Chapman Karena W, Chupas Peter J, Kepert Cameron J
School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
J Am Chem Soc. 2006 May 31;128(21):7009-14. doi: 10.1021/ja060916r.
The effect of M(II) substitution on the magnitude of the negative thermal expansion (NTE) behavior within a series of Prussian Blue analogues, M(II)Pt(IV)(CN)(6) for M(II) = Mn, Fe, Co, Ni, Cu, Zn, Cd, has been investigated using variable-temperature powder X-ray diffraction (100-400 K). The NTE behavior varies widely with M(II) substitution, from near zero thermal expansion in NiPt(CN)(6) (alpha = dl/l dT = -1.02(11) x 10(-)(6) K(-)(1)) up to a maximum in CdPt(CN)(6) (alpha = -10.02(11) x 10(-)(6) K(-)(1)). The trend in the magnitude of the NTE behavior, with increasing atomic number (Z) of the M(II) ion, follows the order Mn(II) > Fe(II) > Co(II) > Ni(II) < Cu(II) < Zn(II) < Cd(II), which correlates with the trends for M(II) cation size, the lattice parameter, and structural flexibility as indicated by the temperature-dependent structural refinements and Raman spectroscopy. Analysis of the temperature dependence of the average structures suggests that the differences in the thermal expansion are due principally to the different strengths of the metal-cyanide binding interaction and, accordingly, the different energies of transverse vibration of the cyanide bridge, with enhanced NTE behavior for more flexible lattices.
利用变温粉末X射线衍射（100 - 400K）研究了M（II）取代对一系列普鲁士蓝类似物M（II）Pt（IV）（CN）₆（M（II） = Mn、Fe、Co、Ni、Cu、Zn、Cd）中负热膨胀（NTE）行为大小的影响。NTE行为随M（II）取代而有很大变化，从NiPt（CN）₆中接近零的热膨胀（α = dl/l dT = -1.02(11)×10⁻⁶ K⁻¹）到CdPt（CN）₆中的最大值（α = -10.02(11)×10⁻⁶ K⁻¹）。随着M（II）离子原子序数（Z）增加，NTE行为大小的趋势遵循Mn（II）> Fe（II）> Co（II）> Ni（II）< Cu（II）< Zn（II）< Cd（II）的顺序，这与M（II）阳离子尺寸、晶格参数以及温度相关结构精修和拉曼光谱所表明的结构灵活性趋势相关。对平均结构温度依赖性的分析表明，热膨胀差异主要归因于金属 - 氰化物键合相互作用的不同强度，以及相应地氰化物桥横向振动的不同能量，晶格越灵活，NTE行为越强。
