Seminarium "Modeling of Complex Systems"

Successful incorporation of metal (M) atoms into the core of planar boron clusters Bn yields a fascinating class of borometallic molecules [1]. These novel compounds exhibit variable ring sizes, namely MBn and MB−n with n = 8–10 and have been characterized through size-selected anion photoelectron spectroscopy [2]. In these molecular wheels, each B atom in the circumference contributes two electrons to the B–B peripheral covalent bonds and one electron to the delocalized bonds. So, an atom with the appropriate number of valence electrons can fit into the center of the boron wheel to make the MBn clusters. Delocalized bonding between the metalatom and the boron ring and localized bonding at the periphery of MBn made metal atomspromising candidates for the central position of the ring clusters to make an electronically stable borometallic cluster compound. Here, we show the results of first-principles calculations to study the electronic and magnetic properties of boron rings with a transition metal (TM) in thecenter, TMB8−10 (TM = Ti, Cr, Mn, Fe, Co, Nb, or Mo), and boron double-rings sandwiching the metal atom, TM–2B8−10. Our study reveals that the overall magnetic moment of the clusters is a combination of the magnetic moment of the central metal ion and the induced magnetic moment of the peripheral boron atoms. These molecular-based magnets offer a platform tostudy magnetism in the zero-dimensional limit. Moreover, the TM–2B8−10 clusters can serve as building blocks of one-dimensional tubular forms.[1] C. Romanescu et al., Angewandte Chemie International Edition 50, 9334 (2011).[2] C. Romanescuet al., Accounts of Chemical Research 46, 350 (2012).