Linear, redox-active Pt6 and Pt2Pd2Pt2 clusters.
Linear, redox-active Pt6 and Pt2Pd2Pt2 clusters.
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DOI：
10.1002/anie.200460707
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发表时间：
2004-09
影响因子：
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通讯作者：
Eri Goto;R. Begum;Shu-zhong Zhan;T. Tanase;K. Tanigaki;K. Sakai
中科院分区：
文献类型：
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作者：
Eri Goto;R. Begum;Shu-zhong Zhan;T. Tanase;K. Tanigaki;K. Sakai
过渡金属簇合物是一种具有多种几何结构的多核金属簇合物，由于其丰富的化学和物理性质以及在单个分子中整合多种功能的潜力而受到越来越多的关注。[1]特别是，显示线性金属-金属键合的团簇已被视为开发纳米结构材料，包括分子电子，光学和化学器件的有前途的候选人。然而，使用金属原子的自组装的合成方法通常导致多面体簇核，因此具有线性金属聚集体的分子的路线是有限的。[2-7]研究了三齿膦配体双（二苯基膦基甲基）苯基膦（dpmp）负载的同、异金属双核和三核配合物。[8]通过在双铂配合物[Pt 2（μ-dpmp）2（XylNC）2]（PF 6）2中选择性引入零价Pt或Pd原子，合成了线性有序的三核配合物[Pt 2 M（μ-dpmp）2（XylNC）2]（PF 6）2（M= Pt（1a），Pd（1b）; Xyl= 2，6-二甲基苯基）. [8c]在本研究中，我们已经研究了一个集群核心扩展1，并成功地合成了线性六金属簇含有氧化还原活性的Pt 2 M2 Pt 2金属串（M= Pt，Pd）。当线性三铂络合物1a用过量的NaBH 4在乙醇中处理，并且所得棕色沉淀被萃取并在CH 2Cl 2中搅拌时，以良好的产率分离深蓝色抗磁性六铂簇[Pt 6（μ-H）（μ-dpmp）4-（XylNC）2]（PF 6）3（2）（方案1）。虽然Pt 2 Pd三核配合物1b不能用NaBH 4展开，但它容易与NaOMe在CH 2Cl 2/MeOH中反应，得到深绿色晶体[Pt 4Pd 2（μ-H）（μ-dpmp）4（XylNC）2]（PF 6）3（3，方案1）。在形成2型的反应过程中，ESI质谱和电子吸收光谱的变化表明，初始棕色化合物（指定为[Pt 3（H）2（μdpmp）2（XylNC）] 2+（A））在CH 2Cl 2中迅速转化为[Pt 3（H）（μdpmp）2（XylNC）]+（B）。据推测，一氢化物中间体B经历偶联和伴随的部分氧化以生成络合物2。然而，没有鉴定出中间种属。[9]通过X射线衍射分析确定了2的晶体结构。[10]团簇阳离子2的电荷为+3，团簇价电子数（CVE）为86。它由六个线性排列的铂原子（Pt-Pt-Pt 174.87（2）-179.67（2）8）组成，由四个dpmp配体桥接，并由两个异氰化物分子封端（图1）。Pt 6团簇核具有赝C2对称性，外Pt 1 <$Pt2和Pt 5 <$Pt6键的平均Pt <$Pt距离（dout）为2.7041 <$$>，内Pt 2 <$Pt3和Pt 4 <$Pt5键的平均Pt <$Pt距离（dinn）为2.7329 <$，中心Pt 3 <$Pt4键的平均Pt <$Pt距离（dcen）为3.3092（5）<$。dout和dinn的值与三铂络合物1 [8]的值相当，表明存在Pt <$Pt σ键。虽然中心的两个铂原子不支持任何有机配体，并在空间上很好地保护的dpmp配体的四个苯基基团，非常长的距离dcen表明存在的桥接氢化物，这是明确证实了1H NMR光谱。
Transition metal clusters, which contain multinuclear metal sites connected by metal–metal bonds in a variety of geometrical structures, have attracted increasing attention due to their versatile chemical and physical properties as well as their potential to integrate multiple functions in a single molecule.[1] In particular, clusters that show linear metal–metal bonding have been regarded as promising candidates in developing nanostructured materials including molecular electronic, optical, and chemical devices. However, synthetic methods using self-assembly of metal atoms often lead to polyhedral cluster cores, and thus routes to molecules with linear metal aggregations are limited.[2–7] We have studied homo-and heterometallic dinuclear and trinuclear complexes supported by the tridentate phosphane ligand bis (diphenylphosphanylmethyl) phenylphosphane (dpmp).[8] The linearly ordered trinuclear complexes[Pt2M (μdpmp) 2 (XylNC) 2](PF6) 2 (M= Pt (1a), Pd (1b); Xyl= 2, 6-dimethylphenyl) were prepared by site-selective incorporation of a zero-valent Pt or Pd atom into the diplatinum complex [Pt2 (μ-dpmp) 2 (XylNC) 2](PF6) 2.[8c] In the present study, we have examined a cluster core expansion of 1, and have successfully synthesized linear hexametallic clusters containing a redox-active Pt2M2Pt2 metal string (M= Pt, Pd). When the linear triplatinum complex 1a was treated with excess NaBH4 in ethanol, and the resultant brown precipitate was extracted and stirred in CH2Cl2, the dark blue, diamagnetic hexaplatinum cluster [Pt6 (μ-H)(μ-dpmp) 4-(XylNC) 2](PF6) 3 (2) was isolated in good yield (Scheme 1).Compound 2 was also obtained in low yield from the reaction of 1 with NaOMe. Although the Pt2Pd trinuclear complex 1b failed to be expanded with NaBH4, it readily reacted with NaOMe in CH2Cl2/MeOH to afford dark green crystals of [Pt4Pd2 (μ-H)(μ-dpmp) 4 (XylNC) 2](PF6) 3 (3, Scheme1). The changes in the ESI mass spectrum and the electronic absorption spectrum during the reaction to form 2 indicated that the initial brown compound, assigned as [Pt3 (H) 2 (μdpmp) 2 (XylNC)] 2+(A), was rapidly converted into [Pt3 (H)(μdpmp) 2 (XylNC)]+(B) in CH2Cl2. It is assumed that the monohydride intermediate B undergoes coupling and concomitant partial oxidation to generate complex 2. However, the intervening species were not identified.[9] The crystal structure of 2 was determined by X-ray analysis.[10] The cluster cation of 2 has a charge of+ 3 with a cluster valence electron count (CVE) of 86. It consists of six linearly ordered platinum atoms (Pt-Pt-Pt 174.87 (2)–179.67 (2) 8) bridged by four dpmp ligands and terminated by two isocyanide molecules (Figure 1). The Pt6 cluster core has a pseudo C2 symmetry, and the average Pt¿ Pt distances are 2.7041 ä for the outer Pt1¿ Pt2 and Pt5¿ Pt6 bonds (dout), 2.7329 ä for the inner Pt2¿ Pt3 and Pt4¿ Pt5 bonds (dinn), and 3.3092 (5) ä for the central Pt3¿ Pt4 bond (dcen). The values for dout and dinn are comparable to those of the triplatinum complex 1 [8] and indicate the presence of Pt¿ Pt σ bonds. Although the two central platinum atoms are not supported by any organic ligands and are sterically well protected by the four phenyl groups of the dpmp ligands, the remarkably long distance dcen indicates the presence of a bridging hydride; this was unambiguously confirmed by 1H NMR spectroscopy.