Barium as Honorary Transition Metal in Action: Experimental and Theoretical Study of Ba(CO)+ and Ba(CO)− |
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| Authors: | Xuan Wu Prof. Lili Zhao Dandan Jiang Dr. Israel Fernández Prof. Robert Berger Prof. Mingfei Zhou Prof. Gernot Frenking |
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| Affiliation: | 1. Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433 China;2. Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for, Advanced Materials, Nanjing Tech University, Nanjing, 211816 China;3. Departamento de Química Orgánica I and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040- Madrid, Spain;4. Fachbereich Chemie, Philipps-Universit?t Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany |
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| Abstract: | Ba(CO)+ and Ba(CO)? have been produced and isolated in a low‐temperature neon matrix. The observed C?O stretching wavenumber for Ba(CO)+ of 1911.2 cm?1 is the most red‐shifted value measured for any metal carbonyl cations, indicating strong π backdonation of electron density from Ba+ to CO. Quantum chemical calculations indicate that Ba(CO)+ has a 2Π reference state, which correlates with the 2D(5d1) excited state of Ba+ that comprises significant Ba+(5dπ1)→CO(π* LUMO) backbonding, letting the Ba(CO)+ complex behave like a conventional transition‐metal carbonyl. A bonding analysis shows that the π backdonation in Ba(CO)+ is much stronger than the Ba+(5dσ/6s)←CO(HOMO) σ donation. The Ba+ cation in the 2D(5d1) excited state is a donor rather than an acceptor. Covalent bonding in the radical anion Ba(CO)? takes place mainly through Ba(5dπ)←CO?(π* SOMO) π donation and Ba(5dσ/6s)←CO?(HOMO) σ donation. The most important valence functions at barium in Ba(CO)+ cation and Ba(CO)? anion are the 5d orbitals. |
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| Keywords: | barium bonding analysis carbonyl complexes matrix isolation organometallic chemistry |
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