Towards clustered carbonyl cations [M3(CO)14]2+ (M = Ru, Os): the need for innocent deelectronation

To access the hitherto almost unknown class of clustered transition metal carbonyl cations, the trimetal dodecacarbonyls M-3(CO)(12) (M = Ru, Os) were reacted with the oxidant Ag+[WCA](-), but yielded the silver complexes [Ag{M-3(CO)(12)}(2)](+)[WCA](-) (WCA = [Al(ORF)(4)](-), [F{Al(ORF)(3)}(2)](-); R-F = -OC(CF3)(3)). Addition of further diiodine I-2 to increase the redox potential led for M = Ru non-specifically to divalent mixed iodo-Ru-II-carbonyl cations. With [NO](+), even the N-O bond was cleaved and led to the butterfly carbonyl complex cation [Ru4N(CO)(13)](+) in low yield. Obviously, ionization of M-3(CO)(12) with retention of its pseudo-binary composition including only M and CO is difficult and the inorganic reagents did react non-innocently. Yet, the radical cation of the commercially available perhalogenated anthracene derivative 9,10-dichlorooctafluoroanthracene (anthracene(Hal)) is a straightforward accessible innocent deelectronator with a half-wave potential E-1/2 of 1.42 V vs. Fc(0/+). It deelectronates M-3(CO)(12) under a CO atmosphere and leads to the structurally characterized cluster salts [M-3(CO)(14)](2+)([WCA](-))(2) including a linear M-3 chain. The structural characterization as well as vibrational and NMR spectroscopies indicate the presence of three electronically independent sets of carbonyl ligands, which almost mimic M(CO)(5), free CO and even [M(CO)(6)](2+) in one and the same cation.