Synthesis and characterization of [Rh7(CO)16X]2- anions (X=Br,I)

The reaction of Rh6(CO)16 with an excess of tetraalkylammonium halides in tetrahydrofuran gives the heptanuclear [Rh7(CO)16X]2- anions (X = Br, I), which have been isolated and characterised. The same anions were obtained by condensation of the Rh2(CO)4X2 carbonyl halides with the hexanuclear [Rh6(CO)15]2- anion, or by reaction of the [Rh7(CO)16]3- anion with iodine.