Evolution of structures and stabilities of zinc-doped tin clusters SnnZn, n = 1-12. Three-dimensional aromaticity of the magic clusters Sn10Zn and Sn12Zn

Graphical abstract: Both Sn12Zn and Sn10Zn clusters are spherically aromatic with 8 valence π-electrons. The enhanced stability of Sn12Zn (Ih) can further be rationalized in terms of its closed crystal field splitting shell. Highlights: → Small zinc doped tin clusters are studied using the DFT and CCSD(T) methods. → Icosahedral Sn12Zn (Ih) and Sn10Zn (D4d) are magic clusters. → Both Sn12Zn and Sn10Zn clusters are spherically aromatic species that satisfies the electron accounting rule of 2(N + 1)2. → Enhanced stability of Sn12Zn (Ih) can further be rationalized in terms of its closed crystal field splitting shell. - Abstract: Small zinc-doped tin clusters SnnZn, n = 1-12, are studied using DFT and CCSD(T) methods. The isomers are located using a stochastic search algorithm. The growth mechanism can be formulated as follows: (i) small clusters SnnZn with n ≤ 8 are formed by capping Zn on a surface of Snn, (ii) a competition between exohedral and endohedral structures appears at n = 9 and 10, from which the endohedral structures become predominant, (iii) for n = 11 and 12, the clusters are formed by encapsulating Zn into the empty cages Snn. Icosahedral Sn12Zn (Ih) and Sn10Zn (D4d) are magic clusters with large HOMO-LUMO gaps, high binding energies and embedding energies. While both Sn12Zn and Sn10Zn clusters can be considered to be spherically aromatic with 8 valence π-electrons that satisfy the electron count rule of 2(N + 1)2, the enhanced stability of Sn12Zn (Ih) can further be rationalized in terms of its closed crystal field splitting shell.