A 13C nuclear magnetic resonance study of cyclobutadieneirontricarbonyl-substituted carbonium ions

(Cyclobutadiene)iron TricarbonylA Case of Theory before Experiment

“…A later 13 C NMR study of the alcohols (C 4 H 3 CH 2 OH)Fe(CO) 3 and (C 4 H 3 CH(OH)R)Fe(CO) 3 (R = CH 3 , C 6 H 5 ) in CDCl 3 and of the derived carbenium ions [(C 4 H 3 CH 2 )Fe(CO) 3 ] + and [(C 4 H 3 CHR)Fe(CO) 3 ] + (R = CH 3 , C 6 H 5 ) in concentrated H 2 SO 4 gave results which also were interpreted in terms of stabilization of the carbenium center via the interaction shown in formula 48 …”

Radical Stabilizing Ability of the Ferrocenyl and Cyclobutadieneiron Tricarbonyl Groups

“…Attention was next turned to the cyclobutadiene Fe(CO) 3 complexed radical 7 . Although this group is a good carbocation stabilizer, we are aware of no studies on the ability of cyclobutadiene iron tricarbonyl group to stabilize radicals. Shown in Figure are two views of the B3LYP/LANL2DZ-optimized structure of radical 7 .…”

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

“…Recently, there has been a modest, but significant resurgence of interest in the reactivity of derivatives of CBIT. CBIT-stabilized cation 1 has recently been studied extensively by the Snapper group, who have demonstrated the synthetic utility of this interesting intermediate, which reacts as an electrophilic partner in a variety of transformations. These reactions have been used to append olefinic substituents to CBIT, allowing for the syntheses of a wide variety of novel polycyclic systems through intramolecular Diels−Alder reactions, which in turn have proven to be useful precursors to interesting ring systems found in natural products 5e…”