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首页> 外文期刊>Chemistry: A European journal >The heteropolytungstate core {BW13O46}(11-) derived as monomer, dimer, and trimer
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The heteropolytungstate core {BW13O46}(11-) derived as monomer, dimer, and trimer

机译：衍生为单体，二聚体和三聚体的杂多钨酸盐核{BW13O46}（11-）

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A study of the borotungstate system has led to the characterization of new, original compounds based on the unconventional Keggin derivative [H3BW13O46](8-) ion (denoted as 1). [H3BW14O48](6-) (2) and the dimer [H6B2W26O90](12-) (3) crystallize as mixed cesium/ammonium salts and have been characterized by single-crystal X-ray diffraction analysis. Anion 2 reveals an unusual arrangement, consisting of an outer {W3O9} core grafted onto the monovacant [BW11O39](9-) Keggin moiety and exhibits an unprecedented distorted square-pyramidal arrangement for a cis-{WO2} core. Elemental analysis, supported by bond distance analysis, is consistent with the presence of three protons distributed over the terminal oxygens of the outer {W3O7} capping fragment. The [H6B2W26O90](12-) ion (3) is formally derived from the direct condensation of two [H3BW13O46](8-) subunits. The cisoid arrangement of the two [BW11O39](9-) subunits, coupled with the antiparallel arrangement of the two quasi-linear O=W center dot center dot center dot O=W-OH2 chains within the central {W4O12} connecting group, breaks any symmetry, thereby resulting in a chiral compound. Polarography and pH-metric titrations reveal the formation of the monomeric precursor [H3BW13O46](8-) (anion 1) under stoichiometric conditions. W-183 NMR analysis of 2 and 3 in solution gives complex spectra, consistent with the presence of equilibria between several species. In the frame of this study, we also report on a structural re-investigation of the [H6B3W39O132](15-) ion (4) based on reliable results obtained in the solid state by means of single-crystal X-ray diffraction analysis, and in solution by means of ID and 2D COSY W-183 NMR. X-ray diffraction analysis revealed the presence of three attached aquo ligands on the central {W6O15} connecting core, generating three O= W center dot center dot center dot O=W-OH2 quasi-linear chains, which are responsible for the chirality of the trimeric assembly. This structural arrangement accounts for the 39-line W-183 solution spectrum. The 2D COSY spectrum permits reliable assignments of the six strongly shielded resonances (around -250 and -400ppm) to the six central W atoms, as well as additional assignments. The origin of such strong shielding for these particular W atoms is discussed on the basis of previously published results. Infrared data for compounds 1, 3, and 4 are also presented.
机译：对硼钨酸盐体系的研究导致了基于非常规Keggin衍生物[​​H3BW13O46]（8-）离子（表示为1）的新的原始化合物的表征。 [H3BW14O48]（6-）（2）和二聚体[H6B2W26O90]（12-）（3）结晶为铯/铵盐混合盐，并已通过单晶X射线衍射分析进行了表征。阴离子2揭示了一个不寻常的排列，由嫁接到单空[BW11O39]（9-）Keggin部分上的{W3O9}外部核组成，并显示了顺式{WO2}核前所未有的扭曲的方金字塔形排列。结合距离分析支持的元素分析与分布在外部{W3O7}封端片段末端氧上的三个质子的存在是一致的。 [H6B2W26O90]（12-）离子（3）正式源自两个[H3BW13O46]（8-）亚基的直接缩合。两个[BW11O39]（9-）子单元的胞状排列，再加上中心{W4O12}连接组中的两个准线性O = W中心点中心点中心点O = W-OH2链的反平行排列，破坏任何对称性，从而产生手性化合物。极谱法和pH滴定法揭示了在化学计量条件下单体前体[H3BW13O46]（8-）（阴离子1）的形成。溶液中2和3的W-183 NMR分析得出复杂的光谱，与几种物质之间存在平衡相一致。在这项研究的框架中，我们还报告了[H6B3W39O132]（15-）离子（4）的结构再研究，该结果基于通过单晶X射线衍射分析获得的固态可靠结果，并且通过1D和2D COZY W-183 NMR在溶液中。 X射线衍射分析表明，在中心{W6O15}连接核上存在三个附着的aquo配体，产生了三个O = W中心点中心点中心点中心点O = W-OH2准线性链，这些链负责手性三聚体组装体。这种结构安排说明了39行W-183解决方案的范围。 2D COZY光谱允许将六个强屏蔽共振（大约-250和-400ppm）可靠地分配给六个中心W原子，以及进行其他分配。在以前发表的结果的基础上讨论了对这些特定的W原子如此强屏蔽的起源。还提供了化合物1、3和4的红外数据。

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