亲金属性对一系列同构二氰基金属配位聚合物中“巨大”正负热膨胀的影响
Impact of metallophilicity on "colossal" positive and negative thermal expansion in a series of isostructural dicyanometallate coordination polymers.
作者信息
Korcok Jasmine L, Katz Michael J, Leznoff Daniel B
机构信息
Department of Chemistry, Simon Fraser University, 8888 University Dr., Burnaby, BC, Canada V5A 1S6.
出版信息
J Am Chem Soc. 2009 Apr 8;131(13):4866-71. doi: 10.1021/ja809631r.
Five isostructural dicyanometallate coordination polymers containing metallophilic interactions (InM(CN)(2) (M = Ag, Au), KCdM(CN)(2), and KNiAu(CN)(2)) were synthesized and investigated by variable-temperature powder X-ray diffraction to probe their thermal expansion properties. The compounds have a trigonal unit cell and show positive thermal expansion (PTE) in the ab plane, where Kagome sheets of M atoms reside, and negative thermal expansion (NTE) along the trigonal c axis, perpendicular to these sheets. The magnitude of thermal expansion is unusually large in all cases (40 x 10(-6) K(-1) < |alpha| < 110 x 10(-6) K(-1)). The system with the weakest metallophilic interactions, InAg(CN)(2), shows the most "colossal" thermal expansion of the series (alpha(a) = 105(2) x 10(-6) K(-1), alpha(c) = -84(2) x 10(-6) K(-1) at 295 K), while systems containing stronger Au-Au interactions show relatively reduced thermal expansion. Thus, it appears that strong metallophilic interactions hinder colossal thermal expansion behavior. Additionally, the presence of K(+) counterions also reduces the magnitude of thermal expansion.
合成了五种含有亲金属相互作用的同构双氰基金属配位聚合物（InM(CN)(2) （M = Ag、Au）、KCdM(CN)(2)和KNiAu(CN)(2)），并通过变温粉末X射线衍射对其进行研究，以探究它们的热膨胀性质。这些化合物具有三方晶胞，在M原子所在的ab平面显示正热膨胀（PTE），而在垂直于这些平面的三方c轴方向显示负热膨胀（NTE）。在所有情况下，热膨胀的幅度都异常大（40×10⁻⁶ K⁻¹ < |α| < 110×10⁻⁶ K⁻¹）。亲金属相互作用最弱的体系InAg(CN)(2)在该系列中表现出最“巨大”的热膨胀（在295 K时，α(a) = 105(2)×10⁻⁶ K⁻¹，α(c) = -84(2)×10⁻⁶ K⁻¹），而含有较强Au-Au相互作用的体系热膨胀相对减小。因此，似乎强亲金属相互作用会阻碍巨大的热膨胀行为。此外，K⁺抗衡离子的存在也会降低热膨胀的幅度。
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