Communication
Pentacoordination of Silicon by Five Different Ligand Atoms: Neutral Silicon(IV) Complexes with SiClSONC and SiISONC Skeletons
Stefan Metz Dipl.-Chem.,
Christian Burschka Dr.,
Daniela Platte,
Reinhold Tacke Prof. Dr.,
Stefan Metz Dipl.-Chem.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorChristian Burschka Dr.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorDaniela Platte
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorReinhold Tacke Prof. Dr.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorStefan Metz Dipl.-Chem.,
Christian Burschka Dr.,
Daniela Platte,
Reinhold Tacke Prof. Dr.,
Stefan Metz Dipl.-Chem.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorChristian Burschka Dr.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorDaniela Platte
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorReinhold Tacke Prof. Dr.
Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany, Fax: (+49) 931-888-4609
Search for more papers by this authorGraphical Abstract
Take five: Pentacoordinate silicon with five different ligand atoms (SiClSONC and SiISONC skeletons) has been realized with the synthesis of the neutral silicon(IV) compound 1 and its iodo analogue, both of which exist in the solid state and in solution. The chloro ligand of 1 can be easily replaced to give further pentacoordinate silicon compounds.
References
- 1Selected reviews dealing with higher coordinate silicon compounds:
- 1aR. R. Holmes, Chem. Rev. 1996, 96, 927–950;
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- 5Based on solution NMR studies, the existence of 1-iodosilatrane has been claimed; however, the crystal structure and solid-state NMR data have not been reported: M. G. Voronkov, L. P. Petukhov, V. I. Rakhlin, V. P. Baryshok, B. Z. Shterenberg, R. G. Mirskov, V. A. Pestunovich, Izv. Akad. Nauk SSSR Ser. Khim. 1981, 2412; Bull. Acad. Sci. USSR Div. Chem. Sci. (Engl. Transl.) 1981, 30, 1991.
- 6In general, formally higher coordinate silicon(IV) complexes with SiI bonds are characterized by only weak Si⋅⋅⋅I interactions in solution and in the solid state, and are therefore best described as compounds consisting of cationic silicon species and iodide anions:
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- 7R. V. Singh, J. P. Tandon, Synth. React. Inorg. Met.-Org. Chem. 1981, 11, 109–131.
- 8Crystal structure analyses of 1–3: Suitable single crystals were mounted in inert oil (perfluoroalkyl ether, ABCR) on a glass fiber and then transferred to the cold nitrogen gas stream of the diffractometer (Bruker Nonius KAPPA APEX II (1; Goebel-mirror, MoKα radiation, λ=0.71073 Å) and Stoe IPDS (2 and 3; graphite-monochromated MoKα radiation, λ=0.71073 Å). All structures were solved by direct methods (SHELXS-97) and refined by full-matrix least-squares methods on F2 for all unique reflections (SHELXL-97). For the CH hydrogen atoms, a riding model was employed. CCDC 645425 (1), 645426 (2), and 645427 (3) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam. ac.uk/data_request/cif. Selected data for 1: single crystal of dimensions 0.2×0.2×0.1 mm obtained by slow cooling of a solution in acetonitrile from 80 to 20 °C, C17H16ClNOSSi, Mr=345.91, analysis at 100(2) K, monoclinic, space group P21/c (no. 14), a=10.9156(3), b=8.5881(3), c=17.0088(5) Å, β=94.983(2)°, V=1588.45(8) Å3, Z=4, ρcalcd=1.446 g cm−3, μ=0.448 mm−1, F(000)=720, 2 θmax=56.58°, 33 421 collected reflections, 3951 unique reflections (Rint=0.0393), 201 parameters, S=1.039, R1=0.0244 (I>2 σ(I)), wR2(all data)=0.0672, max./min. residual electron density +0.382/−0.288 e Å−3. Selected data for 2: single crystal of dimensions 0.5×0.2×0.1 mm obtained directly from the reaction mixture, C17H16INOSSi, Mr=437.36, analysis at 173(2) K, orthorhombic, space group Pbca (no. 61), a=8.7076(17), b=17.959(4), c=21.697(4) Å, V=3393.1(12) Å3, Z=8, ρcalcd=1.712 g cm−3, μ=2.082 mm−1, F(000)=1728, 2 θmax=56.24°, 21 542 collected reflections, 4089 unique reflections (Rint=0.0473), 201 parameters, S=1.026, R1=0.0301 (I>2 σ(I)), wR2 (all data)=0.0691, max./min. residual electron density +0.770/−0.544 e Å−3. Selected data for 3: single crystal of dimensions 0.5×0.4×0.2 mm obtained by slow cooling of a solution in dichloromethane from 20 to 4 °C, C18H16F3NO4S2Si, Mr=459.53, analysis at 173(2) K, monoclinic, space group P21/n (no. 14), a=11.669(2), b=12.247(2), c=13.865(3) Å, β=102.47(3)°, V=1934.7(7) Å3, Z=4, ρcalcd=1.578 g cm−3, μ=0.392 mm−1, F(000)=944, 2 θmax=56.44°, 14 216 collected reflections, 4699 unique reflections (Rint=0.0494), 264 parameters, S=1.037, R1=0.0412 (I>2 σ(I)), wR2 (all data)=0.0988, max./min. residual electron density +0.539/−0.326 e Å−3.
