The synthesis, vibrational spectra, and molecular structure of [Ir(CO)(6)][SbF6](3)center dot 4HF - The first structurally characterized salt with a tripositive, homoleptic metal carbonyl cation and the first example of a tetrahedral hydrogen-bonded (HF)(

{The reductive carbonylation of IrF6 in a dilute solution of SbF5 in anhydrous HF (1:6 by volume) produces surprisingly at 25 degreesC and 1.5 atm CO the complex salt [Ir(CO)(6)][SbF6](3).4HF, while [Ir(CO)(6)][Sb2F11](3) is obtained in liquid SbF5 under similar conditions. Vibrational spectra in the CO stretching range for both salts and [Ir(CO)(6)](3+)((solv)) are identical within error limits, and v(CO)(av) is with 2269 cm(-1) the highest average stretching frequency so far observed for octahedral metal carbonyl cations. A vibrational assignment supported by DFT calculations is presented, and the vibrational fundamentals are compared to those of [OS(CO)(6)](2+). The molecular structure of [Ir(CO)(6)][SbF6](3).4HF is determined by single-crystal X-ray diffraction. Crystal data for [Ir(CO)(6)][SbF6](3).4HF: rhombohedral, R3c (No. 161)