Bernhardt Eduard, Bach Christian, Bley Bianca, Wartchow Rudolf, Westphal Ulrich, Sham Iona H T, von Ahsen Britta, Wang Chanqing, Willner Helge, Thompson Robert C, Aubke Friedhelm
Institut für Anorganische Chemie der Universität Hannover, Callinstrasse 9, D-30167 Hannover, Germany.
Inorg Chem. 2005 Jun 13;44(12):4189-205. doi: 10.1021/ic040115u.
Homoleptic octahedral, superelectrophilic sigma-bonded metal carbonyl cations of the type M(CO)(6) (M = Ru, Os) are generated in the Bronsted-Lewis conjugate superacid HF/SbF(5) by reductive carbonylation of M(SO(3)F)(3) (M = Ru, Os) or OsF(6). Thermally stable salts form with either Sb(2)F(11) or SbF(6) as anion, just as for the previously reported Fe(CO)(6) cation. The latter salts are generated by oxidative (XeF(2)) carbonylation of Fe(CO)(5) in HF/SbF(5). A rationale for the two diverging synthetic approaches is provided. The thermal stabilities of [M(CO)(6)]SbF(6) salts, studied by DSC, range from 180 degrees C for M = Fe to 350 degrees C for M = Os before decarbonylation occurs. The two triads [M(CO)(6)]SbF(6) and [M(CO)(6)]Sb(2)F(11) (M = Fe, Ru, Os) are extensively characterized by single-crystal X-ray diffraction and vibrational and (13)C NMR spectroscopy, aided by computational studies of the cations. The three [M(CO)(6)]SbF(6) salts (M = Fe, Ru, Os) crystallize in the tetragonal space group P4/mnc (No. 128), whereas the corresponding Sb(2)F(11) salts are monoclinic, crystallizing in space group P2(1)/n (No. 14). In both triads, the unit cell parameters are nearly invariant of the metal. Bond parameters for the anions SbF(6) and Sb(2)F(11) and their vibrational properties in the two triads are completely identical. In all six salts, the structural and vibrational properties of the M(CO)(6) cations (M = Fe, Ru, Os) are independent of the counteranion and for the most part independent of M and nearly identical. Interionic C...F contacts are similarly weak in all six salts. Metal dependency is noted only in the (13)C NMR spectra, in the skeletal M-C vibrations, and to a much smaller extent in some of the C-O stretching fundamentals (A(1g) and T(1u)). The findings reported here are unprecedented among metal carbonyl cations and their salts.
通过M(SO₃F)₃（M = Ru、Os）或OsF₆的还原羰基化反应，在布朗斯特-路易斯共轭超强酸HF/SbF₅中生成了[M(CO)₆]²⁺（M = Ru、Os）这种类型的同配八面体超亲电σ键合金属羰基阳离子。与之前报道的[Fe(CO)₆]²⁺阳离子一样，它们与[Sb₂F₁₁]⁻或[SbF₆]⁻形成热稳定盐作为阴离子。后者的盐是通过Fe(CO)₅在HF/SbF₅中的氧化（XeF₂）羰基化反应生成的。文中给出了这两种不同合成方法的原理。通过差示扫描量热法（DSC）研究发现，[M(CO)₆][SbF₆]₂盐的热稳定性范围为：M = Fe时为180℃，M = Os时为350℃，之后才发生脱羰基反应。[M(CO)₆][SbF₆]₂和[M(CO)₆][Sb₂F₁₁]₂（M = Fe、Ru、Os）这两个三元组通过单晶X射线衍射、振动光谱和¹³C NMR光谱进行了广泛表征，并借助阳离子的计算研究辅助。三种[M(CO)₆][SbF₆]₂盐（M = Fe、Ru、Os）在四方空间群P4/mnc（编号128）中结晶，而相应的[Sb₂F₁₁]⁻盐是单斜晶系，在空间群P2₁/n（编号14）中结晶。在这两个三元组中，晶胞参数几乎与金属无关。[SbF₆]⁻和[Sb₂F₁₁]⁻阴离子的键参数及其在两个三元组中的振动性质完全相同。在所有六种盐中，[M(CO)₆]²⁺阳离子（M = Fe、Ru、Os）的结构和振动性质与抗衡阴离子无关，并且在很大程度上与M无关且几乎相同。在所有六种盐中，离子间的C…F接触同样较弱。仅在¹³C NMR光谱、骨架M - C振动中以及在较小程度上在一些C - O伸缩基频（A₁g和T₁u）中注意到金属依赖性。本文报道的这些发现对于金属羰基阳离子及其盐来说是前所未有的。
