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The Nitrido Borates Ln 3 B 2 N 4 (Ln = La–Nd) and La 5 B 4 N 9 : Syntheses, Structures, and Properties
Author(s) -
Reckeweg Olaf,
Meyer H.Jürgen
Publication year - 1999
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199906)625:6<866::aid-zaac866>3.0.co;2-3
Subject(s) - chemistry , crystallography , boron , lanthanide , oxalate , valence (chemistry) , crystal structure , metal , ion , inorganic chemistry , stereochemistry , organic chemistry
Single crystals of the lanthanoide nitrido borates Ln 3 B 2 N 4 (Ln = La–Nd) and La 5 B 4 N 9 have been obtained from reactions of lanthanoide metal powder, lanthanoide nitride powder, and hexagonal boron nitride in calcium chloride melts. The isotypic compounds Ln 3 B 2 N 4 belong to the space group Immm (#71), Z = 2, with the lattice parameters for La 3 B 2 N 4 : a = 362.94(3), b = 641.25(6), c = 1097.20(8) pm; Ce 3 B 2 N 4 : a = 356.20(3), b = 631.90(6), c = 1071.91(8) pm; Pr 3 B 2 N 4 : a = 353.46(4), b = 630.04(13), c = 1079.04(23) pm and Nd 3 B 2 N 4 : a = 351.52(4), b = 627.01(15), c = 1075.59(23) pm. The structure of La 5 B 4 N 9 has been determined in the space group Pbcm (#57), Z = 4, with a = 988.25(5); b = 1263.48(7), c = 770.33(4) pm. These two structure types resemble three kinds of nitrido borate anions, the oxalate analogue B 2 N 4 of Ln 3 B 2 N 4 , and the carbonate analogue BN 3 together with the six‐membered ring system B 3 N 6 of La 5 (BN 3 )(B 3 N 6 ). In contrast to the valence compound La 5 B 4 N 9 the compounds (Ln 3+ ) 3 (B 2 N 4 ) 8– (e – ) contain one electron in the conduction band, yielding temperature independent paramagnetism for La 3 B 2 N 4 . The calculated electronic structure is developed through the formation of B 2 N 4 8– ions by dimerisation of two BN 2 units.