Non-chelating polydentate N-heterocyclic carbenes through assembly approaches

作者：Lin Ya Fan; Liu Chih Hsun; Hu Chung Hao; Chiu Ching Wen^*

来源：Phosphorus, Sulfur, and Silicon and the Related Elements, 2016, 191(4): 613-617.

DOI：10.1080/10426507.2015.1128918

• N-Heterocyclic carbine
• multi-dentate ligands
• non-chelating

Bridging-type polydentate N-heterocyclic carbene (NHC) ligands are valuable building blocks for organometallic supramolecules. In order to quickly expand the ligand library of poly-NHC, we have assembled several bi-functional carbene precursors with spiroborate, phthalimide and metal-carboxylate to yield poly-NHC ligands with various denticities and geometries. Condensation of 4,5-dihyxdroxy-N,N-diaryl-benzimidazolium and arylboronic acids leads to a spiroborate-linked bis-benzimidazolium salt, which can be further deprotonated to give a linear anionic bis-NHC. The second approach utilizes the dehydrative condensation of phthalic anhydride functionalized benzimidazole with poly-anilines to afford a series of poly-benzimidazole compounds, which can be converted into the corresponding poly-nuclear metal-NHC complexes after alkylation and metalation. The introduction of a benzoate group to bi-functional carbene precursor facilitates the assembly of poly-benzimidazolium salts with metal salts leading to MCl2 (M=Zn, Co)-linked C-2h symmetric bis-benzimidazoliums and a penta-Zn cluster-linked tetra-benzimidazolium.

• 出版日期2016-4-2