Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Sep 19;61(37):14742-14751.
doi: 10.1021/acs.inorgchem.2c02112. Epub 2022 Sep 1.

Synthesis and Characterization of Methoxylated Oligosilyl Group 4 Metallocenes

Aileen Sauermoser  1 , Thomas Lainer  1 , Gabriel Glotz  2 , Frank Czerny  3 , Bettina Schweda  4 , Roland C Fischer  1 , Michael Haas  1
Affiliations

Synthesis and Characterization of Methoxylated Oligosilyl Group 4 Metallocenes

Aileen Sauermoser et al. Inorg Chem. .

Abstract

New methoxylated oligosilyl-substituted metallocenes were synthesized by the reaction of two oligosilanides with different metallocene dichlorides (M = Ti, Zr, and Hf). The first investigated tris(trimethoxysilyl)silanide [(MeO)3Si]3SiK (1) underwent a selective monosubstitution to the respective oligosilyl-decorated metallocenes [(MeO)3Si]3SiMClCp2 (2-4). Surprisingly, the attempted disilylation with this silanide was not possible. However, in the case of titanocene dichloride, a stable radical [(MeO)3Si]3SiTiCp2 (5) was formed. The unsuccessful isolation of bisilylated metallocenes encouraged us to investigate the reactivity of another silanide. Therefore, we synthesized a hitherto unknown disilanide K[(MeO)3Si]2Si(SiMe2)2Si[(MeO)3Si]2K (8), which was accessible in good yields. The reaction of compound 8 and different metallocene dichlorides (M = Ti, Zr, and Hf) gave rise to the formation of heterocyclic compounds 9-11 in good yields.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interest.

