%0 Journal Article %1 Sieger.2004 %A Sieger, Monika %A Kaim, Wolfgang %A Stufkens, Derk J. %A Snoeck, Theo L. %A Stoll, Hermann %A Zalis, Stanislav. %D 2004 %J Dalton Transactions %K DFT Raman catalysis cobalt complex;EPR cyclopentadienyl diimine excited hydride intermediate iridium;reduced resonance rhodium spectra state transfer %N 22 %P 3815--3821 %R 10.1039/B411892H %T Reduced and excited states of the intermediates (a-diimine)(C5R5)Rh in hydride transfer catalysis schemes: EPR and resonance Raman spectroscopy, and comparative DFT calculations of Co, Rh and Ir analogues %X The electronic structures of the highly air-sensitive intermediates (N-N)(C5Me5)Rh, (N-N = 2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpym), 2,2'-bipyrazine (bpz) and 3,3'-bipyridazine (bpdz)) of hydride transfer catalysis schemes were studied through resonance Raman (rR) spectroscopy and through EPR of the reduced forms (N-N)(C5Me5)Rh.bul.-. The rR results are compatible with a predominant MLCT character of the lowest excited states (N-N)(C5Me5)Rh*, and the EPR spectra of the reduced states reveal the presence of anion radical ligands, (N-N).bul.-, coordinated by unusually electron rich rhodium(I) centers. The exptl. results, including the assignments of electronic transitions, are supported by DFT calcns. for the model compds. (N-N)(C5H5)Rho/.bul.-, N-N = bpy or bpym. The calcns. confirm a significant but not complete mixing of metal and ligand orbitals in the LUMO which still retains about 3/4 p*(N-N) character. DFT calcns. on (bpy)(C5H5)M and (bpy)(C5H5)ClM+, M = Co, Rh, Ir, agree with the exptl. results such as the differences between the homologues, esp. the different LUMO characters of the precursor cations in the case of Co ($\rightarrow$dM) and Rh or Ir ($\rightarrow$p*(bpy)). on SciFinder(R)

@article{Sieger.2004, abstract = {The electronic structures of the highly air-sensitive intermediates (N-N)(C5Me5)Rh, (N-N = 2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpym), 2,2'-bipyrazine (bpz) and 3,3'-bipyridazine (bpdz)) of hydride transfer catalysis schemes were studied through resonance Raman (rR) spectroscopy and through EPR of the reduced forms [(N-N)(C5Me5)Rh].bul.-. The rR results are compatible with a predominant MLCT character of the lowest excited states [(N-N)(C5Me5)Rh]*, and the EPR spectra of the reduced states reveal the presence of anion radical ligands, (N-N).bul.-, coordinated by unusually electron rich rhodium(I) centers. The exptl. results, including the assignments of electronic transitions, are supported by DFT calcns. for the model compds. [(N-N)(C5H5)Rh]o/.bul.-, N-N = bpy or bpym. The calcns. confirm a significant but not complete mixing of metal and ligand orbitals in the LUMO which still retains about 3/4 \textgreek{p}*(N-N) character. DFT calcns. on (bpy)(C5H5)M and [(bpy)(C5H5)ClM]+, M = Co, Rh, Ir, agree with the exptl. results such as the differences between the homologues, esp. the different LUMO characters of the precursor cations in the case of Co ($\rightarrow$dM) and Rh or Ir ($\rightarrow$\textgreek{p}*(bpy)). [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Sieger, Monika and Kaim, Wolfgang and Stufkens, Derk J. and Snoeck, Theo L. and Stoll, Hermann and Zalis, Stanislav.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2495b62852b43f3c10fe39672eabbbb1a/huebleriac}, doi = {10.1039/B411892H}, interhash = {6f51281eab0ac1f7618262037b772809}, intrahash = {495b62852b43f3c10fe39672eabbbb1a}, issn = {1477-9226}, journal = {Dalton Transactions}, keywords = {DFT Raman catalysis cobalt complex;EPR cyclopentadienyl diimine excited hydride intermediate iridium;reduced resonance rhodium spectra state transfer}, number = 22, pages = {3815--3821}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Reduced and excited states of the intermediates (\textgreek{a}-diimine)(C5R5)Rh in hydride transfer catalysis schemes: EPR and resonance Raman spectroscopy, and comparative DFT calculations of Co, Rh and Ir analogues}, year = 2004 }