The route to highly stable MeBxNyCz molecular wheels. I. The features of preliminary results

By means of ab initio quantum chemical methods we have determined the energies and electronic structures of molecular wheels TiBn, TiBnN10−n, TiCnN10−n and TiCnB10−n (for n = 0–10). The ground state energies and the corresponding spin states of each atom, cluster and molecular wheel were calculated first in the framework of Hartree-Fock self-consistent-field (HF-SCF) using minimal and more accurate basis sets STO-3G and 6-31G. Computations at higher level and accuracy are processing in a follow-up study. The most stable wheel system is TiCnB10−n (for n = 5–10). Thereof particularly highly stable is the TiC5B5 molecular wheel followed by the TiC6B4. At the HF-SCF/6-31G level, however, we have calculated the wheel system MeC5B5 considering for Me, the first row of transition metal atoms Me = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. The molecular wheel MeC5B5 favours Sc atom at the centre, but also Ti and Fe are the next favoured atoms.

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► Building molecular wheels starting by an arc up to cyclic boron rings around central transition metal atoms.
► Developing a novel route towards high stability by doping boron with nitrogen or carbon atoms.
► High spin states are favored for the most ground states of the molecular wheels.
►  The molecular wheel MeB5C5 favors Ti at the center but also Sc and Fe as next.
► The molecular wheels are high aromatic.