Plundrich Gudrun T, Wadepohl Hubert, Clot Eric, Gade Lutz H
Anorganisch Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM-ENSCM, Université de Montpellier, cc 1501, Place Eugène Bataillon, 34095, Montpellier Cedex 5, France.
Chemistry. 2016 Jun 27;22(27):9283-92. doi: 10.1002/chem.201601213. Epub 2016 Jun 3.
The cyclometalated monobenzyl complexes [(Cbzdiphos(R) -CH)ZrBnX] 1 (iPr) Cl and 1 (Ph) I reacted with dihydrogen (10 bar) to yield the η(6) -toluene complexes [(Cbzdiphos(R) )Zr(η(6) -tol)X] 2 (iPr) Cl and 2 (Ph) I (cbzdiphos=1,8-bis(phosphino)-3,6-di-tert-butyl-9H-carbazole). The arene complexes were also found to be directly accessible from the triiodide [(Cbzdiphos(Ph) )ZrI3 ] through an in situ reaction with a dibenzylmagnesium reagent and subsequent hydrogenolysis, as exemplified for the η(6) -mesitylene complex [(Cbzdiphos(Ph) )Zr(η(6) -mes)I] (3 (Ph) I). The tolyl-ring in 2 (iPr) Cl adopts a puckered arrangement (fold angle 23.3°) indicating significant arene-1,4-diido character. Deuterium labeling experiments were consistent with an intramolecular reaction sequence after the initial hydrogenolysis of a Zr-C bond by a σ-bond metathesis. A DFT study of the reaction sequence indicates that hydrogenolysis by σ-bond metathesis first occurs at the cyclometalated ancillary ligand giving a hydrido-benzyl intermediate, which subsequently reductively eliminates toluene that then coordinates to the Zr atom as the reduced arene ligand. Complex 2 (Ph) I was reacted with 2,6-diisopropylphenyl isocyanide giving the deep blue, diamagnetic Zr(II) -diisocyanide complex [(Cbzdiphos(Ph) )Zr(CNDipp)2 I] (4 (Ph) I). DFT modeling of 4 (Ph) I demonstrated that the HOMO of the complex is primarily located as a "lone pair on zirconium", with some degree of back-bonding into the C≡N π* bond, and the complex is thus most appropriately described as a zirconium(II) species. Reaction of 2 (Ph) I with trimethylsilylazide (N3 TMS) and 2 (iPr) Cl with 1-azidoadamantane (N3 Ad) resulted in the formation of the imido complexes [(Cbzdiphos(R) )Zr=NR'(X)] 5 (iPr) Cl-NAd and 5 (Ph) I-NTMS, respectively. Reaction of 2 (iPr) Cl with azobenzene led to N-N bond scission giving 6 (iPr) Cl, in which one of the NPh-fragments is coupled with the carbazole nitrogen to form a central η(2) -bonded hydrazide(-1), whereas the other NPh-fragment binds to zirconium acting as an imido-ligand. Finally, addition of pyridine to 2 (iPr) Cl yielded the dark purple complex [(Cbzdiphos(iPr) )Zr(bpy)Cl] (7 (iPr) Cl) through a combination of CH-activation and C-C-coupling. The structural data and UV/Vis spectroscopic properties of 7 (iPr) Cl indicate that the bpy (bipyridine) may be regarded as a (dianionic) diamido-type ligand.
环金属化单苄基配合物[(Cbzdiphos(R)-CH)ZrBnX] 1 (iPr)Cl和1 (Ph)I与氢气（10 bar）反应生成η(6)-甲苯配合物[(Cbzdiphos(R))Zr(η(6)-tol)X] 2 (iPr)Cl和2 (Ph)I（cbzdiphos = 1,8-双(膦基)-3,6-二叔丁基-9H-咔唑）。还发现芳烃配合物可通过三碘化物[(Cbzdiphos(Ph))ZrI3]与二苄基镁试剂原位反应并随后进行氢解直接得到，例如η(6)-均三甲苯配合物[(Cbzdiphos(Ph))Zr(η(6)-mes)I]（3 (Ph)I）。2 (iPr)Cl中的甲苯环呈褶皱排列（折叠角23.3°），表明具有显著的芳烃-1,4-二碘特征。氘标记实验与通过σ键复分解对Zr-C键进行初始氢解后的分子内反应序列一致。对反应序列的密度泛函理论（DFT）研究表明，通过σ键复分解进行的氢解首先发生在环金属化辅助配体上，生成氢化苄基中间体，随后该中间体经还原消除甲苯，甲苯再作为还原的芳烃配体与Zr原子配位。配合物2 (Ph)I与2,6-二异丙基苯基异氰酸酯反应生成深蓝色的抗磁性Zr(II)-二异氰酸酯配合物[(Cbzdiphos(Ph))Zr(CNDipp)2I]（4 (Ph)I）。4 (Ph)I的DFT建模表明，该配合物的最高占据分子轨道（HOMO）主要定位为“锆上的孤对电子”，并对C≡N π*键有一定程度的反馈键合，因此该配合物最适合描述为锆(II)物种。2 (Ph)I与三甲基硅叠氮化物（N3TMS）反应以及2 (iPr)Cl与1-叠氮基金刚烷（N3Ad）反应分别生成亚胺基配合物[(Cbzdiphos(R))Zr=NR'(X)] 5 (iPr)Cl-NAd和5 (Ph)I-NTMS。2 (iPr)Cl与偶氮苯反应导致N-N键断裂生成6 (iPr)Cl，其中一个NPh片段与咔唑氮原子偶联形成中心η(2)-键合的酰肼(-1)，而另一个NPh片段作为亚胺基配体与锆结合。最后，向2 (iPr)Cl中加入吡啶通过CH活化和C-C偶联生成深紫色配合物[(Cbzdiphos(iPr))Zr(bpy)Cl]（7 (iPr)Cl）。7 (iPr)Cl的结构数据和紫外/可见光谱性质表明，联吡啶（bpy）可被视为一种（双阴离子）二酰胺型配体。
