: (i) excess PhMgBr in Et2O, workup with HCl/H2O to obtain the amine hydrochloride; KOH in methanol; extraction with CH2Cl2; (ii) o-hydroxyacetophenone in methanol/CH2Cl2 in the presence of Na2SO4 at 0 °C for 1a, salicylaldehyde in methanol in the presence of Na2SO4 at reflux temperature for 1b.
Fig. 1. ORTEP plot of 2a showing only the asymmetric unit. Selected ˚ ) and angles (°): Si(1)–O(1) 1.723(2), Si(1)–O(2) bond lengths (in A 1.747(3), Si(1)–N(1) 1.917(3), O(1)–Si(1)–O(1a) 91.3(2), O(1)–Si(1)–O(2a) 91.2(1), O(2)–Si(1)–O(2a) 86.3(2), O(1)–Si(1)–N(1) 86.2(1), O(1a)1–Si(1)– N(1) 93.1(1), O(2)–Si(1)–N(1) 93.9(1), O(2a)1–Si(1)–N(1) 86.8(1), O(1)– Si(1)–N(1a) 93.1(1), N(1)–Si(1)–N(1a) 179.0(2), O(1)–Si(1)–O(2) 177.5(1).
˚ . But such long shorter than the distance Si–N with 2.047 A dative Si–N distances have also been found in other pentaand hexacoordinate silicon compounds [4]. The bond dis˚ ) is shorter than Si–C(26) tance Si–C(25) (1.865 A ˚ ), which might be explained with the coordination (1.891 A geometry of this compound. The silicon atom is in a distorted square pyramidal environment with the carbon
R2
R1 Ph
* N
Ph O
O
Si
O Ph
N OH
1
R R2
(R1=Ph, R2=Me) 2a
N R2
Ph
OH
Ph
*
i + SiCl4
*
R1
O
Ph
ii 1
Ph
R
+Cl2SiR32
Ph
*
R2 N
O Si
O
R3 3
R
(R1=i-Pr, R2=H) 3a R3=Me R3=Ph 3b R3=Vinyl 3c
Scheme 2. Synthesis of chiral 5- and 6-coordinate silicon complexes. (i) Reaction in THF in 2:1 ratio of ligand to SiCl4 in the presence of excess NEt3. (ii) Reaction in THF in 1:1 ratio of ligand to Cl2 SiR32 in the presence of excess NEt3.
808
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809
structures and the reactivity of these hypercoordinate silicon compounds will be further investigated. This work was supported by the Fonds der Chemischen Industrie (Degussa AG). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2006. 05.002. References
Fig. 2. Octahedral coordination sphere of 2a. Substituents and hydrogen atoms are omitted for clarity. Symmetry code to generate the second ligand molecule: x, y, z.
˚ ) and angles (°): Fig. 3. ORTEP plot of 3a. Selected bond lengths (in A Si(1)–O(1) 1.716(1), Si(1)–O(2) 1.778(1), Si(1)–C(25) 1.865(2), Si(1)–C(26) 1.891(2), Si(1)–N(1) 2.047(1), O(1)–Si(1)–C(25) 109.77(7), O(2)–Si(1)– C(25) 101.96(7), C(25)–Si(1)–C(26) 108.50(9), C(25)–Si(1)–N(1) 99.99(7), O(1)–Si(1)–N(1) 80.29(5), O(1)–Si(1)–C(26) 90.46(7), O(2)–Si(1)–C(26) 89.67(7), O(2)–Si(1)–N(1) 83.77(5), C(26)–Si(1)–N(1) 151.50(8), O(1)– Si(1)–O(2) 146.43(6).