Figures

Chart 1
Chart 1. Reported Silyl-Substituted Titanocenes
Chart 2
Chart 2. Reported Silyl-Substituted Zirconocenes and Hafnocenes (M = Zr and Hf)
Scheme 1
Scheme 1. Reaction of Dodecamethoxyneopentasilane with Suitable Bases Forming 1a–c
Scheme 2
Scheme 2. Reaction of 1c with Cl2MCp2 (M = Ti, Zr, Hf) to Synthesize the Oligosilyl-Substituted Metallocenes 2–4
Figure 1
Figure 1
Oak Ridge thermal-ellipsoid plot (ORTEP) for compound 2. Thermal ellipsoids are depicted at the 50% probability level. Hydrogen atoms are omitted and carbon atoms are wireframed for clarity. Selected bond lengths (Å) and bond angles (deg) with estimated standard deviations: Ti(1)–Cl(1) 2.3388(7), Ti(1)–Si(1) 2.7037(7), Si(1)–Si(2) 2.3449(9), Si(1)–Si(3) 2.3589(8), Si(1)–Si(4) 2.3485(9), Cl(1)–Ti(1)–Si(1) 94.40(3), Si(2)Si(1)–Si(4) 104.50(3), Si(2)–Si(1)–Si(3) 105.61(3), Si(4)–Si(1)–Si(3) 101.98(3), Si(2)–Si(1)–Ti(1) 109.43(3), Si(4)–Si(1)–Ti(1) 116.42(3), Si(3)–Si(1)–Ti(1) 117.61(3).
Scheme 3
Scheme 3. Reaction of 1c with 0.5 equiv of Cl2TiCp2
Figure 2
Figure 2
ORTEP for compound 5. Thermal ellipsoids are depicted at the 50% probability level. Hydrogen atoms are omitted and carbon atoms are wireframed for clarity. Selected bond lengths (Å) and bond angles (deg) with estimated standard deviations: Ti(1)–O(1) 2.2150(17), Ti(1)–Si(1) 2.7432(7), Si(1)–Si(2) 2.3133(10), Si(1)–Si(3) 2.3322(10), Si(1)–Si(4) 2.3319(11), O(1)–Ti(1)–Si(1) 73.61(4), Si(2)–Si(1)–Si(4) 109.21 (4), Si(2)–Si(1)–Si(3) 100.95, Si(4)–Si(1)–Si(3) 104.42(4), Si(2)–Si(1)–Ti(1) 78.75(3), Si(4)–Si(1)–Ti(1) 129.92(4), Si(3)–Si(1)–Ti(1) 122.97(4).
Figure 3
Figure 3
Experimental (black line) and simulated (red line) X-band EPR spectra of 5 at 280 K in C6D6, and the inset presents the experimental spectrum with increased instrument gain to better visualize small intensity signals.
Scheme 4
Scheme 4. Reduction of 2 with KC8 or [{(MesNacnac)Mg}2] (MesNacnac = [(MesNCMe)2CH]−, Mes = Mesityl)
Scheme 5
Scheme 5. Reaction of 5 with TEMPO or (Bromomethyl)benzene to Form Compounds 6 and 7
Scheme 6
Scheme 6. Reaction of 1,1,1,6,6,6-Hexamethoxy-3,3,4,4-tetramethyl-2,2,5,5-tetrakis-(trimethoxysilyl)hexasilane with 2 equiv of KOtBu to the Respective Dianion 8(34)
Figure 4
Figure 4
ORTEP for compound 8 stabilized by 18-crown-6. Thermal ellipsoids are depicted at the 50% probability level. Hydrogen atoms are omitted and carbon atoms are wireframed for clarity. Selected bond lengths (Å) and bond angles (deg) with estimated standard deviations: K(1)–O(1) 2.941(2), K(1)–O(2) 3.289(2), K(1)–O(3) 3.040(11), O(1)–Si(2) 1.660(3), Si(2)–O(2) 1.670(2), Si(2)–O(3) 1.662(5), Si(1)–Si(2) 2.3023(14), Si(1)–Si(3) 2.3100(12), Si(1)–Si(4) 2.3568(12), O(1)–K(1)–Si(2) 26.87(5), O(2)–K(1)–Si(2) 27.47(4), O(3)–K(1)–Si(2) 27.20(8), O(1)–K(1)–O(2) 47.74(5), O(1)–K(1)–O(3) 43.54(10), O(3)–K(1)–O(2) 48.26(10), Si(2)–Si(1)–Si(3) 102.24(5), Si(2)–Si(1)–Si(4) 105.83(5), Si(3)–Si(1)–Si(4) 103.32(4).
Scheme 7
Scheme 7. Reaction of 8 with Cl2MCp2 (M = Ti, Zr, Hf) to the Heterocyclic Compounds 9–11
Figure 5
Figure 5
ORTEP for compound 9. Thermal ellipsoids are depicted at the 50% probability level. Hydrogen atoms are omitted and carbon atoms are wireframed for clarity. Selected bond lengths (Å) and bond angles (deg) with estimated standard deviations: Ti(1)–Si(1) 2.6697(9), Ti(1)–Si(4) 2.6884(9), Si(1)–Si(2) 2.3624(11), Si(1)–Si(5) 2.3261(11), Si(1)–Si(6) 2.3355(11), Si(2)–Si(3) 2.3531(11), Si(3)–Si(4) 2.3755(10), Si(4)–Si(8) 2.3399(11), Si(4)–Si(7) 2.3282(11), Si(1)–Ti(1)–Si(4) 84.63(3), Si(2)–Si(1)–Ti(1) 111.29(3), Si(5)–Si(1)–Ti(1) 110.85(4), Si(6)–Si(1)–Ti(1) 120.12(4), Si(3)-Si(4)–Ti(1) 112.80(4), Si(8)–Si(4)–Ti(1) 120.90(4), Si(7)–Si(4)–Ti(1) 109.49(4), Si(5), Si(1), Si(2) 109.84(4), Si(5)–Si(1)–Si(6) 103.98(4), Si(6)–Si(1)–Si(2) 99.95(4), Si(3)–Si(2)–Si(1) 103.92(4), Si(2)–Si(3)–Si(4) 106.11(4), Si(8)–Si(4)–Si(3) 108.11(4), Si(7)–Si(4)–Si(3) 107.40(4), Si(7)–Si(4)–Si(8) 96.31(4).
Figure 6
Figure 6
UV–vis spectra of compounds 2–4 (a) and 9–11 (b) (c = 1 × 10–3 mol/L; solvent: n-hexane).
Figure 7
Figure 7
LUMO (left) and HOMO (right) of compounds 2 (above) and 9 (below).
See this image and copyright information in PMC

References

    1. Tilley T. D. The coordination polymerization of silanes to polysilanes by a ″sigma.-bond metathesis″ mechanism. Implications for linear chain growth. Acc. Chem. Res. 1993, 26, 22–29. 10.1021/ar00025a004. - DOI
    1. Gauvin F.; Harrod J. F.; Woo H. G.. Catalytic Dehydrocoupling: A General Strategy for the Formation of Element–Element Bonds. In Advances in Organometallic Chemistry, 42nd ed.; Elsevier, 1998; pp 363–405.
    1. Reichl J. A.; Berry D. H.. Recent Progress in Transition Metal-Catalyzed Reactions of Silicon, Germanium, and Tin. In Advances in Organometallic Chemistry; Elsevier, 1999; pp 197–265.
    1. Corey J. Y.Dehydrocoupling of Hydrosilanes to Polysilanes and Silicon Oligomers: A 30 Year Overview. In Advances in Organometallic Chemistry, 51st ed.; Elsevier, 2004; pp 1–52.
    1. Aitken C.; Harrod J. F.; Samuel E. Polymerization of primary silanes to linear polysilanes catalyzed by titanocene derivatives. J. Organomet. Chem. 1985, 279, C11–C13. 10.1016/0022-328X(85)87029-7. - DOI