Yamazaki Emi, Okabayashi Toshiaki, Tanimoto Mitsutoshi
Department of Chemistry, Faculty of Science, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan.
J Am Chem Soc. 2004 Feb 4;126(4):1028-9. doi: 10.1021/ja0391309.
Unsaturated transition metal carbonyls are important in processes such as organometallic synthesis, homogeneous catalysis, and photochemical decomposition of organometallics. In particular, a metal monocarbonyl offers a zeroth-order model for interpreting the chemisorption of a CO molecule on a metal surface in catalytic activation processes. Quite large numbers of theoretical papers have appeared which predict spectroscopic and structural properties of transition metal carbonyls. The nickel monocarbonyl NiCO has been one of the metal carbonyls most extensively studied by the theoretical calculations. At least 50 theoretical studies have been published on this simplest transition metal carbonyl up to the present time. However, experimental evidence of NiCO is much more sparse than theoretical predictions, and the actual structure of NiCO has never been determined by any experimental methods. This Communication reports the first preparation of free nickel monocarbonyl and observation of its rotational transitions. The NiCO molecule was generated by the sputtering reaction of a Ni cathode in the presence of CO. The accurate bond lengths of Ni-C and C-O were experimentally determined from isotopic data and were compared with the theoretical predictions for the first time.
不饱和过渡金属羰基化合物在有机金属合成、均相催化以及有机金属化合物的光化学分解等过程中具有重要意义。特别是，金属单羰基化合物为解释催化活化过程中CO分子在金属表面的化学吸附提供了零级模型。已经出现了大量预测过渡金属羰基化合物光谱和结构性质的理论论文。单羰基镍NiCO一直是理论计算研究最为广泛的金属羰基化合物之一。截至目前，关于这种最简单的过渡金属羰基化合物已发表了至少50项理论研究。然而，NiCO的实验证据比理论预测要少得多，并且NiCO的实际结构从未通过任何实验方法确定。本通讯报道了游离单羰基镍的首次制备及其转动跃迁的观测。NiCO分子是通过在CO存在下镍阴极的溅射反应生成的。通过同位素数据实验测定了Ni-C和C-O的精确键长，并首次与理论预测进行了比较。
