Fässler Thomas F, Hoffmann Stefan
Eduard-Zintl Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Petersenstrasse 18, D-64287 Darmstadt, Germany.
Inorg Chem. 2003 Sep 8;42(18):5474-6. doi: 10.1021/ic030148u.
Na(7)Sn(12) was synthesized by quenching of stoichiometric amounts of the elements (700 degrees C) in a sealed niobium ampule and further thermal treatment at 270 degrees C for 40 days. Single crystals of Na(7)Sn(12) were obtained from a mixture with the composition Na(6)SrSn(16). The structure of Na(7)Sn(12) consists of two-dimensional polyanions 2 (infinity) [Sn(12)(7-)], which are separated by Na atoms. Bonding Sn-Sn contacts in the polyanion vary between 2.827(2) and 3.088(2) A. Crystal data: monoclinic, P2/n, Z = 4, a = 13.375(3) A, b = 9.239(2) A, c = 17.976(4) A, gamma = 90.15(3) degrees, V = 2243.0(8) A(3), mu = 13.22 mm(-1), d(calc) = 4.694 g cm(-3), R1(F) = 6.1% (for all reflections). Extended-Hückel tight-binding calculations with the implementation the electron localization function (ELF) reveal that Na(7)Sn(12) can be viewed as an intermetallic compound with exclusively localized bonding and nonbonding regions as expected from the 8 - N rule. Thus Na(7)Sn(12) is a Zintl phase with the formula (Na(+))(7)(2b)Sn(2)(-)(3b)Sn(-)(4b)Sn(0).
通过在密封的铌安瓿中对化学计量比的元素进行淬火（700℃），然后在270℃下进一步热处理40天，合成了Na(7)Sn(12)。Na(7)Sn(12)的单晶是从组成为Na(6)SrSn(16)的混合物中获得的。Na(7)Sn(12)的结构由二维聚阴离子2 (∞)[Sn(12)(7-)]组成，这些聚阴离子被Na原子隔开。聚阴离子中Sn-Sn键的接触距离在2.827(2)至3.088(2) Å之间变化。晶体数据：单斜晶系，P2/n，Z = 4，a = 13.375(3) Å，b = 9.239(2) Å，c = 17.976(4) Å，γ = 90.15(3)°，V = 2243.0(8) Å(3)，μ = 13.22 mm(-1)，d(calc) = 4.694 g cm(-3)，R1(F) = 6.1%（对于所有反射）。采用电子定域函数（ELF）的扩展休克尔紧束缚计算表明，Na(7)Sn(12)可被视为一种金属间化合物，具有如8 - N规则所预期的完全定域的键合和非键合区域。因此，Na(7)Sn(12)是一种具有化学式(Na(+))(7)(2b)Sn(2)(-)(3b)Sn(-)(4b)Sn(0)的津特耳相。
