Finze Maik, Bernhardt Eduard, Willner Helge, Lehmann Christian W, Aubke Friedhelm
FB C-Anorganische Chemie, Bergische Universität Wuppertal, Gaussstrasse 20, D-42097 Wuppertal, Germany.
Inorg Chem. 2005 Jun 13;44(12):4206-14. doi: 10.1021/ic0482483.
As the first examples of homoleptic, sigma-bonded superelectrophilic metal carbonyl cations with tetrafluoroborate BF(4) as the counter anions three thermally stable salts of the composition [M(CO)(6)]BF(4) (M = Fe, Ru, Os) have been synthesized and extensively characterized by thermochemical, structural, and spectroscopic methods. A common synthetic route, the oxidative carbonylation of either Fe(CO)(5) (XeF(2) as the oxidizer) or M(3)(CO)(12) (M = Ru, Os) (F(2) as the oxidizer) in the conjugate Bronsted-Lewis superacid HF/BF(3), was employed. The thermal behavior of the three salts, studied by differential scanning calorimetry (DSC) and gas-phase IR spectroscopy of the decomposition products, has been compared to that of the corresponding SbF(6) salts. The molecular structures of [M(CO)(6)]BF(4) (M = Fe, Os) were obtained by single-crystal X-ray diffraction at 100 K. X-ray powder diffraction data for [M(CO)(6)]BF(4) (M = Ru, Os) were obtained between 100 and 300 K in intervals of 50 K. All three salts are isostructural and crystallized in the tetragonal space group I4/m (No. 87). As for the corresponding [M(CO)(6)]SbF(6) salts (M = Fe, Ru, Os), similar unit cell parameters and vibrational fundamentals were also found for the three BF(4) compounds. For the structurally characterized salts [M(CO)(6)]BF(4) (M = Fe, Os), very similar bond parameters for both cations and anions were found. Hence, the invariance of structural and spectroscopic properties of M(CO)(6) cations (M = Fe, Ru, Os) extended from the fluoroantimonates Sb(2)F(11) and SbF(6) as counteranions also to BF(4).
作为首例以四氟硼酸根[BF(4)]⁻为抗衡阴离子的同配体、σ键合超亲电金属羰基阳离子，合成了三种组成为[M(CO)₆][BF(4)]₂（M = Fe、Ru、Os）的热稳定盐，并通过热化学、结构和光谱方法对其进行了广泛表征。采用了一种常见的合成路线，即在共轭布朗斯特-路易斯超酸HF/BF₃中，使Fe(CO)₅（以XeF₂为氧化剂）或M₃(CO)₁₂（M = Ru、Os，以F₂为氧化剂）进行氧化羰基化反应。通过差示扫描量热法（DSC）和对分解产物进行气相红外光谱研究了这三种盐的热行为，并与相应的[SbF(6)]⁻盐的热行为进行了比较。[M(CO)₆][BF(4)]₂（M = Fe、Os）的分子结构通过在100 K下的单晶X射线衍射获得。[M(CO)₆][BF(4)]₂（M = Ru、Os）的X射线粉末衍射数据在100至300 K之间以50 K的间隔获得。所有这三种盐都是同构的，并且在四方空间群I4/m（编号87）中结晶。至于相应的[M(CO)₆][SbF(6)]₂盐（M = Fe、Ru、Os），在这三种[BF(4)]⁻化合物中也发现了相似的晶胞参数和振动基频。对于结构已表征的盐[M(CO)₆][BF(4)]₂（M = Fe、Os），发现阳离子和阴离子的键参数非常相似。因此，[M(CO)₆]²⁺阳离子（M = Fe、Ru、Os）的结构和光谱性质的不变性从作为抗衡阴离子的氟锑酸盐[Sb₂F₁₁]⁻和[SbF(6)]⁻扩展到了[BF(4)]⁻。
