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Peierls‐Distorted Monoclinic MnB 4 with a MnMn Bond
Author(s) -
Knappschneider Arno,
Litterscheid Christian,
George Nathan C.,
Brgoch Jakoah,
Wagner Norbert,
Beck Johannes,
Kurzman Joshua A.,
Seshadri Ram,
Albert Barbara
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201306548
Subject(s) - monoclinic crystal system , crystallography , tetragonal crystal system , boron , fermi level , paramagnetism , atom (system on chip) , materials science , bond length , manganese , density functional theory , diamond , crystal structure , chemistry , condensed matter physics , physics , computational chemistry , electron , organic chemistry , quantum mechanics , computer science , embedded system , composite material , metallurgy
Tetraborides of chromium and manganese exhibit an unusual boron‐atom framework that resembles the hypothetical tetragonal diamond. They are believed to be very hard. Single crystals of MnB 4 have now been grown. The compound crystallizes in the monoclinic crystal system (space group P 2 1 / c ) with a structure that has four crystallographically independent boron‐atom positions, as confirmed by 11 B MAS‐NMR spectroscopy. An unexpected short distance between the Mn atoms suggests a double Mn–Mn bond and is caused by Peierls distortion. The structure was solved using group‐subgroup‐relationships. DFT calculations indicate Mn I centers and paramagnetism, as confirmed by magnetic measurements. The density of states shows a pseudo‐band gap at the Fermi energy and semiconducting behavior was observed for MnB 4 .