atom C(25) at the top of the pyramid. The bond angles between C(25) and the atoms O(1), N(1), O(2), and C(26) at the base of the pyramid are about 99.99–109.77°. The angles between the atoms at the base of the pyramid are between 80.29° and 90.46°. The work presented here has allowed us to establish an easy access to chiral penta- and hexacoordinate silicon complexes with O,N,O-ligands bearing chirality. We were able to show that it is possible to utilize chiral O,N,Oligands for the preparation of these complexes. The diverse
[1] (a) R.J.P. Corriu, J.C. Young, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic Silicon Compounds, vol. 1, John Wiley and Sons Ltd., New York, 1989, p. 1241; (b) C. Chuit, R.J.P. Corriu, C. Reye, J.C. Young, Chemical Reviews 93 (1993) 1371; (c) D. Kost, I. Kalikhman, in: Z. Rappoport, Y. Apeloig (Eds.), The Chemistry of Organic Silicon Compounds, vol. 2, John Wiley and Sons Ltd., New York, 1998, p. 1339. [2] (a) D. Kost, I. Kalikhman, Advances in Organometallic Chemistry, in: R. West, A.F. Hill (Eds.), Elsevier, Amsterdam, 2004, p. 1; (b) D. Kost, V. Kingston, B. Gostevskii, A. Ellern, D. Stalke, B. Walfort, I. Kalikhman, Organometallics 21 (2002) 2293. [3] (a) R. Tacke, R. Bertermann, M. Penka, O. Seiler, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 629 (2003) 2415; (b) O. Seiler, R. Bertermann, N. Buggisch, C. Burschka, M. Penka, D. Tebbe, R. Tacke, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 629 (2003) 1403. [4] (a) J. Wagler, U. Bo¨hme, G. Roewer, Angewandte Chemie 114 (2002) 1825; J. Wagler, U. Bo¨hme, G. Roewer, Angewandte Chemie-International Edition in English 41 (2002) 1732; (b) J. Wagler, U. Bo¨hme, E. Brendler, G. Roewer, Zeitschrift fu¨r Naturforschung B 59 (2004) 1348; (c) J. Wagler, U. Bo¨hme, E. Brendler, S. Blaurock, G. Roewer, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 631 (2005) 2907. [5] (a) M. Oestreich, Chemistry – A European Journal 12 (2006) 30; (b) S. Rendler, M. Oestreich Synthesis (2005) 1727. [6] (a) G. Pohnert, Angewandte Chemie 114 (2002) 3299; G. Pohnert, Angewandte Chemie-International Edition in English 41 (2002) 3167; (b) R. Tacke, Angewandte Chemie 111 (1999) 3197; R. Tacke, Angewandte Chemie-International Edition in English 38 (1999) 3015. [7] (a) R. Tacke, R. Bertermann, C. Burschka, S. Dragota, M. Penka, I. Richter, Journal of the American Chemical Society 126 (2004) 14493; (b) S. Dragota, R. Bertermann, C. Burschka, M. Penka, R. Tacke, Organometallics 24 (2005) 5560. [8] (a) R.J.P. Corriu, C. Gue´rin, J.J.E. Moreau, Topics in Stereochemistry 15 (1984) 43; (b) R.J.P. Corriu, C. Guerin, J.J.E. Moreau, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic Silicon Compounds, 1, John Wiley and Sons Ltd., New York, 1989, p. 305; (c) P.J. Stang, A.E. Learned, Journal of Organic Chemistry 54 (1989) 1779; (d) A. Kawachi, H. Maeda, K. Mitsudo, K. Tamao, Organometallics 18 (1999) 4530; (e) M. Omote, T. Tokita, Y. Shimizu, I. Imae, E. Shirakawa, Y. Kawakami, Journal of Organometallic Chemistry 611 (2000) 20; (f) C. Strohmann, M. Bindl, V.C. Fraaß, J. Ho¨rnig, Angewandte Chemie 116 (2004) 1029; (g) C. Strohmann, M. Bindl, V.C. Fraaß, J. Ho¨rnig, Angewandte Chemie-International Edition 43 (2004) 1011.
