Poly-membered macrometallacyclic complexes of silver and gold with functionalized N-Heterocyclic carbene and functionalized 2-borabicyclo[1.1.0]but-1(3)-ene ligands: A DFT study

The structures, stability, chemical bonding, electronic spectra and aromaticity of eight-, ten- and twelve-membered macrometallacyclic complexes of silver and gold bonded to functionalized N-Heterocyclic carbene (NHC) ligands and functionalized 2-borabicyclo[1.1.0]but-1(3)-ene (2BT) ligands have been investigated using density functional theory (DFT). Calculated results indicated that the lowest-energy structures of the poly-membered macrometallacyclic complexes of silver and gold coordinated with the functionalized 2BT ligands indicated that these complexes contain planar tetracoordinate carbons (ptCs), thus a kind of novel method to construct poly-membered macrometallacyclic complexes containing ptC was obtained. The electronic absorption spectra of the eight-membered macrometallacyclic complexes of silver and gold with the functionalized 2BT ligands have a blue shift compared to that of with the functionalized NHC ligands. In contrast, the electronic absorption spectra of the ten- and twelve-membered macrometallacyclic complexes coordinated with the functionalized 2BT ligands have a significant red shift compared to that of with the functionalized NHC ligands. The electron emission maximum wavelengths of the macrometallacyclic complexes of silver and gold bonded to the functionalized NHC ligands and the functionalized 2BT ligands are in the range of 414–612 nm and 468–854 nm, respectively. The centers of the three- and five-membered rings of the poly-membered macrometallacyclic complexes have strong acromaticity.