- 9NMR studies on 1–3: The solution 1H, 13C, 19F, and 29Si NMR spectra were recorded at 23 °C on a Bruker Avance 500 NMR spectrometer (1H, 500.1 MHz; 13C, 125.8 MHz; 29Si, 99.4 MHz) or a Bruker Avance 400 NMR spectrometer (1H, 400.1 MHz; 13C, 100.6 MHz; 19F, 376.5 MHz; 29Si, 79.5 MHz). CD2Cl2 was used as the solvent. Chemical shifts were determined relative to internal CDHCl2 (1H, δ=5.32 ppm), internal CD2Cl2 (13C, δ=53.8 ppm), external CFCl3 (19F, δ=0 ppm), or external TMS (29Si, δ=0 ppm). Assignment of the 13C NMR data was supported by DEPT135 experiments. Solid-state 13C, 15N, and 29Si VACP/MAS spectra were recorded at 22 °C on a Bruker DSX-400 NMR spectrometer with bottom layer rotors of ZrO2 (diameter, 7 mm) containing about 300 mg of sample (13C, 100.6 MHz; 15N, 40.6 MHz; 29Si, 79.5 MHz; external standard, TMS (13C, 29Si; δ=0 ppm) or glycine (15N, δ=−342.0 ppm); contact time, 1 ms (13C), 3 ms (15N), or 5 ms (29Si); 90° 1H transmitter pulse length, 3.6 μs; repetition time, 4 s).
- 10U. H. Berlekamp, A. Mix, B. Neumann, H.-G. Stammler, P. Jutzi, J. Organomet. Chem. 2003, 667, 167–175.
- 11Covalent radii [Å]: C, 0.73; N, 0.70 (0.75); O, 0.66 (0.73); Si, 1.17; S, 1.04; Cl, 0.99; I, 1.33. Data taken from: Holleman-Wiberg, Lehrbuch der Anorganischen Chemie, 101st ed., Walter de Gruyter, Berlin, 1995, p. 136.
- 12
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- 12cG. Fischer, V. Huch, P. Mayer, S. K. Vasisht, M. Veith, N. Wiberg, Angew. Chem. 2005, 117, 8096–8099; Angew. Chem. Int. Ed. 2005, 44, 7884–7887.
- 13Owing to 29Si,X (X=35Cl, 37Cl) coupling, the resonance signal in the 29Si VACP/MAS NMR spectrum of 1 is broad, with three maxima (δ=−82.2, −83.0, −83.7 ppm) of different intensities. Due to 29Si,127I coupling, the resonance signal in the 29Si VACP/MAS NMR spectrum of 2 is very broad (FWHH≈380 Hz).
- 14Compound 3 was barely soluble or unstable in most common organic solvents. In CD2Cl2 the solubility was sufficient for NMR measurements, but many scans were necessary. Because of the sensitivity of 3 in solution, a freshly prepared sample was used for each measurement (1H, 13C, 19F, 29Si).
- 15Due to the poor solubility of 2 in CD3CN at 23 °C, the NMR experiments were performed at 60 °C.
- 16The signal for the CF3 moiety could not be detected in the 13C NMR spectrum.
