%0 Journal Article %1 Kaim.1992b %A Kaim, Wolfgang %A Roth, Thomas %A Olbrich-Deussner, Barbara %A Gross-Lannert, Renate %A Jordanov, Jeanne %A Roth, Eberhard K. H. %D 1992 %J Journal of the American Chemical Society %K carbonyl chromium complex complex;susceptibility metal paramagnetic susceptibility;manganese susceptibility;paramagnetism transition %N 14 %P 5693--5697 %R 10.1021/ja00040a031 %T Unexpected paramagnetism of mono- and polynuclear 18 valence electron metal carbonyl complexes [(CnRn)(CO)2M]k(L), M = chromium, manganese; k = 1, 2, 4. Implications for photoreactivity %V 114 %X Several mono- and polynuclear complexes of the organometallic 16 valence electron fragments (CuRn)(CO)2M, M = Cr (n = 6) and Mn (n = 5), with conventional two-electron nitrogen-donor ligands L (acceptor-substituted pyridines, h1,2-pyrazine) or with h1,4-tetracyanoethylene (TCNE) show sizable metal-based paramagnetism in the solid state at room temp. In contrast to paramagnetic (C6H6)(CO)2Cr(py), the corresponding complex (C5H5)(CO)2Mn(py) of unsubstituted pyridine and the dinuclear complex [(C5H4Me)(CO)2Mn]2(m-1,4-Me2P-C6H4-PMe2) of a basic, p-accepting diphosphine exhibit essentially diamagnetic behavior. Magnetic susceptibilities at 300 K can be correlated with ligand \dqstrengths\dq as represented by basicities of L. The susceptibilities of the paramagnetic species were found to decrease considerably at lower temps., indicating a diamagnetic ground state for all compds. The easy accessibility of low-lying magnetic states of integer spin is attributable to the low symmetry of the complexes, to the intrinsically small ligand field splitting of low-valent chromium and manganese, and to the presence of one weak ligand, L. Anal. of the tetranuclear complex [(C5Me5)(CO)2Mn]4(h4-TCNE) reveals magnetic coupling between the four metal centers but no direct involvement of TCNE as a radical. The measured susceptibilities correlate with the photolability of the compds. and with the small g factors of singly reduced complexes, all effects being caused by the low-lying dz2 orbital. [on SciFinder(R)]

@article{Kaim.1992b, abstract = {Several mono- and polynuclear complexes of the organometallic 16 valence electron fragments (CuRn)(CO)2M, M = Cr (n = 6) and Mn (n = 5), with conventional two-electron nitrogen-donor ligands L (acceptor-substituted pyridines, \textgreek{h}1,2-pyrazine) or with \textgreek{h}1,4-tetracyanoethylene (TCNE) show sizable metal-based paramagnetism in the solid state at room temp. In contrast to paramagnetic (C6H6)(CO)2Cr(py), the corresponding complex (C5H5)(CO)2Mn(py) of unsubstituted pyridine and the dinuclear complex [(C5H4Me)(CO)2Mn]2(\textgreek{m}-1,4-Me2P-C6H4-PMe2) of a basic, \textgreek{p}-accepting diphosphine exhibit essentially diamagnetic behavior. Magnetic susceptibilities at 300 K can be correlated with ligand {\dq}strengths{\dq} as represented by basicities of L. The susceptibilities of the paramagnetic species were found to decrease considerably at lower temps., indicating a diamagnetic ground state for all compds. The easy accessibility of low-lying magnetic states of integer spin is attributable to the low symmetry of the complexes, to the intrinsically small ligand field splitting of low-valent chromium and manganese, and to the presence of one weak ligand, L. Anal. of the tetranuclear complex [(C5Me5)(CO)2Mn]4(\textgreek{h}4-TCNE) reveals magnetic coupling between the four metal centers but no direct involvement of TCNE as a radical. The measured susceptibilities correlate with the photolability of the compds. and with the small g factors of singly reduced complexes, all effects being caused by the low-lying dz2 orbital. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Kaim, Wolfgang and Roth, Thomas and Olbrich-Deussner, Barbara and Gross-Lannert, Renate and Jordanov, Jeanne and Roth, Eberhard K. H.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2f8032224308e8fa182291725ba8df096/huebleriac}, doi = {10.1021/ja00040a031}, interhash = {e93e912fa2766c9816d9ff913633ed19}, intrahash = {f8032224308e8fa182291725ba8df096}, issn = {0002-7863}, journal = {Journal of the American Chemical Society}, keywords = {carbonyl chromium complex complex;susceptibility metal paramagnetic susceptibility;manganese susceptibility;paramagnetism transition}, number = 14, pages = {5693--5697}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Unexpected paramagnetism of mono- and polynuclear 18 valence electron metal carbonyl complexes [(CnRn)(CO)2M]k(L), M = chromium, manganese; k = 1, 2, 4. Implications for photoreactivity}, volume = 114, year = 1992 }