R. Dronskowski, INFEBR3 AND INMNBR3 - SYNTHESIS, CRYSTAL-STRUCTURE, MAGNETIC-PROPERTIES, AND ELECTRONIC STRUCTURE, Inorganic chemistry, 33(25), 1994, pp. 5927-5933
Yellow and pink crystals of InFeBr3 and InMnBr3, the first structurall
y characterized transition metal bromides containing univalent indium,
are synthesized from elemental Fe/Mn and molten InBr3. The orthorhomb
ic crystal structures (InFeBr3: a = 934.81(9) pm, b = 394.35(4) pm, c
= 1514.1(2) pm; InMnBr3: a = 943.1(1) pm, b = 398.95(4) pm, c = 1535.3
(2) pm; Pnma, Z = 4) are isotypic with NH4CdCl3. While the transition
metals cations are octahedrally coordinated by Br- anions, monovalent
indium cations are found in strongly distorted trigonal Br- prisms whi
ch are tricapped by additional Br- anions. InFeBr3 and InMnBr3 show Cu
rie-Weiss paramagnetism whereas only InFeBr3 exhibits antiferromagneti
c ordering below 15 K. Semiempirical band structure calculations (CSC-
EH-TB) reflect strongly covalent contributions to In+-Br- bonding, exc
eeding those interactions found in the binary In/Br crystal chemical s
ystem. Moreover, there is weak In+-In+ bonding between neighboring uni
t cells. Valence charge density plots based on ab initio band structur
e computations (TB-LMTO-ASA) disprove the existence of a directional e
lectron ''lone-pair'' centered on monovalent In.