Synthesis of [2]ferrocenophanes containing trivalent diphosphine units
Synthesis of [2]ferrocenophanes containing trivalent diphosphine units
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DOI：
10.1016/j.jorganchem.2012.04.022
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发表时间：
2012-08-15
影响因子：
2.3
通讯作者：
Mizuta, Tsutomu
中科院分区：
文献类型：
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作者：
Tanimoto, Yoshikazu;Ishizu, Yuko;Mizuta, Tsutomu
通过镁介导的相应[Fe{C5H4P(Cl)R}(2)]磷中心之间的还原偶联合成了三种(PR)(2)-桥联[2]二茂铁（R = Bu-t (10a)、Bu-n (10b) 和 Ph (10c)），其中二茂铁单元的两个 C5H4 环通过 P(III)-P(III) 键桥接。 [Fe{C5H4P(Cl)R}(2)]的P(Cl)R基团由[Fe{C5H4P(NEt2)(2)}(2)]的P(NEt2)(2)基团衍生如下：P(NEt2)(2)基团首先通过HCl转化为P(Cl)NEt2，然后引入R(R = Bu-t、Bu-n和Ph)，得到P(R)NEt2，再次与 HCl 反应形成 P(Cl) R 基团。在三种二磷[2]二膦中，((PBu)-Bu-t)(2)-桥联[2]二茂铁 (10a) 可以作为游离二膦分离，而由于难以作为游离配体分离，Bu-n 和 Ph 类似物（分别为 10b 和 10c）被表征为双（五羰基金属）络合物(mu-10b)-[W(CO)(5)](2) (11) 和 (mu-10c)-[Cr(CO)(5)](2) (12)，其中各自的磷中心与五羰基金属片段配位。对三种二磷[2]二茂铁10a、11和12进行X射线分析，证明它们的P-P键长分别为2.3093(7)、2.261(5)和2.2502(8)埃。因为这些系链P-P长度小于二茂铁的两个平行C5H5环之间的理想距离，所以10a、11和12中的每一个的两个C5H4环分别从平行线倾斜12.9度、9.7度和13.6度。以(PH)(2)-桥联[2]二茂铁作为模型化合物进行DFT计算，结果表明存在两种构象异构体。一种称为平行形式，其 P-P 键几乎平行于穿过两个 C5H4 环中心的轴，而另一种称为扭曲形式，其 P-P 键随着两个 C5H4 环的扭曲而倾斜。 11 观察到的 9.7 度的较小倾斜角是由于其平行构象造成的，而 10a 和 12 的 C5H4 环由于采用扭曲构象而更加倾斜。 (C) 2012 Elsevier B.V. 保留所有权利。
Three (PR)(2)-bridged [2]ferrocenophanes (R = Bu-t (10a), Bu-n (10b), and Ph (10c)) in which the two C5H4 rings of the ferrocene unit were bridged with a P(III)-P(III) bond were synthesized via Mg-mediated reductive coupling between the phosphorus centers of corresponding [Fe{C5H4P(Cl)R}(2)]. The P(Cl)R groups of [Fe{C5H4P(Cl)R}(2)] were derived from the P(NEt2)(2) groups of [Fe{C5H4P(NEt2)(2)}(2)] as follows: the P(NEt2)(2) group was first converted to P(Cl)NEt2 by HCl, and then R (R = Bu-t, Bu-n, and Ph) was introduced to give P(R)NEt2, which was again allowed to react with HCl to form the P(Cl) R group. Of the three diphospha[2]ferrocenophanes, ((PBu)-Bu-t)(2)-bridged [2]ferrocenophane (10a) could be isolated as free diphosphine, while because of difficulty in their isolations as free ligands, the Bu-n and Ph analogs (10b and 10c, respectively) were characterized as bis(pentacarbonylmetal) complexes (mu-10b)-[W(CO)(5)](2) (11) and (mu-10c)-[Cr(CO)(5)](2) (12), in which the respective phosphorus centers were coordinated to the pentacarbonylmetal fragments. X-ray analysis was performed for the three diphospha[2]ferrocenophanes, 10a, 11, and 12, demonstrating that their P-P bond lengths are 2.3093(7), 2.261(5), and 2.2502(8) angstrom, respectively. Because these tether P-P lengths are smaller than an ideal distance between the two parallel C5H5 rings of ferrocene, the two C5H4 rings of each of 10a, 11, and 12 are inclined from the parallel by 12.9 degrees, 9.7 degrees, and 13.6 degrees, respectively. DFT calculations were performed on (PH)(2)-bridged [2]ferrocenophane as a model-compound, and showed that there are two conformational isomers. One, named the parallel form, features a P-P bond that is almost parallel to the axis passing through the centers of the two C5H4 rings, while the P-P bond of the other, named the twist form, leans with the two C5H4 rings twisted. The smaller inclined angle of 9.7 degrees observed for 11 was found to result from its parallel-form conformation, while the C5H4 rings of 10a and 12 were more inclined due to adoption of the twist-form conformation. (C) 2012 Elsevier B.V. All rights reserved.