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Krzysztof Chłopek

• In this work the chemistry of the following \(\it {o}\)-phenylenediamine ligands is studied: \(\it {N}\)-phenyl-1,2-benzenediamine (\(\textbf {\(^{1}\)LH\(_{2}\)}\)), \(\it {N}\)-[3,5-di(\(\it {tert}\)-butyl)phenyl]-1,2-benzenediamine (\(\textbf {\(^{2}\)LH\(_{2}\)}\)) and \(\textit {N,N'}\)-substituted \(\textit {N,N'}\)-di[3,5-di(\(\it {tert}\))-butyl)phenyl]-1,2-benzenediamine (\(\textbf {\(^{3}\)LH\(_{2}\)}\)). Iron, nickel and cobalt complexes have been synthesized and characterized spectroscopically and crystallographically. The studies focus on square pyramidal low spin iron(II) and intermediate spin iron(III) complexes containing equatorial \(\it {o}\)-diiminobenzosemiquinonato \(\pi\) radical ligands (derived from \(\textbf {\(^{1}\)LH\(_{2}\)}\) or \(\textbf {\(^{2}\)LH\(_{2}\)}\)) and a neutral or ionic apical ligand (trialkylphosphine, isonitryle, pyridine or iodide). Nickel and cobalt complexes with two deprotonated radical ligands derived from \(\textbf {\(^{3}\)LH\(_{2}\)}\) possess tetrahedral geometry. A +2 physical oxidation state has been found for the Ni compound whereas for the Co complex a +3 physical oxidation number is proposed.