The quest for stable σ-methane complexes: computational and experimental studies

Characterisation of Alkane σ‐Complexes

“…Such studies have proven successful in supporting the results of experimental observations;30, 54, 74, 84, 110 however, the ability of theoretical calculations to predict experimentally observable alkane complexes has been less reliable. For example, theoretical results prompted Brookhart to unsuccessfully attempt protonation of the cationic palladium complex, [Pd(PONOP)Me][BAr F 4 ], to form the dicationic methane complex, [Pd(PONOP)(CH 4 )][BAr F 4 ] 2 ,112 and conversely, a study comparing methane adducts of “TpRe” and “CpRe” fragments, was prognostic of the thermodynamic stabilising effects of the Tp ligand (later verified experimentally by Duckett and George83—see above) 108. Disconcertingly, the results of independent studies of similar or even identical systems often differ greatly 112.…”

“…For example, theoretical results prompted Brookhart to unsuccessfully attempt protonation of the cationic palladium complex, [Pd(PONOP)Me][BAr F 4 ], to form the dicationic methane complex, [Pd(PONOP)(CH 4 )][BAr F 4 ] 2 ,112 and conversely, a study comparing methane adducts of “TpRe” and “CpRe” fragments, was prognostic of the thermodynamic stabilising effects of the Tp ligand (later verified experimentally by Duckett and George83—see above) 108. Disconcertingly, the results of independent studies of similar or even identical systems often differ greatly 112. 113 As such, although theoretical studies promote a cost‐effective means to study alkane σ‐complexes, the strength of this method would seem to be in explaining experimentally observed phenomenon rather than predicting the character of previously unobserved complexes.…”

Contrasting electronic requirements for CH binding and CH activation in d6 half‐sandwich complexes of rhenium and tungsten

“…Many, if not most of the excellent experimental studies have benefitted greatly from the synergy arising from computational studies . The latter provides insight into the process, that cannot be obtained from experiments.…”

Shilov alkane platinum chemistry: 45 years

“…Calculations show [39,40] that the Ir III. CH 4 complex in this case is only 5 kcal mol -1 higher on the energy scale than the ground state of the H-Ir-CH 3 species.…”