Tungsten(VI) Complex of N‐Fused Porphyrin Absorbing Near‐Infrared Light beyond 1000 nm. Issue 6 (14th February 2020) - Yamamoto, Takaaki
Abstract: Incorporating tungsten into the N3 core of a N‐fused porphyrin (NFP; 1 ) affords high‐valent tungsten(VI)‐NFP complexes, WClO2 ‐1 and 21‐chlorinated WClO2 ‐3 . The X‐ray structure of WClO2 ‐1 reveals a distorted octahedral geometry with sitting atop metal coordination. The absorption spectrum of WClO2 ‐1 displays bathochromically shifted Q‐like bands beyond 1000 nm, indicating an inherently narrow HOMO‐LUMO energy gap. DFT calculations show that the degeneracy of the LUMO and LUMO+1 pair of 1 is significantly resolved by the tungsten(VI) coordination. Conclusively, magnetic circular dichroism (MCD) spectroscopy and cyclic voltammetry provide a rationale for the narrow HOMO‐LUMO energy gap in the "16‐electron" d 0 tungsten(VI)‐NFP complexes. Abstract : Far and NIR : "16‐Electron" d 0 tungsten(VI) complexes of an N‐fused porphyrin show characteristic absorption in the NIR region beyond 1000 nm. The coordination of a high‐valent tungsten ion lowers the LUMO energy of the fused porphyrin, leading to a narrower HOMO‐LUMO energy gap.