Go Yong Bok, Wang Xiqu, Anokhina Ekaterina V, Jacobson Allan J
Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA.
Inorg Chem. 2005 Nov 14;44(23):8265-71. doi: 10.1021/ic050644d.
Three new Ni(BDC)/2,2'-bipy compounds, Ni2(BDC)(HBDC)2(2,2'-bipy)2 (2), Ni3(BDC)3(2,2'-bipy)2 (3), and Ni(BDC)(2,2-bipy)2.2H2O (5), in addition to the previously reported Ni(BDC)(2,2'-bipy).0.75H2BDC (1) and Ni(BDC)(2,2'-bipy)(H2O) (4) [BDC = 1,4-benzenedicarboxylate; 2,2'-bipy = 2,2'-bipyridine], have been synthesized by hydrothermal reactions. A systematic investigation of the effect of the reaction temperature and pH resulted in a series of compounds with different compositions and dimensionality. The diverse product slate illustrates the marked sensitivity of the structural chemistry of polycarboxylate aromatic ligands to synthesis conditions. Compound 1, which has a channel structure containing guest H2BDC molecules, is formed at the lowest pH. The guest H2BDC molecules are connected by hydrogen bonds and form extended chains. At a slightly higher pH, a dimeric molecular compound 2 is formed with a lower number of protonated carboxylate groups per nickel atom and per BDC ligand. Reactions at higher temperature and the same pH lead to the transformation of 1 and 2 into the two-dimensional, layered trinuclear compound 3. As the pH is increased, a one-dimensional polymer 4 is formed with a water molecule coordinated to Ni2+. Bis-monodentate and bischelating BDC ligands alternate along the chain to give a crankshaft rather than a regular zigzag arrangement. A further increase of the pH leads to the one-dimensional chain compound 5, which has two chelating 2,2'-bipy ligands. Crystal data: 2, triclinic, space group P, a = 7.4896(9) angstroms, b = 9.912(1) angstroms, c = 13.508(2) angstroms, alpha = 86.390(2) degrees , beta = 75.825(2) degrees, gamma = 79.612(2) degrees, Z = 2; 3, orthorhombic, space group Pbca, a = 9.626(2) angstroms, b = 17.980(3) angstroms, c = 25.131(5) angstroms, Z = 4; 5, orthorhombic, space group Pbcn, a = 14.266(2) angstroms, b = 10.692(2) angstroms, c = 17.171(2) angstroms, Z = 8.
除了之前报道的Ni(BDC)(2,2'-bipy)·0.75H₂BDC (1)和Ni(BDC)(2,2'-bipy)(H₂O) (4) [BDC = 1,4-苯二甲酸根；2,2'-bipy = 2,2'-联吡啶]之外，通过水热反应合成了三种新的Ni(BDC)/2,2'-bipy化合物，即Ni₂(BDC)(HBDC)₂(2,2'-bipy)₂ (2)、Ni₃(BDC)₃(2,2'-bipy)₂ (3)和Ni(BDC)(2,2-bipy)₂·2H₂O (5)。对反应温度和pH值影响的系统研究产生了一系列具有不同组成和维度的化合物。多样的产物情况说明了多羧酸芳香配体的结构化学对合成条件具有显著的敏感性。化合物1具有包含客体H₂BDC分子的通道结构，在最低pH值下形成。客体H₂BDC分子通过氢键连接并形成延伸链。在稍高的pH值下，形成了一种二聚体分子化合物2，每个镍原子和每个BDC配体的质子化羧酸根基团数量较少。在较高温度和相同pH值下的反应导致1和2转变为二维层状三核化合物3。随着pH值的增加，形成了一种一维聚合物4，其中一个水分子与Ni²⁺配位。双单齿和双螯合的BDC配体沿着链交替排列，形成曲轴状而非规则的锯齿状排列。pH值的进一步增加导致了具有两个螯合2,2'-bipy配体 的一维链状化合物5。晶体数据：2，三斜晶系，空间群P，a = 7.4896(9)埃，b = 9.912(1)埃，c = 13.508(2)埃，α = 86.390(2)°，β = 75.825(2)°，γ = 79.612(2)°，Z = 2；3，正交晶系，空间群Pbca，a = 9.626(2)埃，b = 17.980(3)埃，c = 25.131(5)埃，Z = 4；5，正交晶系，空间群Pbcn，a = 14.266(2)埃，b = 10.692(2)埃，c = 17.171(2)埃，Z = 8。
