Designer Mg-Mg and Zn-Zn Single Bonds Facilitated by Double Aromaticity in the M2B7-(M=Mg,Zn) Clusters

The simple homodinuclear M

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M single bonds for group II and XII elements are difficult to obtain as a result of the fulfilled s

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electronic configurations, consequently, a dicationic prototype is often utilized to design the M

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M

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single bond. Existing studies generally use sterically bulky organic ligands L

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to synthesize the compounds in the L

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M

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M

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L

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manner. However, here we report the design of Mg

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Mg and Zn

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Zn single bonds in two ligandless clusters, Mg

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B

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and Zn

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B

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, using density functional theory methods. The global minima of both of the clusters are in the form of M

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(B

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), where the M

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M single bonds are positioned above a quasi-planar hexagonal B

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moiety. Chemical bonding analyses further confirm the existence of Mg

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Mg and Zn

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Zn single bonds in these clusters, which are driven by the unusually stable B

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moiety that is both

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and

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aromatic. Vertical detachment energies of Mg

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B

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and Zn

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B

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are calculated to be 2.79 eV and 2.94 eV, respectively, for the future comparisons with experimental data.