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809 [9] (a) T.H. Chan, P. Pellon, Journal of the American Chemical Society 111 (1989) 8737; (b) T.H. Chan, K.T. Nwe, Journal of Organic Chemistry 57 (1992) 6107; (c) C. Strohmann, B.C. Abele, K. Lehmen, D. Schildbach, Angewandte Chemie 117 (2005) 3196; (d) C. Strohmann, B.C. Abele, K. Lehmen, D. Schildbach, Angewandte Chemie-International Edition 44 (2005) 3136. [10] R. Fleischer, H. Wunderlich, M. Braun, European Journal of Organic Chemistry (1998) 1063. [11] Electronic supplementary information available: characterising data for all new complexes. [12] General procedure: Ligand 1a or 1b (6 mmol) and triethylamine (15 mmol) were placed in a Schlenk flask and 40 mL of DME added. Chlorosilane was added dropwise at 10 °C (6.2 mmol of dichlorodialkylsilane; 3 mmol of SiCl4, respectively). A white precipitate is formed immediately. The reaction mixture was stirred at room temperature for 2 h and at reflux temperature for 40 h. During that time the mixture became yellow to orange. The solvent was completely removed in vacuo and the residue was treated with nhexane. The insoluble triethylammonium chloride was filtered off, washed with n-hexane and the volume of the filtrate was reduced in vacuo. Storage overnight in the refrigerator yielded the product, which was separated by filtration and dried in vacuo. [13] Crystallographic data for 2a: chemical formula moiety C56H46N2O4Si, C0.80H2O0.40 (dimethoxyethane with 20% site occupation),
809
Mw = 857.06, Tetragonal, P43212, a = b = 11.422(2), c= ˚ a = b = c = 90°, V = 4992.5(14) A ˚ 3, Z = 4, qcalc = 1.140 38.270(8) A Mg/m3, reflections collected/unique 156180/4404 [Rint = 0.0430], refinement method full-matrix least-squares on F2, data/restraints/ parameters 4404/150/391, Final R indices [I > 2r(I)] R1 = 0.072, (all data) R1 = 0.081, absolute structure parameter 0.2(3). The absolute configuration of this structure was assigned according to the configuration of the chiral ligand, since the measured data do not allow unambiguous determination of the absolute structure. Data collected with a Bruker X8 APEX2 diffractometer. Intensities were collected with graphite monochromatised Mo Ka radiation at room temperature. The structure was solved by Direct methods, using the SHELXS program and refined by fullmatrix least-squares method using SHELX97. CCDC No. 271 516. [14] Crystallographic data for 3a: C26H29NO2Si, Mw = 415.59, Ortho˚, rhombic, P212121, a = 11.5450(3), b = 11.8641(3), c = 16.4953(4) A ˚ 3, Z = 4, qcalc = 1.222 Mg/m3, a = b = c = 90°, V = 2259.4(1) A Reflections collected/unique 38266/4199 [Rint = 0.0439], Data/ restraints/parameters 4199/0/275, Final R indices [I > 2r(I)] R1 = 0.028, (all data) R1 = 0.033, Absolute structure parameter 0.00(9). Data collected with a Bruker X8 APEX2 diffractometer. Intensities were collected with graphite monochromatised Mo Ka radiation at 180°C. The structure was solved by Direct methods, using the SHELXS program and refined by full-matrix least-squares method using SHELX97. CCDC No. 288 067.
Easy access to chiral penta- and hexacoordinate silicon compounds Uwe Bo¨hme *, Sebastian Wiesner, Betty Gu¨nther Institut fu¨r Anorganische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, 09596 Freiberg, Deutschland, Germany Received 13 April 2006; accepted 7 May 2006 Available online 13 May 2006
Abstract Chiral penta- and hexacoordinate silicon complexes are accessible with O,N,O-ligands, which contain exclusively one stereoisomer prepared from amino acids of the chiral pool. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Hypercoordinate; Chiral silicon; Complexes
The chemistry of penta- and hexacoordinate silicon compounds has been extensively investigated in the last decade [1–4]. Compounds of this type are interesting from a structural point of view as well as due to the activation of bonds in the vicinity of the central silicon atom [4a]. Chiral hypercoordinate silicon compounds are involved in the chirality transfer from silicon to carbon [5] and might serve as model compounds for biological transport processes of silicon [6]. Until today there is no simple method to prepare chiral hypercoordinate silicon compounds. Recently, the synthesis of zwitterionic k5Si-silicates with pentacoordinate silicon anions has been described [7]. A number of highly elaborate syntheses for chiral tetracoordinate silicon compounds have been developed where the silicon atom is the chiral center [8]. The alternative approach is to locate the chirality at a site attached to the silicon atom usually with a chiral ligand or substituent [9]. We report here our recent results, which show that chiral hypercoordinate silicon compounds can be obtained in a straightforward synthesis from O,N,O-chelate ligands and chlorosilanes. The chiral ligands 1a and 1b were prepared in the two-step route shown in Scheme 1. The preparative procedure follows the work of Braun et al. who had used this type of ligands to obtain chiral titanium complexes [10]. Both ligands reacted with SiCl4 and R2SiCl2 in the *
Corresponding author. E-mail address: [email protected] (U. Bo¨hme).
