1,1,2,2-Tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane: synthesis and spontaneous polymerization

Gas-phase dehalogenation of 1,2-bis[chloro(dimethyl)silyl]-2-trimethylsilylethane with alkali metals gave 1,1,2,2-tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane (3). Its spontaneous ring-opening polymerization at room temperature afforded an amorphous linear polymer with Tg = −8.9°C, Mw = 3.47·105–3.85·105, and Mw/Mn = 2.43—2.86. According to spectroscopic data (IR and 1H, 13C, and 29Si NMR), the backbone of the polymer consists of alternating monomer units joined in the “head-to-tail” ([Me2SiCH(SiMe3)CH2SiMe2SiMe2CH-(SiMe3)CH2SiMe2]) and “head-to-head” ways ([Me2SiCH2CH(SiMe3)SiMe2SiMe2CH-(SiMe3)CH2SiMe2]).