The reactivities of novel rhodium CCC-type pincer complexes CCC型钳形铑配合物的反应性

Lin，Jianfeng1,2; Luo，Ming1; Xia，Haiping1,2

2021-09-01

10.1360/TB-2021-0040

Chinese Science Bulletin-Chinese   影响因子和分区

0023-074X

2095-9419

Pincer complexes have attracted chemists' attention because of their unique structures, properties, and catalytic applications. Among these pincer complexes, most of them are based on heteroatoms, such as nitrogen, oxygen, phosphorus, sulfur and so on. Few examples that three carbon atoms coordinate to metal (CCC-type pincer) have been reported due to their highly active reactivities. Recently, our group reported a series of novel metal bridgehead fused-ring organometallics, named carbolong complexes. Carbolong complexes are special pincer complexes which are metal bridgehead polycyclic frameworks featuring a conjugate carbon chain (at least 7 carbons and we call these carbon chains carbolong ligand) coordinated to a metal atom via at least three metal-carbon σ bonds and note that the d orbital of metal atom in cooperation with π conjugation is a particular characteristic in carbolong complexes. In cooperation with metal, carbolong complexes exhibit numerous distinctive properties different form typical aromatics, such as mixed aromaticity, broad absorption from the UV to the visible and near-infrared region, and excellent photothermal effects, indicating their potential applications in materials science and biomedicine. The reported carbolong complexes were mostly based on osmium, limited their application development. Thanks to the efficient method we developed very recently, the rhodium carbolong complexes, rhodapentalenes were synthesized successfully, which displayed unique intrinsic aromaticity and diverse reactivities. As a novel CCC-type rhodium pincer complexes, the reactivities of rhodapentalenes were rarely investigated. In this report, we investigated the reactivities of two novel rhodium CCC-type pincer complexes. The results showed rhodium carbolong complex 1 could be oxidized by activated MnO and led to complexes 3 and 4, which were confirmed by NMR spectra and single crystal X-ray analysis. Complex 3 was an oxidation product and originated from the oxidation of hydroxy in CCC-type pincer ligand of complex 1. However, complex 4 formed through an acid promoted ring-opening reaction. Meanwhile, acid promoted ring-opening reaction could also occur in complex 3, leading to complex 5. Whereas the cis-1,3-diene moiety in complex 5 was unstable in thermodynamics, thus it would isomerize to trans-1,3-diene and transformed to complex 6, which was obtained from the crystallization process. Due to the special structure of complex 5, the isomerization could occur easily by proton migration rather than configuration inversion of sp carbon. In addition, rhodapentalene 2 could react with azidotrimethylsilane, leading to CCN-type pincer complex 7 at ambient conditions. In this reaction, he ring expansion reaction of rhodapentalene occurred by a nitrogen insertion, as a result, the insertion of nitrogen to rhodium carbene by azidotrimethylsilane and the transformation of a CCC-pincer complex to a CCN-pincer complex is realized for the first time. Besides, rhodapentalene 2 could react with diphenylphosphine and resulted in CCP-type pincer complex 8. Similar ring expansion reaction of rhodapentalene took place by inserting a diphenylphosphine group. In particular, the sp carbon coordinated to rhodium in the other five-membered ring was protonated to sp carbon. Further, deuterium labeling reactions were preformed and revealed that the proton originated from diphenylphosphine. Thus, we proposed a proton migration mechanism through a metal-hydride intermediate in this reaction. The reaction realized the insertion of phosphine to rhodium carbene by diphenylphosphine and the transformation of a CCC-pincer complex to a CCP-pincer complex for the first time. The dearomatization reactions of rhodapentalene were realized by this facile method. In summary, these results revealed the diverse and unique reactivities of CCC-type rhodium pincer complexes and offered a convenient method to modify offered CCC-type rhodium pincer complexes. It also laid a good foundation for developing new rhodium pincer catalyzed reactions.

Carbolong chemistry CCC-type pincer complex Rhodium complexes Ring-expanding reaction Ring-opening reaction

EI

中文

第一 ; 通讯

20213910941993

Aromatization ; Atoms ; Carbon ; Energy dispersive X ray analysis ; Infrared devices ; Manganese oxide ; Metals ; Nuclear magnetic resonance spectroscopy ; Organometallics ; Oxidation ; Rhodium compounds ; Single crystals ; Synthesis (chemical) ; Thermodynamics ; X ray diffraction analysis

Thermodynamics:641.1 ; Chemistry:801 ; Physical Chemistry:801.4 ; Chemical Reactions:802.2 ; Chemical Products Generally:804 ; Organic Compounds:804.1 ; Atomic and Molecular Physics:931.3 ; Crystalline Solids:933.1 ; Radiation Measurements:944.8

2-s2.0-85115444692

Scopus

1.Shenzhen Grubbs Institute,Guangdong Provincial Key Laboratory of Catalysis,Department of Chemistry,Southern University of Science and Technology,Shenzhen,518055,China
2.Department of Chemistry,Xiamen University,Xiamen,361005,China

Lin，Jianfeng,Luo，Ming,Xia，Haiping. The reactivities of novel rhodium CCC-type pincer complexes CCC型钳形铑配合物的反应性[J]. Chinese Science Bulletin-Chinese,2021,66(25):3333-3341.

Lin，Jianfeng,Luo，Ming,&Xia，Haiping.(2021).The reactivities of novel rhodium CCC-type pincer complexes CCC型钳形铑配合物的反应性.Chinese Science Bulletin-Chinese,66(25),3333-3341.

Lin，Jianfeng,et al."The reactivities of novel rhodium CCC-type pincer complexes CCC型钳形铑配合物的反应性".Chinese Science Bulletin-Chinese 66.25(2021):3333-3341.