Institut für Allgemeine, Anorganische und Theoretische Chemie der Universität Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.
Dalton Trans. 2012 Mar 28;41(12):3503-14. doi: 10.1039/c2dt11949h. Epub 2012 Feb 9.
In a novel template synthesis of carbodiphosphoranes (CDPs), the phosphine functionalized CDP ligand C(dppm)(2) (dppm = Ph(2)PCH(2)PPh(2)) is formed in the coordination sphere of group 10 metals from CS(2) and 4 equivalents of dppm. The products are the PCP pincer complexes [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Ni, Pd, Pt) and 2 equivalents of dppmS. The compound C(dppm)(2), which is composed of a divalent carbon atom and two dppm subunits, represents a new PCP-type pincer ligand with the formally neutral carbon Lewis base of the CDP functionality as the central carbon. Treatment of [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Pd, Pt) with hydrochloric acid results in protonation at the CDP carbon atom and the formation of the PCP pincer complexes [M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl(2) (M = Pd, Pt). The PCP pincer ligand CH(dppm)(2) involves a formally cationic central carbon donor. The reaction of [Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl with HCl leads to the extrusion of NiCl(2) and formation of the diprotonated CDP compound [CH(2)(dppm)(2)]Cl(2), from which the monoprotonated conjugate base [CH(dppm)(2)]Cl is obtained upon addition of bases, such as NH(3). The crystal structures of [M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl (M = Ni, Pd, Pt), Ni(Cl)(C(dppm)(2)-κ3P,C,P)[NiCl(4)], [M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl(2) (M = Pd, Pt) as well as [CH(2)(dppm)(2)]Cl(2) and [CH(dppm)(2)]Cl are presented. A comparison of the solid state structures reveals interesting features, e.g. infinite supramolecular networks mediated by C-H···Cl hydrogen bond interactions and an unexpected loss of molecular symmetry upon protonation in the complexes [M(CH(dppm)(2)-κ3P,C,P)(Cl)]Cl(2) (M = Pd, Pt) as a result of the flexible ligand backbone. Additionally the new compounds were characterized comprehensively in solution by multinuclear (31)P, (13)C and (1)H NMR spectroscopy: Several spectroscopic parameters show a striking variability in particular regarding the carbodiphosphorane functionality. Furthermore the compound [Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl was examined by cyclic voltammetry (CV) and could be shown to display quasi-reversible oxidative as well as reductive behaviour.
在一种新型的碳二膦（CDP）的模板合成中，从 CS2和 4 当量的二苯膦甲烷（dppm）出发，在第 10 族金属的配位球中形成了磷功能化的 CDP 配体 C(dppm)(2)。产物是 PCP 夹钳配合物[M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl（M = Ni、Pd、Pt）和 2 当量的二苯膦甲烷硫醚（dppmS）。C(dppm)(2)由一个二价碳原子和两个 dppm 亚基组成，代表了一种新的 PCP 型夹钳配体，其形式上中性的 CDP 官能团的碳路易斯碱作为中心碳。[M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl（M = Pd、Pt）与盐酸反应导致 CDP 碳原子质子化，形成 PCP 夹钳配合物[M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl2（M = Pd、Pt）。PCP 夹钳配体CH(dppm)(2)涉及一个形式上的带正电荷的中心碳供体。[Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl 与 HCl 的反应导致 NiCl2的挤出和二质子化 CDP 化合物[CH(2)(dppm)(2)]Cl2的形成，加入碱如 NH3后得到单质子化的共轭碱[CH(dppm)(2)]Cl。[M(Cl)(C(dppm)(2)-κ3P,C,P)]Cl（M = Ni、Pd、Pt）、Ni(Cl)(C(dppm)(2)-κ3P,C,P)[NiCl4]、[M(Cl)(CH(dppm)(2)-κ3P,C,P)]Cl2（M = Pd、Pt）以及[CH(2)(dppm)(2)]Cl2和[CH(dppm)(2)]Cl 的晶体结构均已呈现。对固态结构的比较揭示了有趣的特征，例如通过 C-H···Cl 氢键相互作用介导的无限超分子网络，以及在配合物[M(CH(dppm)(2)-κ3P,C,P)(Cl)]Cl2（M = Pd、Pt）中由于配体骨架的灵活性而导致质子化后分子对称性的意外丧失。此外，新化合物在溶液中通过多核（31）P、（13）C 和（1）H NMR 光谱进行了全面表征：几个光谱参数表现出显著的可变性，特别是关于碳二膦官能团。此外，通过循环伏安法（CV）对[Ni(Cl)(C(dppm)(2)-κ3P,C,P)]Cl 进行了检查，结果表明它显示出准可逆的氧化和还原行为。
