Salts of the Cobalt( I ) Complexes [Co(CO) 5 ] + and [Co(CO) 2 (NO) 2 ] + and the Lewis Acid–Base Adduct [Co 2 (CO) 7 COB(CF 3 ) 3 ]

The reaction of [Co 2 (CO) 8 ] with (CF 3 ) 3 BCO in hexane leads to the Lewis acid–base adduct [Co 2 (CO) 7 COB(CF 3 ) 3 ] in high yield. When the reaction is performed in anhydrous HF solution [Co(CO) 5 ][(CF 3 ) 3 BF] is isolated. The product contains the first example of a homoleptic metal pentacarbonyl cation with 18 valence electrons and a trigonal‐bipyramidal structure. Treatment of [Co 2 (CO) 8 ] or [Co(CO) 3 NO] with NO + salts of weakly coordinating anions results in mixed crystals containing the [Co(CO) 5 ] + /[Co(CO) 2 (NO) 2 ] + ions or pure novel [Co(CO) 2 (NO) 2 ] + salts, respectively. This is a promising route to other new metal carbonyl nitrosyl cations or even homoleptic metal nitrosyl cations. All compounds were characterized by vibrational spectroscopy and by single‐crystal X‐ray diffraction.