Premium
Orthonitridoborate Ions [BN 3 ] 6− in Oxonitridosilicate Cages: Synthesis, Crystal Structure, and Magnetic Properties of Ba 4 Pr 7 [Si 12 N 23 O][BN 3 ], Ba 4 Nd 7 [Si 12 N 23 O][BN 3 ], and Ba 4 Sm 7 [Si 12 N 23 O][BN 3 ]
Author(s) -
Orth Michael,
Hoffmann RolfDieter,
Pöttgen Rainer,
Schnick Wolfgang
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010702)7:13<2791::aid-chem2791>3.0.co;2-q
Subject(s) - crystallography , crystal structure , ion , stoichiometry , chemistry , tungsten , boron , barium , materials science , inorganic chemistry , metallurgy , organic chemistry
The isotypic title compounds Ba 4 Pr 7 [Si 12 N 23 O][BN 3 ], Ba 4 Nd 7 [Si 12 N 23 O][BN 3 ], and Ba 4 Sm 7 [Si 12 N 23 O][BN 3 ] were prepared by reaction of Pr, Nd, or Sm, with barium, BaCO 3 , Si(NH) 2 , and poly(boron amide imide) in nitrogen atmosphere in tungsten crucibles using a radiofrequency furnace at temperatures up to 1650 °C. They were obtained as main products (≈70 %) embedded in a very hard glass matrix in the form of intense dark green (Pr), orange‐brown (Sm), or dark red (Nd) large single crystals, respectively. The stoichiometric composition of Ba 4 Sm 7 [Si 12 N 23 O][BN 3 ] was verified by a quantitative elemental analysis. According to the single‐crystal X‐ray structure determinations (Ba 4 Ln 7 [Si 12 N 23 O][BN 3 ], Z =1, P $\bar 6$ with Ln=Pr: a =1225.7(1), c =544.83(9) pm, R 1=0.013, wR 2=0.030; Ln=Nd: a =1222.6(1), c =544.6(1) pm, R 1=0.017, wR 2=0.039; Ln=Sm: a =1215.97(5), c =542.80(5) pm, R 1=0.047, wR 2=0.099) all three compounds are built up by a framework structure [Si 12 N 23 O] 23− of corner‐sharing SiX 4 tetrahedrons (X=O, N). The oxygen atoms are randomly distributed over the X positions. The trigonal‐planar orthonitridoborate ions [BN 3 ] 6− and also the Ln(3) 3+ are situated in hexagonal cages of the framework (bond lengths Si−(N/O) 169–179 pm for Ln=Pr). The remaining Ba 2+ and Ln 3+ ions are positioned in channels of the large‐pored network. The trigonal‐planar [BN 3 ] 6− ions have a B−N distance of 147.1(6) pm (for Ln=Pr). Temperature‐dependent susceptibility measurements for Ba 4 Nd 7 [Si 12 N 23 O][BN 3 ] revealed Curie–Weiss behavior above 60 K with an experimental magnetic moment of μ exp =3.36(5) μ B /Nd. The deviation from Curie–Weiss behavior below 60 K may be attributed to crystal field splitting of the J =9/2 ground state of the Nd 3+ ions. No magnetic ordering is evident down to 4.2 K.