Pseudohalonium ions: [Me3Si-X-SiMe3]+ (X=CN, OCN, SCN, and NNN).

By utilizing reaction mixtures, such as Me(3)Si-X/[Me(3)Si-X-SiMe(3)](+) (X=CN, OCN, SCN, and NNN), it was possible to prepare the first examples of bissilylated pseudohalonium cations in high yields. The structure and bonding of a whole series of salts containing pseudohalonium cations is discussed on the basis of experimentally observed (X-ray diffraction, Raman, and IR spectroscopy, and mass spectrometry) and theoretically obtained data. Salts containing pseudohalonium cations are only stable in the presence of weakly coordinating anions, such as the well-known tetrakis(pentafluorophenyl)borate, [B(C(6)F(5))(4)](-).