%0 Journal Article %1 Hornung.2000 %A Hornung, Fridmann M. %A Heilmann, Oliver %A Kaim, Wolfgang %A Zalis, Stanislav %A Fiedler, Jan. %D 2000 %J Inorganic Chemistry %K alloxazine bipyridine bisimidazolylketone chloro chloro;ESR complex;ruthenium copper electrochem imidazolylketone metal oxo phosphine prepn redn;crystal redn;transition redn;tungsten reduced structure transition tungsten %N 18 %P 4052--4058 %R 10.1021/ic0001816 %T Metal vs. Ligand Reduction in Complexes of 1,3-Dimethylalloxazine (DMA) with Copper(I), Ruthenium(II), and Tungsten(VI). Crystal Structures of (DMA)WO2Cl2 and (Bis(1-methylimidazol-2-yl)ketone)WO2Cl2 %V 39 %X [(DMA)Cu(PPh3)2](BF4) (1, DMA = 1,3-dimethylalloxazine), [(DMA)Ru(bpy)2](PF6)2 (2), and (DMA)WO2Cl2 (3) were obtained as O4-N5-chelated species, as evident from an x-ray crystal structure anal. for 3 and from spectroscopy (NMR, IR, and UV-visible spectroelectrochem.) for 1 and 2. The tungsten(VI) center in 3 has its oxide ligands in a cis/equatorial position and the chloride ligands in a trans/axial position; it also exhibits a relatively short bond to O4 (2.232(3) \AA) and a very long bond to N5 (2.462(3) \AA). Comparison with the new structurally characterized compd. (BIK)WO2Cl2 (4) (BIK = bis(1-methylimidazol-2-yl)ketone), which has W-N bonds of $\sim$2.30 \AA, confirms the unusual length of the W-N bond in 3, probably caused by repulsion between one of the oxo ligands and the peri-hydrogen atom (H6) of DMA. One-electron redn. of the complexes occurs reversibly at room temp. in THF (1, 2) or at 198 K in CH2Cl2 (3). EPR spectroscopy reveals that this process is ligand-centered for 1 and 2 but metal-centered for 3. D. functional methods and ab initio methodol. were used to illustrate the correspondence in spin distribution between the radical anion p systems of alloxazine and isoalloxazine (flavosemiquinone). [on SciFinder(R)]

@article{Hornung.2000, abstract = {[(DMA)Cu(PPh3)2](BF4) (1, DMA = 1,3-dimethylalloxazine), [(DMA)Ru(bpy)2](PF6)2 (2), and (DMA)WO2Cl2 (3) were obtained as O4-N5-chelated species, as evident from an x-ray crystal structure anal. for 3 and from spectroscopy (NMR, IR, and UV-visible spectroelectrochem.) for 1 and 2. The tungsten(VI) center in 3 has its oxide ligands in a cis/equatorial position and the chloride ligands in a trans/axial position; it also exhibits a relatively short bond to O4 (2.232(3) {\AA}) and a very long bond to N5 (2.462(3) {\AA}). Comparison with the new structurally characterized compd. (BIK)WO2Cl2 (4) (BIK = bis(1-methylimidazol-2-yl)ketone), which has W-N bonds of $\sim$2.30 {\AA}, confirms the unusual length of the W-N bond in 3, probably caused by repulsion between one of the oxo ligands and the peri-hydrogen atom (H6) of DMA. One-electron redn. of the complexes occurs reversibly at room temp. in THF (1, 2) or at 198 K in CH2Cl2 (3). EPR spectroscopy reveals that this process is ligand-centered for 1 and 2 but metal-centered for 3. D. functional methods and ab initio methodol. were used to illustrate the correspondence in spin distribution between the radical anion \textgreek{p} systems of alloxazine and isoalloxazine (flavosemiquinone). [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Hornung, Fridmann M. and Heilmann, Oliver and Kaim, Wolfgang and Zalis, Stanislav and Fiedler, Jan.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/284ea04688426caec5d084720fc739602/huebleriac}, doi = {10.1021/ic0001816}, interhash = {adbf6b76850042fc4fd18a305456be08}, intrahash = {84ea04688426caec5d084720fc739602}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {alloxazine bipyridine bisimidazolylketone chloro chloro;ESR complex;ruthenium copper electrochem imidazolylketone metal oxo phosphine prepn redn;crystal redn;transition redn;tungsten reduced structure transition tungsten}, number = 18, pages = {4052--4058}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Metal vs. Ligand Reduction in Complexes of 1,3-Dimethylalloxazine (DMA) with Copper(I), Ruthenium(II), and Tungsten(VI). Crystal Structures of (DMA)WO2Cl2 and (Bis(1-methylimidazol-2-yl)ketone)WO2Cl2}, volume = 39, year = 2000 }