Reactions of lanthanide atoms with oxygen difluoride and the role of the Ln oxidation state.
Reactions of lanthanide atoms with oxygen difluoride and the role of the Ln oxidation state.
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DOI：
10.1021/ic402422h
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发表时间：
2014-01
影响因子：
4.6
通讯作者：
Tanya C. Mikulas;Mingyang Chen;D. Dixon;K. Peterson;Yu Gong;L. Andrews
中科院分区：
文献类型：
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作者：
Tanya C. Mikulas;Mingyang Chen;D. Dixon;K. Peterson;Yu Gong;L. Andrews
激光烧蚀的镧系金属原子在4 K下与过量的氩气或氖中的OF 2凝聚。根据（18）O同位素取代和振动频率的电子结构计算，观察到新的红外吸收带，并将其归属于氧化加成产物OLnF 2和OLnF。在500 cm（-1）区域的主要伸缩模被确定为Ln-F伸缩模，它遵循镧系收缩。Ln-O伸缩频率是衡量Ln和氧的氧化态以及配合物自旋态的重要尺度。OCeF 2、OPrF 2和OTbF 2分子具有较高频率的Ln-O伸缩模。Ce被分配为IV氧化态，Pr和Tb被分配为混合的III/IV氧化态。其余的OLnF 2化合物具有较低的Ln-0伸缩，并且Ln处于III氧化态，O处于-1氧化态。对于所有的OLnF化合物，金属处于III氧化态，并且Ln-F键是离子的。在OCeF 2、OLaF和OLuF中，Ln和O之间的键合最好描述为高度极化的σ键和两个由O上的两个2 p孤对向Ln的捐赠形成的伪π键。预测处于III氧化态的OLnF 2化合物的键合是完全离子化的。OLnF 2和OLnF中的成键由镧系元素上的氧化态和分子的自旋态主导。与OLnF 2类似物相比，在几种OLnF分子中观察到Ln-O模式的较大氖-氩矩阵位移表明OLnF物质中的离子特征更多，这与OLnF中氧上的更正式的负电荷一致。
Laser-ablated lanthanide metal atoms were condensed with OF2 in excess argon or neon at 4 K. New infrared absorption bands were observed and assigned to the oxidative addition products OLnF2 and OLnF on the basis of (18)O isotopic substitution and electronic structure calculations of the vibrational frequencies. The dominant absorptions in the 500 cm(-1) region are identified as Ln-F stretching modes, which follow the lanthanide contraction. The Ln-O stretching frequency is an important measure of the oxidation states of the Ln and oxygen and the spin state of the complex. The OCeF2, OPrF2, and OTbF2 molecules have higher frequency Ln-O stretching modes. The Ce is assigned to the IV oxidation state and the Pr and Tb are assigned to a mixed III/IV oxidation state. The remaining OLnF2 compounds have lower Ln-O stretches, and the Ln is in the III oxidation state and the O is in the -1 oxidation state. For all of the OLnF compounds, the metal is in the III oxidation state, and the Ln-F bonds are ionic. In OCeF2, OLaF, and OLuF, the bonding between the Ln and O is best described as a highly polarized σ bond and two pseudo π bonds formed by donation from the two 2p lone pairs on the O to the Ln. Bonding for the OLnF2 compounds in the III oxidation state is predicted to be fully ionic. The bonding in OLnF2 and OLnF is dominated by the oxidation state on the lanthanide and the spin state of the molecule. The observation of larger neon to argon matrix shifts for Ln-O modes in several OLnF molecules as compared to their OLnF2 analogues is indicative of more ionic character in the OLnF species, consistent with the more formal negative charge on the oxygen in OLnF.