Synthesis and reactivity of some diselenasila cycles containing an annelated dicarba‐closo‐dodecaborane(12) unit

The use of 1,2‐diselenolato‐1,2‐dicarba‐closo‐dodecaborane(12) dianions [1,2‐(1,2‐C₂B₁₀H₁₀)Se₂]^2? prepared in situ as the dilithium salt may lead to irreproducible results. This is shown by the straightforward synthesis of silanes using the purified and isolated dianions, in contrast with previous less successful attempts. Thus, the reactions of the dianions with dichlorosilanes afford the five‐membered diselenasila cycles containing the SiMe₂ or the SiPh₂ units, and with 1,2‐dichloro‐tetramethyldisilane the six‐membered cycle containing the Si₂Me₄ unit. The latter was studied by X‐ray diffraction, and all products were characterized by multinuclear magnetic resonance (¹H, ¹³C, ²⁹Si, ⁷⁷Se NMR) in solution. Novel isotope effects were detected in ¹³C and ⁷⁷Se NMR spectra. Exchange reactions of the five‐ and six‐membered diselanasila cycles with chlorosilanes were studied. Copyright © 2009 John Wiley & Sons, Ltd.