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RbSb 2 – Eine mit KSb 2 verwandte Zintl‐Phase
Author(s) -
Petri Denis,
Röhr Caroline
Publication year - 2008
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/zaac.200800136
Subject(s) - zintl phase , antimonide , crystallography , antimony , monoclinic crystal system , chemistry , crystal structure , single crystal , inorganic chemistry , organic chemistry
RbSb 2 – A Zintl Phase related to KSb 2 The electron‐precise Zintl compound RbSb 2 , which was known to melt incongruently at 418 °C, has been prepared in pure phase from elemental rubidium and antimony in sealed tantalum crucibles. In accordance with the ribbon‐shaped antimonide anions, the compound crystallizes with extremely thin intergrown, mechanically and chemically very sensitive needles of dark‐metallic lustre. The crystal structure could be determined and refined using single crystal x‐ray data (monoclinic, space group C2/m , a = 1403(2), b = 414.0(4), c = 855.7(14) pm, β = 104.45(12)°, Z = 4, R 1 = 0.0901) despite the poor quality of the crystals. It shows fused six‐membered rings of two‐ and three‐bonded Sb atoms forming ribbons running along the monoclinic b axis, which can be interpreted as sections of the elemental structure of antimony (d Sb‐Sb = 281.9(5) and 286.0(9) pm respectively). The structure of RbSb 2 is thus closely related to that of KSb 2 , which exhibits identical antimony anions. Compared to the potassium compound, the $^{1}_{\infty}\rm [Sb_{2}]^{-}$ ribbons are reoriented against each so that the coordination number of the A counter ions is increased from 6 + 2 (for A = K) to 8 + 2 (for A = Rb). The results of a FP‐LAPW band structure calculation of RbSb 2 are used to explain the chemical bonding in this classical Zintl phase with a calculated indirect band gap of 0.38 eV.