%0 Journal Article %1 Kaim.1990c %A Kaim, Wolfgang %A Kohlmann, Stephen. %D 1990 %J Inorganic Chemistry %K azopyridine bispyridyltetrazine bridging carbonyl complex complex;MO cyclic electron pi potential system;elec transfer tungsten voltammetry;conjugated %N 10 %P 1898--1902 %R 10.1021/ic00335a027 %T Design and evaluation of conjugated bridging p systems. Molecular orbital characterization and electrochemical determination of the pentacarbonyltungsten binding site in two new ambidentate ligands %V 29 %X Insertion of the strongly p-accepting tetrazine and azo groups between the mol. halves of 4,4'-bipyridine produces the ambidentate nonchelating ligands 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (4,4'-bptz) and 4,4'-azopyridine (4,4'-apy). The p MO calcns. reveal high orbital coeffs. at the N:N p centers in the LUMO of both ligands. The 4,4'-bptz is distinguished by a virtually N(tetrazine) localized LUMO (au) with a nodal plane through the pyridyl substitution centers 3 and 6; however, there exists another very low-lying unoccupied MO (b1u) with appreciable LUMO contribution from the pyridyl rings. The ligands and their bis(pentacarbonyltungsten) complexes were studied by carbonyl vibrational spectroscopy and cyclic voltammetry. These data as well as the ESR results of the singly reduced species can be correlated with the p MO calcns., indicating coordination of the W(CO)5 groups at the less p-accepting, yet more basic and sterically unhindered pyridyl nitrogen centers. A correlation between calcd. LUMO electron densities and the redn. potential differences between the complexes and the free ligands is derived for a no. of dimers (m-L)[W(CO)5]2. The potential use of the two new systems in electron-transfer and mixed-valence chem. is discussed. [on SciFinder(R)]

@article{Kaim.1990c, abstract = {Insertion of the strongly \textgreek{p}-accepting tetrazine and azo groups between the mol. halves of 4,4'-bipyridine produces the ambidentate nonchelating ligands 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (4,4'-bptz) and 4,4'-azopyridine (4,4'-apy). The \textgreek{p} MO calcns. reveal high orbital coeffs. at the N:N \textgreek{p} centers in the LUMO of both ligands. The 4,4'-bptz is distinguished by a virtually N(tetrazine) localized LUMO (au) with a nodal plane through the pyridyl substitution centers 3 and 6; however, there exists another very low-lying unoccupied MO (b1u) with appreciable LUMO contribution from the pyridyl rings. The ligands and their bis(pentacarbonyltungsten) complexes were studied by carbonyl vibrational spectroscopy and cyclic voltammetry. These data as well as the ESR results of the singly reduced species can be correlated with the \textgreek{p} MO calcns., indicating coordination of the W(CO)5 groups at the less \textgreek{p}-accepting, yet more basic and sterically unhindered pyridyl nitrogen centers. A correlation between calcd. LUMO electron densities and the redn. potential differences between the complexes and the free ligands is derived for a no. of dimers (\textgreek{m}-L)[W(CO)5]2. The potential use of the two new systems in electron-transfer and mixed-valence chem. is discussed. [on SciFinder(R)]}, added-at = {2019-07-15T13:41:23.000+0200}, author = {Kaim, Wolfgang and Kohlmann, Stephen.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2dae049bcab46df522e90c9e80bbc4b46/b_schwederski}, doi = {10.1021/ic00335a027}, interhash = {3f701c3a4ea121a1bf0ed5a913413ee7}, intrahash = {dae049bcab46df522e90c9e80bbc4b46}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {azopyridine bispyridyltetrazine bridging carbonyl complex complex;MO cyclic electron pi potential system;elec transfer tungsten voltammetry;conjugated}, number = 10, pages = {1898--1902}, timestamp = {2019-07-15T11:42:10.000+0200}, title = {Design and evaluation of conjugated bridging \textgreek{p} systems. Molecular orbital characterization and electrochemical determination of the pentacarbonyltungsten binding site in two new ambidentate ligands}, volume = 29, year = 1990 }