Characterization of Rh?Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe3)2 (L = AlMe2, Al(NMe2)2, BR2, SiR3, CH3, Cl, or OCH3): Theoretical Insight
Characterization of Rh?Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe3)2 (L = AlMe2, Al(NMe2)2, BR2, SiR3, CH3, Cl, or OCH3): Theoretical Insight
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Rh(PAlP) 中 Rh?Al 键的表征（PAlP = 钳型二膦基铝基配体）与 Rh(L)(PMe3)2 (L = AlMe2, Al(NMe2)2, BR2, SiR3, CH3,
DOI：
10.1021/acs.inorgchem.8b03493
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发表时间：
2019
影响因子：
4.6
通讯作者：
Sakaki Shigeyoshi
中科院分区：
文献类型：
--
作者：
Kuriakose Nishamol;Zheng Jia-Jia;Saito Teruhiko;Hara Naofumi;Nakao Yoshiaki;Sakaki Shigeyoshi
用密度泛函方法研究了Rh（PAlP）1{PAlP =钳形二膦铝配体Al[NCH 2（PiPr 2）]2（C6 H 4）2NMe}中唯一的Rh-Al键.配合物1在Rh原子上有四个双占据的非键d轨道，其中一个Rh d轨道主要参与Rh-Al键，Rh和Al原子之间具有相当大的键重叠，类似于共价键。有趣的是，Rhδ−−Alδ+极化在1的键合MO中观察到，这与在通常的配位键中发现的Rhδ+−Eδ−（E =配位原子）极化相反。这种不寻常的极化产生的Al价轨道的存在下，在显着更高的能量比Rh价轨道能量。通过与类似的Rh配合物RhL（PMe 3）2（L = AlMe 2为2，L = Al（NMe 2）2为3，L = BMe 2为4，L = SiMe 3为5，L = SiH 3为6，L = CH 3为7，L = OMe为8，L = Cl为9）的比较，进一步揭示了1的特征.正如预期的那样，7、8和9在Rh-E键MO中表现出常见的Rhδ+−Eδ−极化（E =配位原子）。另一方面，在2 - 5的Rh-E键MO中观察到反向的Rhδ−−Eδ+极化，类似于在1中，而在6中Rh-Si键几乎没有极化。这些结果可以用配体的价轨道能来理解。由于1的LUMO主要由Rh的4dσ、5s和5 p轨道以及Al的3s和3 p轨道组成，因此Rh和Al原子都起着配位作用.例如，NH3和吡啶以相当大的结合能与Al和Rh原子配位。PAlP表现出显著强的反式影响，其与SiMe 3一样强，但比BMe 2弱。这些配体的反式效应主要取决于配体的价轨道能和配位E原子的共价键半径。
The unique Rh–Al bond in recently synthesized Rh(PAlP)1{PAlP = pincer-type diphosphino-aluminyl ligand Al[NCH2(PiPr2)]2(C6H4)2NMe} was investigated using the DFT method. Complex1has four doubly occupied nonbonding d orbitals on the Rh atom and one Rh d orbital largely participating in the Rh–Al bond which exhibits considerably large bonding overlap between Rh and Al atoms like in a covalent bond. Interestingly, Rhδ−−Alδ+polarization is observed in the bonding MO of1, which is reverse to Rhδ+−Eδ−(E = coordinating atom) polarization found in a usual coordinate bond. This unusual polarization arises from the presence of the Al valence orbital at significantly higher energy than the Rh valence orbital energy. Characteristic features of1are further unveiled by comparing1with similar Rh complexes RhL(PMe3)2(2for L = AlMe2,3for L = Al(NMe2)2,4for L = BMe2,5for L = SiMe3,6for L = SiH3,7for L = CH3,8for L = OMe, and9for L = Cl). As expected,7,8, and9exhibit usual Rhδ+−Eδ−polarization (E = coordinating atom) in the Rh–E bonding MO. On the other hand, the reverse Rhδ−−Eδ+polarization is observed in the Rh–E bonding MOs of2–5like in1, while the Rh–Si bond is polarized little in6. These results are clearly understood in terms of the valence orbital energy of the ligand. Because the LUMO of1mainly consists of the Rh 4dσ, 5s, and 5p orbitals and the Al 3s and 3p orbitals, both Rh and Al atoms play the role of coordinating site for a substrate bearing a lone pair orbital. For instance, NH3and pyridine coordinate to both Al and Rh atoms with considerably large binding energy. PAlP exhibits significantly strong trans influence, which is as strong as that of SiMe3but moderately weaker than that of BMe2. The trans influence of these ligands is mainly determined by the valence orbital energy of the ligand and the covalent bond radius of the coordinating E atom.