%0 Journal Article %1 Kaim.1986d %A Kaim, Wolfgang %A Kohlmann, Stephan. %D 1986 %J Inorganic Chemistry %K ESR ESR;ENDOR ESR;tetrazine VIB azobipyridine azopyridine binuclear carbonyl complex complex;ESR complex;pyridyltetrazine molybdenum %N 19 %P 3442--3448 %R 10.1021/ic00239a025 %T Semireduced bridging ligands containing N-N multiple bond coordination sites. ESR study of binuclear Group 6 metal carbonyl complexes %V 25 %X Centrosym. binuclear metal carbonyl complexes of anion radical ligands contg. the azo group -N:N- were studied by using ESR. The ligands employed were 1,2,4,5-tetrazine (tz), 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), and azo-2,2'-bipyridine (abpy). The radical complexes studied were: (m-(N1,N4)-tz.-)[M(CO)5]2 (M = Mo, W); (m-bptz.-)[M(CO)4]2, and (m-abpy).-)[M(CO)4]2 (M = Cr, Mo, W). The ESR spectra of abpy species are line rich and insufficiently resolved so that ENDOR spectroscopy was used for (m-abpy.-)[Mo(CO)4]2. In contrast, the tetrazine complexes exhibit a rather simple ESR hyperfine structure because of spin localization at the 4 N centers in the tetrazine ring. The obsd. response of the hyperfine structure on metal coordination is well reproduced by HMO-McLachlan perturbation calcns. of the spin distribution. Double coordination of equiv. metal fragments and spin localization at the tetrazine N centers create exceptionally favorable conditions to detect metal isotope coupling; a survey of these and several related anion radical complexes shows that the small metal isotope splittings are caused by s/p spin polarization originating from the coordinating N p center. [on SciFinder(R)]

@article{Kaim.1986d, abstract = {Centrosym. binuclear metal carbonyl complexes of anion radical ligands contg. the azo group -N:N- were studied by using ESR. The ligands employed were 1,2,4,5-tetrazine (tz), 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), and azo-2,2'-bipyridine (abpy). The radical complexes studied were: (\textgreek{m}-(N1,N4)-tz.-)[M(CO)5]2 (M = Mo, W); (\textgreek{m}-bptz.-)[M(CO)4]2, and (\textgreek{m}-abpy).-)[M(CO)4]2 (M = Cr, Mo, W). The ESR spectra of abpy species are line rich and insufficiently resolved so that ENDOR spectroscopy was used for (\textgreek{m}-abpy.-)[Mo(CO)4]2. In contrast, the tetrazine complexes exhibit a rather simple ESR hyperfine structure because of spin localization at the 4 N centers in the tetrazine ring. The obsd. response of the hyperfine structure on metal coordination is well reproduced by HMO-McLachlan perturbation calcns. of the spin distribution. Double coordination of equiv. metal fragments and spin localization at the tetrazine N centers create exceptionally favorable conditions to detect metal isotope coupling; a survey of these and several related anion radical complexes shows that the small metal isotope splittings are caused by \textgreek{s}/\textgreek{p} spin polarization originating from the coordinating N \textgreek{p} center. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Kaim, Wolfgang and Kohlmann, Stephan.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/26ad1a8ae43588b97eaaf9c190e5536b6/huebleriac}, doi = {10.1021/ic00239a025}, interhash = {8f4f2bb44536807f1df27fd633b9cf33}, intrahash = {6ad1a8ae43588b97eaaf9c190e5536b6}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {ESR ESR;ENDOR ESR;tetrazine VIB azobipyridine azopyridine binuclear carbonyl complex complex;ESR complex;pyridyltetrazine molybdenum}, number = 19, pages = {3442--3448}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Semireduced bridging ligands containing N-N multiple bond coordination sites. ESR study of binuclear Group 6 metal carbonyl complexes}, volume = 25, year = 1986 }