Kapteijn Gerardus M., Grove David M., Kooijman Huub, Smeets Wilberth J. J., Spek Anthony L., van Koten Gerard
Department of Metal-Mediated Synthesis, Debye Institute, and Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Inorg Chem. 1996 Jan 17;35(2):526-533. doi: 10.1021/ic950563p.
Reaction of palladium acetate with 2 equiv of sodium phenoxide in the presence of a chelate diamine ligand affords the complexes [Pd(OPh)(2)(N approximately N)] (N approximately N = bpy (1), tmeda (2), teeda (3), dpe (4), dmap (5)). These yellow to orange bis(phenoxo)palladium(II) complexes are thermally stable at room temperature in the solid state as well as in solution. Addition of an excess of pentafluorophenol to 1, 2, 4, and 5 affords crystalline complexes [Pd(OC(6)F(5))(2)(N approximately N)] (N approximately N = bpy (6), tmeda (7), dpe (8), dmap (9)). Crystals of 1 and 6 have been subjected to X-ray diffraction studies. Crystals of 1 are orthorhombic, space group P2(1)2(1)2(1) (no. 19), with a = 6.7655(6) Å, b = 16.0585(10) Å, c = 16.7275(13) Å, and Z = 4. Crystals of 6 are triclinic, space group P&onemacr; (no. 2), with a = 7.567(4) Å, b = 12.708(3) Å, c = 12.912(5) Å, alpha = 61.51(3) degrees, beta = 74.74(4) degrees, gamma = 88.78(4) degrees, and Z = 2. The molecular structures of 1 and 6 show them to be square-planar complexes, and the main structural difference between these complexes is the orientation of the aromatic rings. In 6 the OC(6)F(5) ligands are almost parallel in a face-to-face orientation (pi-pi stacking interactions), whereas in 1 the OC(6)H(5) units are skewed away from each other. An unexpected "mixed" alkoxo(aryloxo) complex [Pd(OCH(CF(3))(2))(OPh)(bpy)].HOPh (10) is formed when 1 is reacted with 1,1,1,3,3,3-hexafluoro-2-propanol. The molecular structure of 10 shows O-H.O hydrogen bonding (O.O = 2.642(8) Å) between the hydroxyl hydrogen of phenol and the oxygen atom of the phenoxide ligand as well as an additional C-H.O contact (C.O) = 2.95(1) Å), which can be regarded as the initial stage of a base-assisted beta-hydrogen elimination. Crystals of 10 are monoclinic, space group P2(1)/c, with a = 8.3241(14) Å, b = 11.0316(17) Å, c = 26.376(3) Å, alpha = 93.01(1) degrees, Z = 4. Spectroscopic data of complexes 1-10 indicate that the oxygen atom of the aryloxide or alkoxide ligand is extremely electron-rich, leading to high polarization of the palladium-to-oxygen bond. The bis(phenoxide) complexes 1, 2, and 4 associate with two molecules of phenol through O-H.O hydrogen bonds to form adducts [Pd(OPh)(2)(N approximately N)].2HOPh (N approximately N = bpy (11), tmeda (12), dpe (13)). The palladium complexes 6-9 with OC(6)F(5) groups show no tendency to form adducts with alcohols.
乙酸钯与2当量苯氧钠在螯合二胺配体存在下反应，得到配合物[Pd(OPh)₂(N≈N)]（N≈N = 联吡啶（1）、四甲基乙二胺（2）、四乙基乙二胺（3）、二苯醚（4）、4,4'-二甲基氨基吡啶（5））。这些黄色至橙色的双（苯氧基）钯（II）配合物在室温下于固态以及溶液中均热稳定。向1、2、4和5中加入过量的五氟苯酚，得到晶体配合物[Pd(OC₆F₅)₂(N≈N)]（N≈N = 联吡啶（6）、四甲基乙二胺（7）、二苯醚（8）、4,4'-二甲基氨基吡啶（9））。对1和6的晶体进行了X射线衍射研究。1的晶体为正交晶系，空间群P2₁2₁2₁（编号19），a = 6.7655(6) Å，b = 16.0585(10) Å，c = 16.7275(13) Å，Z = 4。6的晶体为三斜晶系，空间群Pī（编号2），a = 7.567(4) Å，b = 12.708(3) Å，c = 12.912(5) Å，α = 61.51(3)°，β = 74.74(4)°，γ = 88.78(4)°，Z = 2。1和6的分子结构表明它们是平面正方形配合物，这些配合物之间的主要结构差异在于芳环的取向。在6中，OC₆F₅配体几乎以面对面的取向平行排列（π-π堆积相互作用），而在1中，OC₆H₅单元相互错开。当1与1,1,1,3,3,3-六氟-2-丙醇反应时，形成了一个意外的“混合”烷氧基（芳氧基）配合物[Pd(OCH(CF₃)₂)(OPh)(bpy)].HOPh（10）。10的分子结构显示苯酚的羟基氢与苯氧基配体的氧原子之间存在O-H.O氢键（O.O = 2.642(8) Å）以及额外的C-H.O接触（C.O = 2.95(1) Å），这可被视为碱辅助β-氢消除的初始阶段。10的晶体为单斜晶系，空间群P2₁/c，a = 8.3241(14) Å，b = 11.0316(17) Å，c = 26.376(3) Å，α = 93.01(1)°，Z = 4。配合物1 - 10的光谱数据表明，芳氧基或烷氧基配体的氧原子电子云密度极高，导致钯 - 氧键高度极化。双（苯氧基）配合物1、2和4通过O-H.O氢键与两分子苯酚缔合，形成加合物[Pd(OPh)₂(N≈N)].2HOPh（N≈N = 联吡啶（11）、四甲基乙二胺（12）、二苯醚（13））。带有OC₆F₅基团的钯配合物6 - 9没有与醇形成加合物的倾向。
