%0 Journal Article %1 Maji.2006 %A Maji, Somnath %A Sarkar, Biprajit %A Patra, Srikanta %A Fiedler, Jan %A Mobin, Shaikh M. %A Puranik, Vedavati G. %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2006 %J Inorganic Chemistry %K acetylacetonato complex;ruthenium crystal diiminohydrazido dinuclear electrochem;tetrazine induced opening prepn ring ruthenium structure %N 3 %P 1316--1325 %R 10.1021/ic051532p %T Metal-Induced Reductive Ring Opening of 1,2,4,5-Tetrazines: Three Resulting Coordination Alternatives, Including the New Non-Innocent 1,2-Diiminohydrazido(2-) Bridging Ligand System %V 45 %X Reaction of 3,6-diaryl-1,2,4,5-tetrazines (aryl = R = Ph, 2-furyl or 2-thienyl) with 2 equiv of Ru(acac)2(CH3CN)2 results in reductive tetrazine ring opening to yield diruthenium complexes [(acac)2RuIII(dih-R2-)RuIII(acac)2] bridged by the new 1,2-diiminohydrazido(2-) (dih-R2- = HNC(R)NNC(R)NH2-) ligands. Rac/meso diastereoisomers could be detected and sepd. for the compds. with R = Ph and 2-thienyl, all species are diamagnetic and were characterized by 1H NMR spectroscopy. Crystal structure detn. of the meso isomers with R = Ph and 2-thienyl confirmed the 1,2-diiminohydrazido formulation through long N-N ($\approx$1.40 \AA) and short C:N(H) bonds ($\approx$1.31 \AA), implying two bridged ruthenium(III) centers at $\sim$4.765 \AA distance with strong antiferromagnetic coupling. The complexes undergo two reversible and well-sepd. 1-electron redn. and oxidn. processes, resp. EPR Spectroscopy of the paramagnetic intermediates with comproportionation consts. Kc \textgreater 1012 and UV-visible-NIR spectroelectrochem. were used to identify the accessible redox states as [(acac)2RuII(dih-R2-)RuII(acac)2]2-, [(acac)2RuII(dih-R.bul.-)RuII(acac)2]-, [(acac)2RuIII(dih-R2-)RuIII(acac)2], [(acac)2RuIII(dih-R.bul.-)RuIII(acac)2]+, and [(acac)2RuIII(dih-R)RuIII(acac)2]2+. While the UV-visible-NIR spectroscopic response of [(acac)2Ru(dih-R)Ru(acac)2]0/-/2- is very similar to that of [(bpy)2Ru(adc-R)Ru(bpy)2]4+/3+/2+, adc-R2- = 1,2-diacylhydrazido(2-), the EPR result indicating ligand-centered spin for [(acac)2RuII(dih-R.bul.-)RuII(acac)2]- despite deceptive NIR absorptions around 1400 nm reveals distinct differences in the electronic structures. [on SciFinder(R)]

@article{Maji.2006, abstract = {Reaction of 3,6-diaryl-1,2,4,5-tetrazines (aryl = R = Ph, 2-furyl or 2-thienyl) with 2 equiv of Ru(acac)2(CH3CN)2 results in reductive tetrazine ring opening to yield diruthenium complexes [(acac)2RuIII(dih-R2-)RuIII(acac)2] bridged by the new 1,2-diiminohydrazido(2-) (dih-R2- = HNC(R)NNC(R)NH2-) ligands. Rac/meso diastereoisomers could be detected and sepd. for the compds. with R = Ph and 2-thienyl, all species are diamagnetic and were characterized by 1H NMR spectroscopy. Crystal structure detn. of the meso isomers with R = Ph and 2-thienyl confirmed the 1,2-diiminohydrazido formulation through long N-N ($\approx$1.40 {\AA}) and short C:N(H) bonds ($\approx$1.31 {\AA}), implying two bridged ruthenium(III) centers at $\sim$4.765 {\AA} distance with strong antiferromagnetic coupling. The complexes undergo two reversible and well-sepd. 1-electron redn. and oxidn. processes, resp. EPR Spectroscopy of the paramagnetic intermediates with comproportionation consts. Kc {\textgreater} 1012 and UV-visible-NIR spectroelectrochem. were used to identify the accessible redox states as [(acac)2RuII(dih-R2-)RuII(acac)2]2-, [(acac)2RuII(dih-R.bul.-)RuII(acac)2]-, [(acac)2RuIII(dih-R2-)RuIII(acac)2], [(acac)2RuIII(dih-R.bul.-)RuIII(acac)2]+, and [(acac)2RuIII(dih-R)RuIII(acac)2]2+. While the UV-visible-NIR spectroscopic response of [(acac)2Ru(dih-R)Ru(acac)2]0/-/2- is very similar to that of [(bpy)2Ru(adc-R)Ru(bpy)2]4+/3+/2+, adc-R2- = 1,2-diacylhydrazido(2-), the EPR result indicating ligand-centered spin for [(acac)2RuII(dih-R.bul.-)RuII(acac)2]- despite deceptive NIR absorptions around 1400 nm reveals distinct differences in the electronic structures. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Maji, Somnath and Sarkar, Biprajit and Patra, Srikanta and Fiedler, Jan and Mobin, Shaikh M. and Puranik, Vedavati G. and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2e911cfa6a076cb23c9feb87a375f9702/huebleriac}, doi = {10.1021/ic051532p}, interhash = {6f001ef897f74cb73ba45e5296398ebc}, intrahash = {e911cfa6a076cb23c9feb87a375f9702}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {acetylacetonato complex;ruthenium crystal diiminohydrazido dinuclear electrochem;tetrazine induced opening prepn ring ruthenium structure}, number = 3, pages = {1316--1325}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Metal-Induced Reductive Ring Opening of 1,2,4,5-Tetrazines: Three Resulting Coordination Alternatives, Including the New Non-Innocent 1,2-Diiminohydrazido(2-) Bridging Ligand System}, volume = 45, year = 2006 }