4f Orbital Covalence in (η 5 -C 5 H 5 ) 3 Eu(THF) as Revealed by Europium-151 Mössbauer Spectroscopy
4f Orbital Covalence in (η 5 -C 5 H 5 ) 3 Eu(THF) as Revealed by Europium-151 Mössbauer Spectroscopy
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由 Europium-151 穆斯堡尔谱揭示的 (η 5 -C 5 H 5 ) 3 Eu(THF) 中的 4f 轨道共价
DOI：
10.1021/ja00092a073
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发表时间：
1994
影响因子：
15
通讯作者：
G. Long
中科院分区：
文献类型：
--
作者：
G. Depaoli;U. Russo;G. Valle;F. Grandjean;Alan F. Williams;G. Long
镧系元素配位和有机金属化学的范例之一是4f轨道被强烈屏蔽而不与配体相互作用。本文首次报道了（7_5-C_5H_5）_3Eu（THF）中配体与铕4f轨道强共价键相互作用的实验证据。铕-151穆斯堡尔谱是测定有机铕化合物电子性质的优良探针。2铕-151异构体位移强烈地依赖于铕的价态，并且铕（II）化合物通常具有约-3的异构体位移。12.5 mm/s。相比之下，铕（III）化合物具有约2 -4的异构体位移。0.3 mm/s。用四极相互作用研究了铕-151核的立方对称结构畸变的程度。大多数有机铕化合物2 -4显示小于±15 mm/s的小四极相互作用，并且在Eui中显示+ 48 mm/s的四极相互作用。o3Rh3B2。i是有史以来最大的。[5]在此，我们报道了（t^-CsHsjEuClr（THF）3的晶体结构和几种新的有机铕（III）化合物在各种配体环境下的铕-151穆斯堡尔谱。一种化合物（t_5-C_5H_5）_3Eu（THF）是不寻常的，因为它同时表现出非常负的异构体位移（-1.77 mm/s）和非常大的负四极相互作用（-33.6 mm/s）。这些值是唯一的thosebed 2 -4为有机铕（III）化合物，并讨论了该化合物的电子结构。所有有机金属化合物均在严格排除空气和水分的氮气气氛手套箱中制备和处理。根据标准方法6干燥溶剂THF和戊烷，并在使用前立即在氮气下蒸馏。根据标准方法制备无水EuCl 3和环戊二烯钠。7· 8（i？5-C5 H5）EuCl 2（THF）3和（j？5-C5 H5）3Eu（THF）如前所述制备。9-11*（i？5-<$5H5）Eu（NCS）2（THF）3是（1）（a）帕多瓦大学，（B）列日大学。(c)日内瓦大学，（d）密苏里-罗拉大学。(2)Grandjean，F.;穆斯堡尔谱学在无机化学中的应用。J.，Grandjean，F.，编辑; Plenum Press：纽约，1989年;第3卷，第513 -597页。
One of the paradigms of lanthanide coordination and organo-metallic chemistry is that the 4f orbitals are strongly shielded from interaction with the ligands. Thepurpose of this com-munication is to report the first, to our knowledge, experimental evidence for a strong covalent bonding interaction of ligands with the 4f orbitals of europium in (7j5-C5H5) 3Eu (THF). Europium-151 Móssbauer spectroscopy is an excellent probe for determining the electronic properties of organoeuropium compounds. 2 The europium-151 isomer shift is strongly dependent upon the valence state of europium, and europium (II) compounds typically have3 isomer shifts of ca.-12.5 mm/s. In contrast, europium (III) compounds have isomer shifts2-4 of ca. 0.3 mm/s. The extent of structural distortion from cubic symmetry at the europium-151 nucleus is probed by the quadrupole interaction. Most organoeuropium compounds2-4 show small quadrupole interactions of less than±15 mm/s, and the quadrupole interaction of+ 48 mm/s in Eui. o3Rh3B2. i is the largest ever reported. 5 Herein, we report the crystal structure of (t^-CsHsjEuClr (THF) 3 and the europium-151 Móssbauer spectra of several new organoeuropium (III) compounds with a variety of ligand environments. One compound,(tj5-C5Hs) 3Eu (THF), is unusual because it exhibits both a very negative isomer shift of-1.77 mm/s and a very large negative quadrupole interaction of-33.6 mm/s. These values are unique among thoseobserved2-4 for organoeuropium (III) compounds and are discussed in terms of the electronic structure of this compound. All organometallic compounds were prepared and handled in a nitrogen atmosphere glovebox with rigorous exclusion of air and moisture. The solvents, THF and pentane, were dried according to standard methods6 and distilled under nitrogen immediately prior to use. Anhydrous EuC13 and sodium cyclopentadienide were prepared according to standard methods. 7· 8 (i? 5-C5H5) EuC12 (THF) 3 and (j? 5-C5H5) 3Eu (THF) were prepared as reported previously. 9-11*(i? 5-¿ 5H5) Eu (NCS) 2 (THF) 3 was (1)(a) Universitá di Padova,(b) Université de Liége.(c) University of Geneva,(d) University of Missouri—Rolla.(2) Grandjean, F.; Long, GJ In Móssbauer Spectroscopy Applied to Inorganic Chemistry·, Long, G. J., Grandjean, F., Eds.; Plenum Press: New York, 1989; Vol. 3, pp513-597.