The First Triple‐Decker Complex with a Carbenium Center, [CpCo(μ‐C3B2Me5)RuC5Me4CH2]+: Synthesis, Reactivity, X‐Ray Structure, and Bonding

The first derivative of the methylium cation with the triple‐decker substituent, [CpCo(C3B2Me5)RuC5Me4CH2]PF6 (2PF6), was synthesized from the reaction of the triple‐decker complex CpCo(C3B2Me5)RuCp* (1) with the salt of the trityl cation [CPh3]+. The X‐ray crystal structure of 2PF6 reveals that the methylium carbon is bound to the ruthenium with Ru−C bond length of 2.259 Å and corresponds to the description of its structure as η6‐fulvene‐ruthenium. Reactions of 2PF6 with nucleophiles OH−, Ph3P, Et3N led to the corresponding derivatives of 1 in high yields. Aromatic amines PhNEt2 and 4‐MeC6H4NH2 react with 2PF6 to give the electrophilic aromatic substitution products quantitatively. Chemical reduction of 2PF6 with Zn powder in tetrahydrofuran leads to the formation of the bis(triple‐decker) derivative (CpCo(C3B2Me5)RuC5Me4CH2)2 (10) with a CH2CH2‐bridge. The structures of complexes 4, 7–10 were determined by X‐ray diffraction. Density functional calculations support the crystallographically determined geometry of 2 and allow rationalization of some characteristics of its structure, spectroscopy, and reactivity. Triple‐decker sandwich: The first example of the methylium cation with a triple‐decker substituent, [CpCo(C3B2Me5)RuC5Me4CH2]+, has been synthesized. Its reactivity allows selective and efficient post‐synthetic modification of the triple‐decker complexes which otherwise would be inaccessible or challenging to synthesize.