%0 Journal Article %1 Zalis.2003 %A Zalis, Stanislav %A Sieger, Monika %A Greulich, Stefan %A Stoll, Hermann %A Kaim, Wolfgang. %D 2003 %J Inorganic Chemistry %K DFT HOMO LUMO bathochromic bipyridine cationic charge chloro complex complex;DFT cyclopentadienyl diazabutadiene hypsochromic interaction iridium shift;orbital transfer %N 17 %P 5185--5191 %R 10.1021/ic034464k %T Replacement of 2,2'-Bipyridine by 1,4-Diazabutadiene Acceptor Ligands: Why the Bathochromic Shift for (NN̂)IrCl(C5Me5)+ Complexes but the Hypsochromic Shift for (NN̂)Ir(C5Me5)? %V 42 %X Replacement of 2,2'-bipyridine (bpy) by substituted 1,4-diazabutadiene (R-DAB) a-diimine ligands NN̂ leads to a substantial hypsochromic shift of $\sim$0.8 eV for the long-wavelength absorption band in (NN̂)Ir(C5Me5) but to a bathochromic absorption shift of $\sim$0.4 eV for (NN̂)IrCl(C5Me5)+. DFT calcns. on model complexes based on exptl. (R-DAB compds.) and geometry-optimized structures (bpy systems) reveal that the low-energy transitions of the cationic chloro complexes are largely of ligand-to-ligand charge-transfer character L'LCT (L = a-diimine, L' = Cl) whereas the neutral compds. exhibit p $\rightarrow$ p* transitions between the considerably mixed metal dp and a-diimine p* orbitals. The much more pronounced metal-ligand orbital interaction for the R-DAB complexes causes the qual. different shifts on replacing the stronger basic bpy by the better p-acceptors R-DAB. Only the LUMO of the neutral compds. is destabilized on replacement of bpy by R-DAB whereas the LUMO of (NN̂)IrCl(C5R'5)+ and both HOMOs are stabilized through this change. on SciFinder(R)

@article{Zalis.2003, abstract = {Replacement of 2,2'-bipyridine (bpy) by substituted 1,4-diazabutadiene (R-DAB) \textgreek{a}-diimine ligands NN̂ leads to a substantial hypsochromic shift of $\sim$0.8 eV for the long-wavelength absorption band in (NN̂)Ir(C5Me5) but to a bathochromic absorption shift of $\sim$0.4 eV for [(NN̂)IrCl(C5Me5)]+. DFT calcns. on model complexes based on exptl. (R-DAB compds.) and geometry-optimized structures (bpy systems) reveal that the low-energy transitions of the cationic chloro complexes are largely of ligand-to-ligand charge-transfer character L'LCT (L = \textgreek{a}-diimine, L' = Cl) whereas the neutral compds. exhibit \textgreek{p} $\rightarrow$ \textgreek{p}* transitions between the considerably mixed metal d\textgreek{p} and \textgreek{a}-diimine \textgreek{p}* orbitals. The much more pronounced metal-ligand orbital interaction for the R-DAB complexes causes the qual. different shifts on replacing the stronger basic bpy by the better \textgreek{p}-acceptors R-DAB. Only the LUMO of the neutral compds. is destabilized on replacement of bpy by R-DAB whereas the LUMO of [(NN̂)IrCl(C5R'5)]+ and both HOMOs are stabilized through this change. [on SciFinder(R)]}, added-at = {2019-07-15T13:41:23.000+0200}, author = {Zalis, Stanislav and Sieger, Monika and Greulich, Stefan and Stoll, Hermann and Kaim, Wolfgang.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/25ef1839f0429637d0dada95c2a501180/b_schwederski}, doi = {10.1021/ic034464k}, interhash = {96bc57f69f317aeaebbcec6deeaf001e}, intrahash = {5ef1839f0429637d0dada95c2a501180}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {DFT HOMO LUMO bathochromic bipyridine cationic charge chloro complex complex;DFT cyclopentadienyl diazabutadiene hypsochromic interaction iridium shift;orbital transfer}, number = 17, pages = {5185--5191}, timestamp = {2019-07-15T11:42:10.000+0200}, title = {Replacement of 2,2'-Bipyridine by 1,4-Diazabutadiene Acceptor Ligands: Why the Bathochromic Shift for [(NN̂)IrCl(C5Me5)]+ Complexes but the Hypsochromic Shift for (NN̂)Ir(C5Me5)?}, volume = 42, year = 2003 }