Gold Complexes with Tridentate Cyclometalating and NHC Ligands: A Search for New Photoluminescent Gold(III) Compounds
Gold Complexes with Tridentate Cyclometalating and NHC Ligands: A Search for New Photoluminescent Gold(III) Compounds
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DOI：
10.1021/om301226b
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发表时间：
2013-03-25
期刊：
影响因子：
2.8
通讯作者：
Wenger, Oliver S.
中科院分区：
文献类型：
--
作者：
Herbst, Annika;Bronner, Catherine;Wenger, Oliver S.
许多正方形平面的Pt（II）配合物是强烈的光致发光的，特别是当它们含有产生强配体场的环化和/或NHC配体时。在这项工作中，我们研究了获得具有良好发光性能的等电子Au（III）配合物的可能性。为此，探索了金与三种不同（潜在的）三齿配体的配位化学：1，3-双（1-己基-2 '-苯并咪唑基）苯（（LH）-H-1）、2，6-双（3-丁基咪唑-1-鎓）吡啶（L2 H22+）和2，6-双（3-己基苯并咪唑-1-鎓）吡啶（（LH 22+）-H-3）。Pt（II）或Pd（II）络合物对于所有这些配体或密切相关的类似物是已知的，因此我们预期类似的Au（III）络合物也将是可合成的。这被证明是唯一的L-1的情况下，尽管探索不同的合成路线，包括（i）直接络合的Au（III），（ii）transmetalation从Ag（I）前体络合物，和（iii）transmetalation从合适的Hg（II）前体。只有汞的过程是成功的（至少在L-1的情况下）;在大多数情况下，从银的金属转移或直接络合产生其他含有Au（I）的反应产物。同样，用配体L-2和L-3主要得到Au（I）的配合物：即，金倾向于低氧化态是获得所需Au（III）化合物的主要障碍。对几种新的Au（I）和Au（III）配合物进行了晶体学表征。我们的研究结果提供了深入了解之间的差异的配位化学的等电子Pt（II）和Au（III）与三齿环化和NHC配体。
Many square-planar Pt(II) complexes are strongly photoluminescent, particularly when they contain cyclometalating and/or NHC ligands which produce strong ligand fields. In this work we investigated the possibility of obtaining isoelectronic Au(III) complexes with favorable luminescence properties. Toward this end, the coordination chemistry of gold with three different (potentially) tridentate ligands was explored: 1,3-bis(1-hexyl-2'-benzimidazoyl)benzene ((LH)-H-1), 2,6-bis(3-butylimidazol-1-ium)pyridine (L2H22+) and 2,6-bis(3-hexylbenzimidazol-1-ium)pyridine ((LH22+)-H-3). Pt(II) or Pd(II) complexes are known for all of these ligands or closely related analogues, and hence we anticipated that similar Au(III) complexes would be synthetically accessible as well. This turned out to be the case only for L-1, despite exploration of different synthetic routes including (i) direct complexation of Au(III), (ii) transmetalation from Ag(I) precursor complexes, and (iii) transmetalation from suitable Hg(II) precursors. Only the mercury procedure was successful (at least in the case of L-1); transmetalation from silver or direct complexation yields other reaction products containing Au(I) in most cases. Likewise, with ligands L-2 and L-3 mainly complexes of Au(I) were obtained: i.e., the propensity of gold for low oxidation states is a major obstacle to obtaining the desired Au(III) compounds. Several new complexes of Au(I) and Au(III) were characterized crystallographically. Our results provide insight into the differences between the coordination chemistry of isoelectronic Pt(II) and Au(III) with tridentate cyclometalating and NHC ligands.