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首页> 外文期刊>Chemistry: A European journal >Proton-transfer reactions on hexanuclear platinum clusters: Reversible heterolytic cleavage of H_2 and C-H activation affording a linear, cluster-containing polymer
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Proton-transfer reactions on hexanuclear platinum clusters: Reversible heterolytic cleavage of H_2 and C-H activation affording a linear, cluster-containing polymer

机译：六核铂簇上的质子转移反应：H_2和C-H活化的可逆杂溶裂解，得到线性的，含簇的聚合物

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摘要

The hexanuclear cluster {Pt_6}H_2 (2) contains a sterically hindered and chemically stable {Pt_6}=Pt _6-(μ-PtBu_2)_4(CO)_4 core, with the six metals forming an edge-bridged tetrahedron. The two hydrides are the reactive sites of the cluster and lie on opposite sides of the cluster, terminally bonded to the two "apical" edge-bridging platinum centres. Indeed, cluster 2 reacts with acids of different acidity (HA=CF _3SO_3H, HBF_4, p-CH_3-C _6H_4-SO_3H, CF_3COOH, PhCOOH and CH_3COOH), affording, after evolution of two equivalents of dihydrogen, the corresponding anion-substituted clusters {Pt_6}A _2 (4). We suggest that the reaction proceeds through a mechanism similar to the one generally accepted for the analogous protonation of mononuclear hydrides, with some of the intermediates partially characterised at low temperature. Interestingly, the reverse reaction, the heterolytic splitting of H_2 by clusters 4, occurs readily under mild conditions. The anions in clusters 4a and 4b (4a: A=CF_3SO_3, 4b: A=BF _4) are bonded in the solid state but very easily dissociate in solution and may be substituted under mild conditions by weak ligands, such as CH_2Cl_2 or CH_3CN. With dialkyl ethers, the reaction proceeds further with the heterolytic splitting of a C-H bond of the ethereal ligand. This process allowed us to isolate the polymer [{Pt _6}(CH_2OCH_2CH_2OCH_2)]x (8), in which the {Pt_6} cluster units are connected by insulating spacers arising from dimethoxyethane. The results of single-crystal X-ray diffraction studies on 4a and 8 are also reported.
机译：六核簇{Pt_6} H_2（2）包含空间受阻且化学稳定的{Pt_6} = Pt _6-（μ-PtBu_2）_4（CO）_4核，六种金属形成边桥四面体。这两个氢化物是团簇的反应性位点，位于团簇的相对两侧，末端键合到两个“顶部”边缘桥接的铂中心。实际上，簇2与不同酸度的酸（HA = CF _3SO_3H，HBF_4，p-CH_3-C _6H_4-SO_3H，CF_3COOH，PhCOOH和CH_3COOH）反应，在释放出两当量的二氢后，提供了相应的阴离子取代的簇{Pt_6} A _2（4）。我们建议反应是通过一种类似于单核氢化物的质子化普遍接受的机制进行的，其中一些中间体在低温下具有部分特征。有趣的是，在温和条件下很容易发生逆反应，即簇2对H_2的杂化分裂。簇4a和4b中的阴离子（4a：A = CF_3SO_3，4b：A = BF_4）以固态键合，但很容易在溶液中解离，在温和条件下可被弱配体（如CH_2Cl_2或CH_3CN）取代。对于二烷基醚，反应进一步进行，其中醚性配体的C-H键杂合裂解。此过程使我们能够分离出聚合物[{Pt _6}（CH_2OCH_2CH_2OCH_2）] x（8），其中{Pt_6}簇单元通过由二甲氧基乙烷产生的绝缘间隔基连接。还报告了在4a和8上进行单晶X射线衍射研究的结果。

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