1387-7003/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2006.05.002
presence of excess NEt3 to form the desired penta- and hexacoordinate silicon complexes (Scheme 2) [11,12]. The reaction of 1a with SiCl4 gives for instance the hexacoordinate complex 2a. Two diastereomers of penta- and hexacoordinate species are present in solution. Therefore, we find four sets of signals in the NMR spectra of this compound. Fortunately, we were able to obtain crystals suitable for Xray structure analysis [13]. The X-ray structure shows the presence of a hexacoordinate silicon compound, which crystallizes with one disordered molecule, dimethoxyethane, on a special position with only 20% site occupation. Two phenyl rings of the molecule are disordered as well. The asymmetric unit of the molecule is shown in Fig. 1. A crystallographic C2 axis generates the full molecule. The coordination sphere is shown in Fig. 2. The silicon atom is in a slightly distorted octahedral environment with angles between 86.2° and 93.9°. The Si–N distance is longer than the Si–O distances. R-phenylglycine was used as the starting material. The configuration of the chiral O,N,Oligand is R as can be seen from the configuration at C(2) and C(2a) in Fig. 2. Ligand 1b was reacted with Me2SiCl2, Ph2SiCl2, and (Vinyl)2SiCl2. The reaction with the dichlorodialkylsilanes gave the desired pentacoordinate complexes 3a–3c. The X-ray structure analysis of [(S)-2-(N-salicylideneamino)-3methyl-1,1-diphenyl-1-butanolato(2-)-jN,jO,jO 0 ]silicondimethyl 3a confirms the formation of pentacoordinate silicon complexes (Fig. 3) [14]. The Si–O distances are substantial,
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809 1
R
1
O
ClH 3 N
Ph
R i
*
Ph
*
OMe
807
H 2N
OH
2
R
O ii + OH
1
Ph
R
Ph *
2
R
OH
N
OH
Scheme 1. Synthesis of chiral ligands 1a (R1 = Ph, R2 = Me) and 1b (R1 = i-Pr, R2 = H). Reagents: (i) excess PhMgBr in Et2O, workup with HCl/H2O to obtain the amine hydrochloride; KOH in methanol; extraction with CH2Cl2; (ii) o-hydroxyacetophenone in methanol/CH2Cl2 in the presence of Na2SO4 at 0 °C for 1a, salicylaldehyde in methanol in the presence of Na2SO4 at reflux temperature for 1b.
Fig. 1. ORTEP plot of 2a showing only the asymmetric unit. Selected ˚ ) and angles (°): Si(1)–O(1) 1.723(2), Si(1)–O(2) bond lengths (in A 1.747(3), Si(1)–N(1) 1.917(3), O(1)–Si(1)–O(1a) 91.3(2), O(1)–Si(1)–O(2a) 91.2(1), O(2)–Si(1)–O(2a) 86.3(2), O(1)–Si(1)–N(1) 86.2(1), O(1a)1–Si(1)– N(1) 93.1(1), O(2)–Si(1)–N(1) 93.9(1), O(2a)1–Si(1)–N(1) 86.8(1), O(1)– Si(1)–N(1a) 93.1(1), N(1)–Si(1)–N(1a) 179.0(2), O(1)–Si(1)–O(2) 177.5(1).
˚ . But such long shorter than the distance Si–N with 2.047 A dative Si–N distances have also been found in other pentaand hexacoordinate silicon compounds [4]. The bond dis˚ ) is shorter than Si–C(26) tance Si–C(25) (1.865 A ˚ ), which might be explained with the coordination (1.891 A geometry of this compound. The silicon atom is in a distorted square pyramidal environment with the carbon
R2
R1 Ph
* N
Ph O
O
Si
O Ph
N OH
1
R R2
(R1=Ph, R2=Me) 2a
N R2
Ph
OH
Ph
*
i + SiCl4
*
R1
O
Ph
ii 1
Ph
R
+Cl2SiR32
Ph
*
R2 N
O Si
O
R3 3
R
(R1=i-Pr, R2=H) 3a R3=Me R3=Ph 3b R3=Vinyl 3c
Scheme 2. Synthesis of chiral 5- and 6-coordinate silicon complexes. (i) Reaction in THF in 2:1 ratio of ligand to SiCl4 in the presence of excess NEt3. (ii) Reaction in THF in 1:1 ratio of ligand to Cl2 SiR32 in the presence of excess NEt3.
