Bis(tri-<i>tert</i>-butylsilyl)silylene: Triplet Ground State Silylene

Upon irradiation with λ = 254 nm light over the temperature range of 9−80 K, methylcyclohexane glass matrixes of 1a and 1b gave a characteristic broad EPR signal at 845 mT (X-band, 9.4 GHz) due to bis(tri-tert-butylsilyl)silylene, (tBu3Si)2Si: (2). The signal intensity as a function of temperature (9−80 K) gave a linear relation, and the spin multiplicity of 2 in the ground state was established to be a triplet. Product analysis, from which disilacyclobutane derivative 3 and dihydrosilane (tBu3Si)2SiH2 (4) were formed, also supports the conclusion about the multiplicity of 2.