Influence of the d-electron count on CO binding by three-coordinate [(tBu2PCH2SiMe2)2N]Fe, -Co, and -Ni
Influence of the d-electron count on CO binding by three-coordinate [(tBu2PCH2SiMe2)2N]Fe, -Co, and -Ni
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DOI：
10.1021/ic7023764
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发表时间：
2008-01-21
影响因子：
4.6
通讯作者：
Caulton, Kenneth G.
中科院分区：
文献类型：
--
作者：
Ingleson, Michael J.;Fullmer, Benjamin C.;Caulton, Kenneth G.
用Mg还原（PNP）MCI [PNP = ((Bu2PCH2SiMe2)-Bu-t)(2)N]得到M = Fe（S = 3/2）和Ni的三坐标t形（PNP）M。测试了它们对CO的反应性；Ni与一个CO结合，但只能可逆地结合（即CO在真空中完全丢失），并且具有CO拉伸频率，显示Nil的有效回给。（PNP）Ni（CO）的结构介于平面和四面体之间，与平面d(8)类似物（PNP） CO （CO）相反，羰基化的这种结构重组改变了单占据分子轨道从具有可忽略的磷特征[在（PNP）Ni的电子顺磁共振（EPR）谱中没有P超精细结构]到具有足够的P特征在CO的EPR谱中具有三重态结构。（PNP）Fe（CO）中少一个电子的存在（与CO类似物相比）导致两个CO结合，并且（PNP）Fe(CO)2被表征为具有方锥体结构的自旋双重态。密度泛函理论计算加强了对d(n)系列（n = 7-9）结构和光谱变化的理解。
Reduction of (PNP)MCI [PNP = ((Bu2PCH2SiMe2)-Bu-t)(2)N] with Mg gives three-coordinate, T-shaped (PNP)M for M = Fe(S = 3/2) and Ni. Their reactivity was tested toward CO; Ni binds one CO, but only reversibly (i.e., CO is completely lost in vacuum), and has a CO stretching frequency showing effective back-donation by Nil. The structure of (PNP)Ni(CO) is intermediate between planar and tetrahedral, in contrast to the planar d(8) analogue, (PNP)Co(CO), This structural reorganization on carbonylation changes the singly occupied molecular orbital from having negligible phosphorus character [no P hyperfine structure in the electron paramagnetic resonance (EPR) spectrum of (PNP)Ni] to having enough P character to have a triplet structure in the EPR spectrum of the CO. The presence of one fewer electron in (PNP)Fe (vs the Co analogue) leads to binding of two CO, and (PNP)Fe(CO)2 is characterized as a spin doublet with square-pyramidal structure. Density functional theory calculations strengthen the understanding of the structural and spectroscopic changes along this d(n) series (n = 7-9).