808
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809
structures and the reactivity of these hypercoordinate silicon compounds will be further investigated. This work was supported by the Fonds der Chemischen Industrie (Degussa AG). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2006. 05.002. References
Fig. 2. Octahedral coordination sphere of 2a. Substituents and hydrogen atoms are omitted for clarity. Symmetry code to generate the second ligand molecule: x, y, z.
˚ ) and angles (°): Fig. 3. ORTEP plot of 3a. Selected bond lengths (in A Si(1)–O(1) 1.716(1), Si(1)–O(2) 1.778(1), Si(1)–C(25) 1.865(2), Si(1)–C(26) 1.891(2), Si(1)–N(1) 2.047(1), O(1)–Si(1)–C(25) 109.77(7), O(2)–Si(1)– C(25) 101.96(7), C(25)–Si(1)–C(26) 108.50(9), C(25)–Si(1)–N(1) 99.99(7), O(1)–Si(1)–N(1) 80.29(5), O(1)–Si(1)–C(26) 90.46(7), O(2)–Si(1)–C(26) 89.67(7), O(2)–Si(1)–N(1) 83.77(5), C(26)–Si(1)–N(1) 151.50(8), O(1)– Si(1)–O(2) 146.43(6).
atom C(25) at the top of the pyramid. The bond angles between C(25) and the atoms O(1), N(1), O(2), and C(26) at the base of the pyramid are about 99.99–109.77°. The angles between the atoms at the base of the pyramid are between 80.29° and 90.46°. The work presented here has allowed us to establish an easy access to chiral penta- and hexacoordinate silicon complexes with O,N,O-ligands bearing chirality. We were able to show that it is possible to utilize chiral O,N,Oligands for the preparation of these complexes. The diverse
[1] (a) R.J.P. Corriu, J.C. Young, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic Silicon Compounds, vol. 1, John Wiley and Sons Ltd., New York, 1989, p. 1241; (b) C. Chuit, R.J.P. Corriu, C. Reye, J.C. Young, Chemical Reviews 93 (1993) 1371; (c) D. Kost, I. Kalikhman, in: Z. Rappoport, Y. Apeloig (Eds.), The Chemistry of Organic Silicon Compounds, vol. 2, John Wiley and Sons Ltd., New York, 1998, p. 1339. [2] (a) D. Kost, I. Kalikhman, Advances in Organometallic Chemistry, in: R. West, A.F. Hill (Eds.), Elsevier, Amsterdam, 2004, p. 1; (b) D. Kost, V. Kingston, B. Gostevskii, A. Ellern, D. Stalke, B. Walfort, I. Kalikhman, Organometallics 21 (2002) 2293. [3] (a) R. Tacke, R. Bertermann, M. Penka, O. Seiler, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 629 (2003) 2415; (b) O. Seiler, R. Bertermann, N. Buggisch, C. Burschka, M. Penka, D. Tebbe, R. Tacke, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 629 (2003) 1403. [4] (a) J. Wagler, U. Bo¨hme, G. Roewer, Angewandte Chemie 114 (2002) 1825; J. Wagler, U. Bo¨hme, G. Roewer, Angewandte Chemie-International Edition in English 41 (2002) 1732; (b) J. Wagler, U. Bo¨hme, E. Brendler, G. Roewer, Zeitschrift fu¨r Naturforschung B 59 (2004) 1348; (c) J. Wagler, U. Bo¨hme, E. Brendler, S. Blaurock, G. Roewer, Zeitschrift fu¨r Anorganische und Allgemeine Chemie 631 (2005) 2907. [5] (a) M. Oestreich, Chemistry – A European Journal 12 (2006) 30; (b) S. Rendler, M. Oestreich Synthesis (2005) 1727. [6] (a) G. Pohnert, Angewandte Chemie 114 (2002) 3299; G. Pohnert, Angewandte Chemie-International Edition in English 41 (2002) 3167; (b) R. Tacke, Angewandte Chemie 111 (1999) 3197; R. Tacke, Angewandte Chemie-International Edition in English 38 (1999) 3015. [7] (a) R. Tacke, R. Bertermann, C. Burschka, S. Dragota, M. Penka, I. Richter, Journal of the American Chemical Society 126 (2004) 14493; (b) S. Dragota, R. Bertermann, C. Burschka, M. Penka, R. Tacke, Organometallics 24 (2005) 5560. [8] (a) R.J.P. Corriu, C. Gue´rin, J.J.E. Moreau, Topics in Stereochemistry 15 (1984) 43; (b) R.J.P. Corriu, C. Guerin, J.J.E. Moreau, in: S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic Silicon Compounds, 1, John Wiley and Sons Ltd., New York, 1989, p. 305; (c) P.J. Stang, A.E. Learned, Journal of Organic Chemistry 54 (1989) 1779; (d) A. Kawachi, H. Maeda, K. Mitsudo, K. Tamao, Organometallics 18 (1999) 4530; (e) M. Omote, T. Tokita, Y. Shimizu, I. Imae, E. Shirakawa, Y. Kawakami, Journal of Organometallic Chemistry 611 (2000) 20; (f) C. Strohmann, M. Bindl, V.C. Fraaß, J. Ho¨rnig, Angewandte Chemie 116 (2004) 1029; (g) C. Strohmann, M. Bindl, V.C. Fraaß, J. Ho¨rnig, Angewandte Chemie-International Edition 43 (2004) 1011.
