Vibrational Spectroscopy of Intermediates in Methane-to-Methanol Conversion by FeO⁺

Abstract

Gas phase FeO(+) can convert methane to methanol under thermal conditions. Two key intermediates of this reaction are the [HO-Fe-CH(3)](+) insertion intermediate and Fe(+)(CH(3)OH) exit channel complex. These intermediates are selectively formed by reaction of laser-ablated Fe(+) with organic precursors under specific source conditions and are cooled in a supersonic expansion. Vibrational spectra of the sextet and quartet states of the intermediates in the O-H and C-H stretching regions are measured by infrared multiple photon dissociation of Fe(+)(CH(3)OH) and [HO-Fe-CH(3)](+) and by monitoring argon atom loss following irradiation of Fe(+)(CH(3)OH)(Ar) and [HO-Fe-CH(3)](+)(Ar)(n) (n = 1, 2). Analysis of the experimental results is aided by comparison with hybrid density functional theory computed frequencies. Also, an improved potential energy surface for the FeO(+) + CH(4) reaction is developed based on CCSD(T) and CBS-QB3 calculations for the reactants, intermediates, transition states, and products.

Vibrational spectroscopy of intermediates in benzene-to-pheno conversion by FeO+

“…Our group has studied the vibrational and electronic spectroscopy of intermediates of methane to methanol conversion by FeO ϩ [15,16]. By extending these studies to benzene-phenol conversion by FeO ate the effect of the aromatic ring on the reaction mechanism.…”

“…In our study of the insertion intermediate for the FeO ϩ ϩ CH 4 reaction, we also found that both spin states contribute to the vibrational spectrum. IRMPD of [HO-Fe-CH 3 ] ϩ gives an asymmetrical peak at 3623 cm Ϫ1 with a shoulder at 3576 cm Ϫ1 , which were assigned to the sextet and quartet states, respectively [15]. Adding argon atoms to [HO-Fe-CH 3 ] ϩ removes charge from the metal center and leads to progressively larger blue shifts in the O-H stretch frequencies.…”

Related Properties to Acidity and Basicity From Computational Chemistry Approach

“…17,18 É importante ressaltar que os resultados obtidos foram para fase gás e nenhuma relação pode ser estabelecida com dados experimentais obtidos em fase condensada devido à influência do efeito do solvente nos resultados obtidos.…”

“…15 A partir da geometria otimizada, foi realizado novo cálculo de otimização, além do cálculo de frequência e propriedades termodinâmicas das correspondentes moléculas usando o método CBS-QB3, 16 cujos cálculos de propriedades termodinâmicas são comparáveis aos valores experimentais, além de ser usado para cálculos de metais de transição na forma iônica e cálculos de pKa. 17,18 É importante ressaltar que os resultados obtidos foram para fase gás e nenhuma relação pode ser estabelecida com dados experimentais obtidos em fase condensada devido à influência do efeito do solvente nos resultados obtidos. 6 +2 obtidos por meio da difração de raios-X, por cálculos computacionais em que a otimização foi feita inicialmente pelo nível de teoria B3LYP/6-311G++(2d,2p), seguida da otimização pelo método CBS-QB3, ou seja, B3LYP/6-311G++(2d,2p)//CBS-QB3.…”

Über die Rolle von [CuO]+ bei spinselektiven Wasserstoff‐ und Sauerstoff‐Übertragungen in der Aktivierung von Methan

“…Eine vollständige Beschreibung der [FeO] + -vermittelten Umwandlung von Methan zu Methanol gelang dabei erst kürzlich durch die Anwendung moderner Gasphasenspektroskopie in Kombination mit verlässlichen Molekülrechnungen. [11] Für Kupfersysteme ist der Stand der Forschung weniger weit fortgeschritten. Während die Natur des aktiven Zentrums der pMMO lange Gegenstand heftiger Diskussionen war, [3,4,12] wurde für [CuO] + bereits vor zehn Jahren ein hohes Potenzial für die Umwandlung von Methan zu Methanol vorausgesagt; [13,14] einen experimentellen Beweis dafür gab es jedoch bisher noch nicht.…”