Stabilization of titanium(IV) and indium(III) complexes by coordination of [MoO3(1,4,7-triazacyclononane)] metalloligand in aqueous solution
Stabilization of titanium(IV) and indium(III) complexes by coordination of [MoO3(1,4,7-triazacyclononane)] metalloligand in aqueous solution
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DOI：
10.1016/j.ica.2020.119691
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发表时间：
2020-09
影响因子：
2.8
通讯作者：
Sugiarto;Shota Kazakami;K. Kawamoto;Y. Hayashi
中科院分区：
文献类型：
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作者：
Sugiarto;Shota Kazakami;K. Kawamoto;Y. Hayashi
一种中性的弱给体[MoO3(tacn)] （tacn = 1,4,7-三氮杂环壬烷）金属配体被证明可以稳定水溶液中的Ti4+或In3+阳离子。因此，[MoO3(tacn)]与tioso4或In(NO3)3在水中的反应分别产生络合阳离子[Ti{MoO3(tacn)}6]4+(1)或[In{MoO3(tacn)}6]3+(2)。Ti4+或In3+阳离子由六个[MoO3(tacn)]金属配位体进行异构配位。每个[MoO3(tacn)]通过其三个氧原子中的一个来配位Ti4+或In3+；另外两个氧与相邻的[MoO3(tacn)]的NH基团成氢键。这些氢键网络(i)加强了[MoO3(tacn)]与Ti4+或In3+中心的配位，（ii）将六个[MoO3(tacn)]单元定向成两个可以捕获阳离子的三脚架状臂。其中一个臂通过非共价CH··O键在1中结合四甲基铵阳离子，或通过In - O配位键在2中结合ac-{In(OH2)3}3+阳离子。配合物1可在干燥的乙腈中完整溶解，经1h NMR和esi -质谱分析证实。在乙腈溶液中加入水或甲酰胺会破坏氢键网络，触发[MoO3(tacn)]与Ti4+的解离，重要的是，解离配体的数量可以通过改变水或甲酰胺的量来控制。因此，1是自下而上合成钛-氧簇的重要前驱体。
A neutral weakly-donating [MoO3(tacn)] (tacn = 1,4,7-triazacyclononane) metalloligand has proved useful to stabilize Ti4+or In3+cation in aqueous solution. Thus, the reaction of [MoO3(tacn)] with TiOSO4or In(NO3)3in water affords a complex cation [Ti{MoO3(tacn)}6]4+(1) or [In{MoO3(tacn)}6]3+(2), respectively. The Ti4+or In3+cation is homoleptically coordinated by six [MoO3(tacn)] metalloligands. Each [MoO3(tacn)] coordinates Ti4+or In3+via one of its three oxygen atoms; the other two oxygens are hydrogen-bonded to NH groups of the neighboring [MoO3(tacn)]. These hydrogen bonding networks (i) strengthen [MoO3(tacn)] coordination to the Ti4+or In3+center and (ii) orient the six [MoO3(tacn)] units into two tripod-like arms that can catch a cation. One of the arms binds a tetramethylammonium cation through non-covalent CH···O bonds in1or afac-{In(OH2)3}3+cation through In–O coordination bonds in2. Complex1dissolves intact in dry acetonitrile, as confirmed by1H NMR spectroscopy and ESI-mass spectrometry. Addition of water or formamide to the acetonitrile solution disrupts the hydrogen bond networks and triggers dissociation of [MoO3(tacn)] from Ti4+, and importantly, the number of dissociated ligands can be managed by changing the amount of water or formamide. Therefore1is a prominent precursor for bottom-up synthesis of titanium–oxo clusters.