%0 Journal Article %1 Vlcek.1998 %A Vlcek, JR., Antonin %A Baumann, Frank %A Kaim, Wolfgang %A Grevels, Friedrich-Wilhelm %A Hartl, Frantisek. %D 1998 %J Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry %K ESR;chromium anion anion;IR anion;force bipyridine carbonyl chromium const distribution prepn;electron radical tetracarbonyl %N 2 %P 215--220 %T Electron distribution in the Cr(CO)4(bpy).bul.- (bpy = 2,2'-bipyridine) radical anion as revealed by EPR spectroscopy and IR spectroelectrochemistry of 13CO-enriched species %X Samples of Cr(CO)4(bpy) (bpy = 2,2'-bipyridine) with natural abundance of 13CO and with 16 and 79\% 13CO enrichment, resp., were reduced to the corresponding radical anion, Cr(CO)4(bpy).bul.- and studied by EPR and IR spectroscopies. ESR showed a considerable coupling of the unpaired electron with 13C(CO) of 0.601 mT which occurs to the 13CO ligands bound in axial positions, i.e. cis to bpy. It indicates an interaction between the singly occupied p* orbital of the bpy.bul.- ligand and the s and/or s* orbitals of the axial C-Cr-C bonds. Coupling to the 53Cr nucleus is rather small, 0.128 mT. IR spectra in the n(CO) region were used to calc. the CO stretching and interaction force consts. within the energy factored CO force field (EFFF) approxn. The stretching force consts. of the equatorial and axial CO ligands decrease by 68 and 21 N m-1, resp., on going from Cr(CO)4(bpy) to Cr(CO)4(bpy).bul.-. Thus, the redn. strengthens significantly the p-back donation to the equatorial (trans to bpy) CO ligands. on SciFinder(R)

@article{Vlcek.1998, abstract = {Samples of Cr(CO)4(bpy) (bpy = 2,2'-bipyridine) with natural abundance of 13CO and with 16 and 79{\%} 13CO enrichment, resp., were reduced to the corresponding radical anion, [Cr(CO)4(bpy)].bul.- and studied by EPR and IR spectroscopies. ESR showed a considerable coupling of the unpaired electron with 13C(CO) of 0.601 mT which occurs to the 13CO ligands bound in axial positions, i.e. cis to bpy. It indicates an interaction between the singly occupied \textgreek{p}* orbital of the bpy.bul.- ligand and the \textgreek{s} and/or \textgreek{s}* orbitals of the axial C-Cr-C bonds. Coupling to the 53Cr nucleus is rather small, 0.128 mT. IR spectra in the \textgreek{n}(CO) region were used to calc. the CO stretching and interaction force consts. within the energy factored CO force field (EFFF) approxn. The stretching force consts. of the equatorial and axial CO ligands decrease by 68 and 21 N m-1, resp., on going from Cr(CO)4(bpy) to [Cr(CO)4(bpy)].bul.-. Thus, the redn. strengthens significantly the \textgreek{p}-back donation to the equatorial (trans to bpy) CO ligands. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {{Vlcek, JR.}, Antonin and Baumann, Frank and Kaim, Wolfgang and Grevels, Friedrich-Wilhelm and Hartl, Frantisek.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/28884d4d36e11579ae56c5907a37e5b74/huebleriac}, interhash = {7c0fc8bfadf55597f49d36b289bd25c9}, intrahash = {8884d4d36e11579ae56c5907a37e5b74}, issn = {0300-9246}, journal = {Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry}, keywords = {ESR;chromium anion anion;IR anion;force bipyridine carbonyl chromium const distribution prepn;electron radical tetracarbonyl}, number = 2, pages = {215--220}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Electron distribution in the Cr(CO)4(bpy).bul.- (bpy = 2,2'-bipyridine) radical anion as revealed by EPR spectroscopy and IR spectroelectrochemistry of 13CO-enriched species}, year = 1998 }