%0 Journal Article %1 Klein.1995b %A Klein, Axel %A Kaim, Wolfgang %A Waldhoer, Eberhard %A Hausen, Hans-Dieter. %D 1995 %J Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry %K ESR anion complex crystal dimesityl mesityl mol phenanthroline platinum platinum;phenanthroline potential;radical redox structure %N 12 %P 2121--2126 %T Different orbital occupation by an added single electron in 1,10-phenanthroline and its 3,4,7,8-tetramethyl derivative. Evidence from electron paramagnetic resonance spectroscopy of the anion radicals and of their dimesitylplatinum(II) complexes. X-ray molecular structure of dimesityl(1,10-phenanthroline)platinum(II) %X In contrast to the anion radicals of 1,10-phenanthroline (phen) or its 4,7-di-Me deriv. (dmphen) with their 2B1 ground state, the 3,4,7,8-tetra-Me deriv. tmphen·- has a 2A2 ground state as evident from EPR/ENDOR measurements. The small p spin population at the potentially metal-coordinating nitrogen centers in the 2A2 species as opposed to the 2B1 state causes distinct spectroscopic effects in corresponding diorganoplatinum(II) complexes. The neutral compd. (phen)PtMes2, mes = mesityl, has been structurally characterized as a square planar PtII complex with tightly protected axial sites: monoclinic, space group P21/c, Z = 4, a = 9.378(1), b = 15.791(2), c = 16.581(1) \AA, b = 103.18(1)°. All complexes (NLN)PtMes2, NLN = bpy (2,2'-bipyridine), phen, tmphen, dppz (dipyrido3,2-a:2',3'-cphenazine) and pdo (1,10-phenanthroline-5,6-dione) are oxidized to EPR-silent platinum(III) species and reduced to anion radical complexes. The latter clearly contain PtII and heterocyclic anion radical ligands; however, they exhibit a trichotomous EPR behavior. Whereas the radical complex (phen)PtMes2·- shows a rather low giso-value of 1.983 and distinct g anisotropy in frozen soln. like the analogous complex of bpy·-, the formally related (tmphen)PtMes2·- has an isotropic g-factor (2.0030) much closer to the free-electron value and a distinctly smaller g anisotropy. The phenanthroline-derived radical complexes (pdo)PtMes2·- and (dppz)PtMes2·- exhibit virtually no contribution from the coordinated heavy metal to the singly occupied MO (b1) which is mainly centered at the heteroatoms outside the phenanthroline P system. on SciFinder(R)

@article{Klein.1995b, abstract = {In contrast to the anion radicals of 1,10-phenanthroline (phen) or its 4,7-di-Me deriv. (dmphen) with their 2B1 ground state, the 3,4,7,8-tetra-Me deriv. tmphen·- has a 2A2 ground state as evident from EPR/ENDOR measurements. The small \textgreek{p} spin population at the potentially metal-coordinating nitrogen centers in the 2A2 species as opposed to the 2B1 state causes distinct spectroscopic effects in corresponding diorganoplatinum(II) complexes. The neutral compd. (phen)PtMes2, mes = mesityl, has been structurally characterized as a square planar PtII complex with tightly protected axial sites: monoclinic, space group P21/c, Z = 4, a = 9.378(1), b = 15.791(2), c = 16.581(1) {\AA}, \textgreek{b} = 103.18(1)°. All complexes (N\textgreek{L}N)PtMes2, N\textgreek{L}N = bpy (2,2'-bipyridine), phen, tmphen, dppz (dipyrido[3,2-a:2',3'-c]phenazine) and pdo (1,10-phenanthroline-5,6-dione) are oxidized to EPR-silent platinum(III) species and reduced to anion radical complexes. The latter clearly contain PtII and heterocyclic anion radical ligands; however, they exhibit a trichotomous EPR behavior. Whereas the radical complex [(phen)PtMes2]·- shows a rather low giso-value of 1.983 and distinct g anisotropy in frozen soln. like the analogous complex of bpy·-, the formally related [(tmphen)PtMes2]·- has an isotropic g-factor (2.0030) much closer to the free-electron value and a distinctly smaller g anisotropy. The phenanthroline-derived radical complexes [(pdo)PtMes2]·- and [(dppz)PtMes2]·- exhibit virtually no contribution from the coordinated heavy metal to the singly occupied MO (b1) which is mainly centered at the heteroatoms outside the phenanthroline P system. [on SciFinder(R)]}, added-at = {2019-07-15T13:41:23.000+0200}, author = {Klein, Axel and Kaim, Wolfgang and Waldhoer, Eberhard and Hausen, Hans-Dieter.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2468d41d603eb91a42dbc653c9ce97b84/b_schwederski}, interhash = {feec3861662de45b7bf39eb564a76d0d}, intrahash = {468d41d603eb91a42dbc653c9ce97b84}, issn = {0300-9580}, journal = {Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry}, keywords = {ESR anion complex crystal dimesityl mesityl mol phenanthroline platinum platinum;phenanthroline potential;radical redox structure}, number = 12, pages = {2121--2126}, timestamp = {2019-07-15T11:42:10.000+0200}, title = {Different orbital occupation by an added single electron in 1,10-phenanthroline and its 3,4,7,8-tetramethyl derivative. Evidence from electron paramagnetic resonance spectroscopy of the anion radicals and of their dimesitylplatinum(II) complexes. X-ray molecular structure of dimesityl(1,10-phenanthroline)platinum(II)}, year = 1995 }