Isomerization of a cationic (η5-C5Me5)Ir(III) complex involving remote C–C and C–H bond formation

The reactivity of an unsaturated, cationic (C5Me5)Ir(III) complex (2(Xyl)+) bearing the xylyl-substituted terphenyl phosphine PMe2ArXyl2 (ArXyl2 = C6H3-2,6-(C6H3-2,6-Me2)2) towards triethylamine (NEt3) is studied and compared to our previous investigations based on related 2(Dipp)+ containing bulkier PMe2ArDipp2 (ArDipp2 C6H3-2,6-(C6H3-2,6-iPr2)2). Low-temperature multinuclear NMR studies support formation a C–C bond between deprotonated C5Me5 ligand flanking xylyl ring phosphine, which becomes dearomatized (complex 4(Xyl)+). Interestingly, this presents divergent relative diisopropylphenyl counterpart, undergoing formal addition HCl yield 5(Xyl)+, isomeric starting 2(Xyl)+. These transformations are rationalized by means Density Functional Theory (DFT) calculations.