Rhodium and Iridium Amino, Amido, and Aminyl Radical Complexes

<jats:title>Abstract</jats:title><jats:p>The chlorido‐bridged dimeric complex [Rh<jats:sub>2</jats:sub>(<jats:italic>μ</jats:italic>‐Cl)<jats:sub>2</jats:sub>(trop<jats:sub>2</jats:sub>NH)<jats:sub>2</jats:sub>] [trop<jats:sub>2</jats:sub>NH = bis(benzo[<jats:italic>a,d</jats:italic>]cycloheptenyl)amine] or the acetonitrile complexes [Rh(trop<jats:sub>2</jats:sub>NH)(MeCN)<jats:sub>2</jats:sub>]<jats:sup>+</jats:sup>(CF<jats:sub>3</jats:sub>SO<jats:sub>3</jats:sub><jats:sup>–</jats:sup>) and [IrCl(MeCN)(trop<jats:sub>2</jats:sub>NH)] are well‐suited precursor complexes for phenanthroline‐type complexes [M(trop2NH)(R,R‐phen)]<jats:sup>+</jats:sup>A<jats:sup>–</jats:sup>(M = Rh, Ir; R = H, Me, Ph substituents in the 4,7‐ or 5,6‐positions of the phen ligand, A<jats:sup>–</jats:sup>= CF<jats:sub>3</jats:sub>SO<jats:sub>3</jats:sub><jats:sup>–</jats:sup>, PF<jats:sub>6</jats:sub><jats:sup>–</jats:sup>). These complexes contain 18‐valence‐electron configured metal centers in a trigonal–bipyramidal coordination sphere with the amino (NH) group in an axial position and each of the olefinic C=C<jats:sub>trop</jats:sub>units is in an equatorial position. The cationic amino complexes [M(trop<jats:sub>2</jats:sub>NH)(R,R‐phen)]<jats:sup>+</jats:sup>are sufficiently acidic (p<jats:italic>K</jats:italic><jats:sub>a</jats:sub>in dmso: 18.2–19.0) to be quantitatively deprotonated by one equivalent of KO<jats:italic>t</jats:italic>Bu to give neutral amido complexes [M(trop<jats:sub>2</jats:sub>N)(R,R‐phen)] (M = Rh, Ir). These can be easily oxidized to give aminyl radical complexes [M(trop<jats:sub>2</jats:sub>N<jats:sup><jats:bold>·</jats:bold></jats:sup>)(R,R‐phen)]<jats:sup>+</jats:sup>A<jats:sup>–</jats:sup>, which for M = Rh can be isolated as green crystals. The iridium complex [Ir(trop<jats:sub>2</jats:sub>N<jats:sup><jats:bold>·</jats:bold></jats:sup>)(phen)]<jats:sup>+</jats:sup>is unstable. High‐resolution pulse EPR spectroscopy was used to gain insight into the electronic structure of the aminyl radical complexes. Remarkably, the rhodium and iridium complexes have a very similar electronic structure, as revealed by their EPR parameters {[Rh(trop<jats:sub>2</jats:sub>N<jats:sup><jats:bold>·</jats:bold></jats:sup>)(phen)]<jats:sup>+</jats:sup>:<jats:italic>g</jats:italic><jats:sub>1,2,3</jats:sub>= 2.084(2), 2.049(2), 2.027(2);<jats:italic>|A</jats:italic><jats:sub>iso</jats:sub>| = 45.4 (N1), 10.4 (N2), 3.1 (N3) 27.0 (Rh) MHz; [Ir(trop<jats:sub>2</jats:sub>N<jats:sup><jats:bold>·</jats:bold></jats:sup>)(phen)]<jats:sup>+</jats:sup>:<jats:italic>g</jats:italic><jats:sub>1,2,3</jats:sub>= 2.140(2), 2.107(2), 2.015(2);<jats:italic>|A</jats:italic><jats:sub>iso</jats:sub>| = 47 (N1), 7.9 (N2), 3.5 (N3), 26.8 (Ir) MHz} and these show that about 60 % of the spin population is localized on the nitrogen center (N1) of the trop<jats:sub>2</jats:sub>N ligand. In reactions with stannanes (R<jats:sub>3</jats:sub>SnH) and thiols (RSH), H‐atom transfer to the trop<jats:sub>2</jats:sub>N nitrogen atom is observed, [M(trop<jats:sub>2</jats:sub>N<jats:sup><jats:bold>·</jats:bold></jats:sup>)(phen)]<jats:sup>+</jats:sup>+ EH → [M(trop<jats:sub>2</jats:sub>NH)(phen)]<jats:sup>+</jats:sup>+ 1/2HE–EH.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)</jats:p>