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Nb 2 Se 2 I 6 : Eine neue Strukturvariante bei Niobchalkogenidhalogeniden mit Kettenstruktur
Author(s) -
Schmidt Peter J.,
Thiele Gerhard
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(199907)625:7<1056::aid-zaac1056>3.0.co;2-h
Subject(s) - triclinic crystal system , monoclinic crystal system , crystallography , niobium , crystal structure , materials science , chemistry , metallurgy
Nb 2 Se 2 I 6 : A New Structural Variation of Niobium Chalcogenide Halides with Chain Structure Single crystals of Nb 2 Se 2 I 6 , exhibiting a metallic lustre, (monoclinic, C 2/ c ; a = 7.110(1), b = 13.899(3), c = 13.688(3) Å, β = 99.58(3)°; Z = 8) have been obtained by heating mixture of the elements (molar ratio Nb : Se : I = 3 : 1 : 7) in evacuated sealed fused silica tubes at 1073 K for two weeks. After rapid quenching, the tube was reheated to 773 K and then cooled at a rate of 2 K h –1 . Crystals of the title compound formed at the colder part of the tube besides higher niobium iodides. Nb 2 Se 2 I 6 can also be obtained by slow cooling of a stoichiometric mixture of the elements from 1073 K as a minor product besides triclinic NbSe 2 I 2 [1]. The crystal structure is built up with one‐dimensional infinite chains 1 ∞ [Nb 2 Se 2 I 4 I 4/2 ]. The main structural features are a short Nb–Nb distance (2.903(1) Å) and a short Se–Se distance (2.318(2) Å) which is expected for +4 and –1 oxidation states, respectively. Homeotypic phases with Nb 2 Y 2 X 6 chains (Y = Se, Te; X = Br, I) are known [2] except for the combination Y = Se, X = I. They show a primitive rod packing of the Nb 2 Y 2 X 6 chains in contrast to the title compound which shows a centered rod packing.