Structures and properties of 6-aryl substituted tris(2-pyridylmethyl)-amine transition metal complexes
Structures and properties of 6-aryl substituted tris(2-pyridylmethyl)-amine transition metal complexes
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DOI：
10.1039/b207406k
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发表时间：
2002-01-01
期刊：
影响因子：
--
通讯作者：
Colbran, SB
中科院分区：
文献类型：
--
作者：
He, ZC;Craig, DC;Colbran, SB
合成了一系列[6-(2‘，5’-二甲氧基苯基)-2-吡啶甲基]双(2-吡啶甲基)胺(L)的金属(II)配合物。测定了L及其与锰、铁、钴、镍、铜、锌的金属(II)氯化物的X射线晶体结构，并对结果进行了比较。报道了一种特殊的碳桥联铜四聚体[Cu-4(L)(4)(CO3)(2)][BF4](4).5.2H(2)O的合成和晶体结构。根据它们的物理化学性质和光谱性质推测了它们的溶液状态结构。锌(II)配合物[ZnCl2(L)]在核磁共振时间刻度上显示了配位基的反转--变温核磁共振研究的结果表明，胺反转的势垒为56+/-0.5kJ摩尔(-1)。总之，研究发现，由于三(2-吡啶甲基)胺(TPA)骨架被一个6-芳基取代而引入的分子内空间相互作用导致了金属配合物的结构和性质的显著变化：特别是L中的芳基取代导致(I)与TPA相比更弱的配位场有利于高自旋配合物，(Ii)倾向于低配位数，以及(Iii)在Ni(II)和Cu(II)配合物中的半配位性-配体(L)的芳基取代支链是配位不稳定的。
A series of metal(II) complexes of [6-(2',5'-dimethoxyphenyl)-2-pyridylmethyl] bis(2-pyridylmethyl) amine (L) have been prepared. X-Ray crystal structures have been determined for L and its metal(II) chloride complexes for Mn, Fe, Co, Ni, Cu and Zn and the results compared. The preparation and crystal structure of the unusual carbonato-bridged copper-tetramer [Cu-4(L)(4)(CO3)(2)][BF4](4).5.2H(2)O is also described. The solution-state structures of the complexes are deduced from their physicochemical and spectroscopic properties. The Zn(II) complex, [ZnCl2(L)], shows inversion about the ligand amine group on the NMR timescale - results from a variable temperature NMR study are presented and allow estimation of the barrier to amine inversion as 56 +/- 0.5 kJ mol(-1). Overall, it is found that the intramolecular steric interactions introduced by substitution of the tris(2-pyridylmethyl) amine (tpa)- skeleton by a single 6-aryl group result in significant changes to the structures and properties of the resulting metal complexes: in particular the aryl-substitution in L causes (i) a weaker ligand-field compared to tpa favouring high-spin complexes, (ii) a tendency toward lower coordination numbers, and (iii) hemilability in the Ni(II) and Cu(II) complexes - the aryl-substituted leg of the ligand (L) is coordinatively labile.