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The heteronuclear group 14 M-iron tetracarbonyl clusters MFe(CO)4− (M = Si, Ge, Sn) anions have been generated in the gas phase by laser ablation of M–Fe alloys and detected by mass and photoelectron spectroscopy. With the support of quantum chemical calculations, the geometric and electronic structures of MFe(CO)4− (M = Si, Ge, Sn) are elucidated, which shows that all the MFe(CO)4− clusters have the M–Fe bonded, iron-centered, and carbonyl-terminal M–Fe(CO)4 structure with the C2v symmetry and a 2B2 ground state. The M–Fe bond can be considered a double bond, which includes one σ electron sharing bond and one π dative bond. The C–O bonds in those anionic clusters are calculated to be elongated to different extents, and in particular, the C–O bonds in SiFe(CO)4− are elongated more. The Si–Fe alloy thus turns out to be a better collocation to activate the C–O bonds in the gas phase among group 14. The present findings have important implications for the rational development of high-performance catalysts with isolated metal atoms/clusters dispersed on supports. [ABSTRACT FROM AUTHOR]

This work reports the observation and characterization of heterobinuclear transition-metal main-group metal oxide carbonyl complex anions, RuGeO(CO) n - ( n = 3-5), by combining mass-selected photoelectron velocity map imaging spectroscopy and quantum chemistry calculations. The experimentally determined vertical electron detachment energy of RuGeO(CO) 3 - surpasses those of RuGeO(CO) 4 - and RuGeO(CO) 5 - , which is attributed to distinctive bonding features. RuGeO(CO) 3 - manifests one covalent σ and two Ru-to-Ge dative π bonds, contrasting with the sole covalent σ bond present in RuGeO(CO) 4 - and RuGeO(CO) 5 - . Unpaired spin density distribution analysis reveals a 17-electron configuration at the Ru center in RuGeO(CO) 3 - and an 18-electron configuration in RuGeO(CO) 4 - and RuGeO(CO) 5 - . This work closes a gap in the quantitative physicochemical characterization of heteronuclear oxide carbonyl complexes, enhancing our insights into catalytic processes of CO/GeO on the metal surface at the molecular level.

Nitrogen fixation is confronted with great challenges in the field of chemistry. Herein, we report that single metal carbides PtC n - and PtC n N 2 - ( n = 4-6) are indispensable intermediates in the process of nitrogen fixation by mass spectrometry coupled with anionic photoelectron spectroscopy, quantum chemical calculations, and simulated density-of-state spectra. The most stable isomers of these cluster anions are characterized to have linear chain structures. The fixation and activation of dinitrogen are facilitated by the charge transfer from Pt and C n to N 2 . The significance of π back-donation of the 5d orbital of the Pt atom to the antibonding π orbits of N 2 for dinitrogen fixation and activation is discussed in detail. This study not only provides a theoretical basis at the molecular level for the activation of dinitrogen by mononuclear metal carbide clusters but also provides a new paradigm for dinitrogen fixation.