U. Bo¨hme et al. / Inorganic Chemistry Communications 9 (2006) 806–809 [9] (a) T.H. Chan, P. Pellon, Journal of the American Chemical Society 111 (1989) 8737; (b) T.H. Chan, K.T. Nwe, Journal of Organic Chemistry 57 (1992) 6107; (c) C. Strohmann, B.C. Abele, K. Lehmen, D. Schildbach, Angewandte Chemie 117 (2005) 3196; (d) C. Strohmann, B.C. Abele, K. Lehmen, D. Schildbach, Angewandte Chemie-International Edition 44 (2005) 3136. [10] R. Fleischer, H. Wunderlich, M. Braun, European Journal of Organic Chemistry (1998) 1063. [11] Electronic supplementary information available: characterising data for all new complexes. [12] General procedure: Ligand 1a or 1b (6 mmol) and triethylamine (15 mmol) were placed in a Schlenk flask and 40 mL of DME added. Chlorosilane was added dropwise at 10 °C (6.2 mmol of dichlorodialkylsilane; 3 mmol of SiCl4, respectively). A white precipitate is formed immediately. The reaction mixture was stirred at room temperature for 2 h and at reflux temperature for 40 h. During that time the mixture became yellow to orange. The solvent was completely removed in vacuo and the residue was treated with nhexane. The insoluble triethylammonium chloride was filtered off, washed with n-hexane and the volume of the filtrate was reduced in vacuo. Storage overnight in the refrigerator yielded the product, which was separated by filtration and dried in vacuo. [13] Crystallographic data for 2a: chemical formula moiety C56H46N2O4Si, C0.80H2O0.40 (dimethoxyethane with 20% site occupation),
809
Mw = 857.06, Tetragonal, P43212, a = b = 11.422(2), c= ˚ a = b = c = 90°, V = 4992.5(14) A ˚ 3, Z = 4, qcalc = 1.140 38.270(8) A Mg/m3, reflections collected/unique 156180/4404 [Rint = 0.0430], refinement method full-matrix least-squares on F2, data/restraints/ parameters 4404/150/391, Final R indices [I > 2r(I)] R1 = 0.072, (all data) R1 = 0.081, absolute structure parameter 0.2(3). The absolute configuration of this structure was assigned according to the configuration of the chiral ligand, since the measured data do not allow unambiguous determination of the absolute structure. Data collected with a Bruker X8 APEX2 diffractometer. Intensities were collected with graphite monochromatised Mo Ka radiation at room temperature. The structure was solved by Direct methods, using the SHELXS program and refined by fullmatrix least-squares method using SHELX97. CCDC No. 271 516. [14] Crystallographic data for 3a: C26H29NO2Si, Mw = 415.59, Ortho˚, rhombic, P212121, a = 11.5450(3), b = 11.8641(3), c = 16.4953(4) A ˚ 3, Z = 4, qcalc = 1.222 Mg/m3, a = b = c = 90°, V = 2259.4(1) A Reflections collected/unique 38266/4199 [Rint = 0.0439], Data/ restraints/parameters 4199/0/275, Final R indices [I > 2r(I)] R1 = 0.028, (all data) R1 = 0.033, Absolute structure parameter 0.00(9). Data collected with a Bruker X8 APEX2 diffractometer. Intensities were collected with graphite monochromatised Mo Ka radiation at 180°C. The structure was solved by Direct methods, using the SHELXS program and refined by full-matrix least-squares method using SHELX97. CCDC No. 288 067.