Synthesis and Crystal Structures of P-Iron-Substituted Phosphinoborane Monomers
Synthesis and Crystal Structures of P-Iron-Substituted Phosphinoborane Monomers
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P-铁取代的膦硼烷单体的合成和晶体结构
DOI：
10.1021/om201287s
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发表时间：
2012
期刊：
影响因子：
2.8
通讯作者：
Kazuyuki Kubo
中科院分区：
文献类型：
--
作者：
T. Ozawa;T. Wada;T. Inomata;Y. Funahashi;H. Masuda;中野 元裕;Kazuyuki Kubo
由Cp（CO）2FeCl和（Li）（Ar）PBMes 2反应，合成了一族P-铁取代膦硼烷Cp（CO）2Fe{P（Ar）BMes 2}（Ar = Ph，Mes，Tipp，Mes*）.所有配合物均通过~ 1H、~（11）B和~（31）P NMR、IR和X射线晶体学进行了表征。在红外光谱中，所有的配合物显示出相似的羰基伸缩频率，显着高于那些密切相关的磷化物配合物。这些观察结果表明，铁上的填充d轨道和磷上的孤对电子之间的排斥相互作用在所研究的铁膦硼烷中不太严重，这很可能是因为它们中发生的P→B π相互作用。膦硼烷磷的31 P {1H} NMR化学位移随着Ar基团空间体积的增加而向高场移动，顺序为Ph（−51.4 ppm）< Mes（−68.8 ppm）< Tipp（−84.9 ppm）。然而，具有空间要求最高的Mes* 基团的磷出现在-44.9 ppm的出乎意料的低场值，这可能反映了它的结构特性。每个配合物的1H NMR谱显示两组信号，归属于硼原子上的不等价的Mes基团，作为围绕P-B键的受阻旋转的结果。这种高的转动势垒很可能是由于P-B键中的重要双键特征。X-射线衍射研究证实了本文所考虑的铁-膦基硼烷是单体物质。每个分子由具有短P-B键的几乎平面的膦基硼烷片段组成。随着Ar基团变大，Fe-P键显著伸长，表明其相对于空间拥挤的有些脆弱的性质。相比之下，在整个系列的铁-膦硼烷的P-B键距的变化是相对较小的，这表明P B双键的字符是平衡的磷周围的取代基的空间和电子效应。
A family ofP-iron-substituted phosphinoboranes, Cp(CO)2Fe{P(Ar)BMes2} (Ar = Ph, Mes, Tipp, Mes*), have been prepared from the reaction of Cp(CO)2FeCl and (Li)(Ar)PBMes2. All the complexes have been characterized successfully by1H,11B, and31P NMR; IR spectroscopy; and X-ray crystallography. In the IR spectra, all the complexes display similar carbonyl stretching frequencies that are remarkably higher than those of closely related phosphide complexes. These observations indicate that a repulsive interaction between the filled d orbital on the iron and the lone pair on the phosphorus is less severe in the studied iron-phosphinoboranes, which is most likely because of the P→B π interaction that occurs in them. The31P{1H} NMR chemical shifts of the phosphinoborane phosphorus move upfield with the increasing steric bulk of the Ar groups in the order Ph (−51.4 ppm) < Mes (−68.8 ppm) < Tipp (−84.9 ppm). However, the phosphorus bearing the most sterically demanding Mes* group appears at an unexpectedly downfield value of −44.9 ppm, which is probably reflective of its structural peculiarities. The1H NMR spectrum of each complex displays two sets of signals, assignable to inequivalent Mes groups on the boron atom, as a consequence of a hindered rotation around the P–B bond. This high rotational barrier most likely results from the significant double-bond character in the P–B bond. The X-ray diffraction studies have confirmed the iron-phosphinoboranes considered herein to be monomeric species. Each molecule consists of a nearly planar phosphinoborane fragment with a short P–B bond. The Fe–P bond is notably elongated as the Ar group becomes larger, demonstrating its somewhat vulnerable nature with respect to steric congestion. In contrast, the variation in the P–B bond distance is relatively small throughout the series of iron-phosphinoboranes, suggesting that the PB double-bond character is balanced by steric and electronic effects of the substituents around the phosphorus.