Department of Chemistry, The University of Alabama , Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States.
Inorg Chem. 2014 Jan 6;53(1):446-56. doi: 10.1021/ic402422h. Epub 2013 Dec 17.
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.
激光烧蚀的镧系金属原子与过量的 OF2 在 4 K 下的氩气或氖气中冷凝。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，并将其分配给氧化加成产物 OLnF2 和 OLnF。在 500 cm(-1) 区域的主要吸收被确定为 Ln-F 伸缩模式，该模式遵循镧系收缩。Ln-O 伸缩频率是衡量 Ln 和氧的氧化态以及配合物的自旋态的重要指标。OCeF2、OPrF2 和 OTbF2 分子具有更高频率的 Ln-O 伸缩模式。Ce 被分配到 IV 氧化态，Pr 和 Tb 被分配到混合 III/IV 氧化态。其余的 OLnF2 化合物具有较低的 Ln-O 伸展，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，Ln-F 键是离子键。在 OCeF2、OLaF 和 OLuF 中，Ln 和 O 之间的键合最好描述为高度极化的 σ 键和由 O 上的两个 2p 孤对电子向 Ln 供体形成的两个伪 π 键。预测处于 III 氧化态的 OLnF2 化合物的键合完全是离子键。OLnF2 和 OLnF 的键合由镧系元素的氧化态和分子的自旋态主导。与它们的 OLnF2 类似物相比，几个 OLnF 分子的 Ln-O 模式的氖到氩基质位移较大，表明 OLnF 物种具有更多的离子特性，与 OLnF 中氧的更形式负电荷一致。
