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
(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)
%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
}
