Intensity enhancement of intraligand singlet-triplet pi-pi* transition for the coordinated beta-diketonate in Ni(II) complexes with a nitroxide radical

摘要

Room temperature and low temperature magnetic circular dichroism (MCD) in the intraligand spin-forbidden ringlet-triplet n-n` transition for the coordinated beta-diketonate ligands were observed for the beta-diketonato Ni(II) complexes with a chelated imino or nitronyl nitroxide radical, but not for the beta-diketonato Ni(II) complexes without the radical ligands. This is elucidated by the borrowing mechanism from the singlet-singlet pi-pi* transition through the hypothetical interligand beta-diketonate-to-radical charge transfer (LLCT) in contrast to the case of Cr(III) complexes. (c) 2006 Elsevier B.V. All rights reserved.