Synthesis and characterization of variously asymmetrically chloro-substituted disilanes and trisilanes – A new perspective on known compounds

• Presentation of a redesigned pathway to asymmetrically chloro(alkyl)di- and trisilanes.
• High selectivity since corresponding phenyl-substituted alkylsilanes serve as precursors.
• Simplified preparative handling compared to already published synthesis methods.
• DSC data reveal a plastically crystalline phase for chloro(methyl)disilanes of spherical shape.
• CV experiments show reduction peaks for chloro(alkyl)silanes at highly negative potentials.

Asymmetrically phenyl-substituted disilanes of the general formula RMe2Si–SiMePh2 (MPD02: R = Me, MPD12: R = Ph) and the trisilane (PhMe2Si)2SiMePh (MPT111) were prepared from the corresponding monosilanes using lithium as coupling reagent. These compounds were utilized as precursors for the preparation of the chlorosilanes Cl2MeSi–SiMe2R (CMD20: R = Me; CMD21: R = Cl) and (ClMe2Si)2SiMeCl (CMT111). The phenyl groups were selectively removed using acetyl chloride and anhydrous AlCl3. Subjecting these phenyl-substituted methyloligosilanes to the redesigned literature-known reaction conditions, the strengths of the synthetic routes shown so far were combined. In addition, not only methyl-substituents are applicable, since we used Ph2(tBu)Si–SiMe2Ph (tBuMPD21) as precursor for the preparation of Cl2(tBu)Si–SiMe2Cl (tBuCMD21). The characterization of the phenyl- and chloro-substituted di- and trisilanes mentioned above is not completely reported in literature. They were fully analyzed by means of NMR and IR spectroscopy, GC–MS, DSC and elemental analysis at our chair. DSC studies of the synthesized chlorosilanes led to the assumption of a plastic crystalline behavior for certain compounds. Beyond that, CV measurements of the chloro-substituted compounds pointed out that their reduction occurs at highly negative potentials.

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