Rhodium and iridium amino, amido, and aminyl radical complexes

Donati, Nicola, Stein, Daniel, Buettner, Torsten, Schoenberg, Hartmut, Harmer, Jeffrey, Anadaram, Sreekanth and Gruetzmacher, Hansjoerg (2008) Rhodium and iridium amino, amido, and aminyl radical complexes. European Journal of Inorganic Chemistry, 30: 4691-4703. doi:10.1002/ejic.200800702


Author Donati, Nicola
Stein, Daniel
Buettner, Torsten
Schoenberg, Hartmut
Harmer, Jeffrey
Anadaram, Sreekanth
Gruetzmacher, Hansjoerg
Title Rhodium and iridium amino, amido, and aminyl radical complexes
Journal name European Journal of Inorganic Chemistry   Check publisher's open access policy
ISSN 1434-1948
1099-0682
Publication date 2008-10
Sub-type Article (original research)
DOI 10.1002/ejic.200800702
Issue 30
Start page 4691
End page 4703
Total pages 13
Place of publication Weinheim, Germany
Publisher Wiley
Language eng
Formatted abstract
The chlorido-bridged dimeric complex [Rh2(μ-Cl)2(trop2NH)2] [trop2NH = bis(benzo[a,d]cycloheptenyl)amine] or the acetonitrile complexes [Rh(trop2NH)(MeCN)2]+ (CF3SO3–) and [IrCl(MeCN)(trop2NH)] are well-suited precursor complexes for phenanthroline-type complexes [M(trop2NH)(R,R-phen)]+A (M = Rh, Ir; R = H, Me, Ph substituents in the 4,7- or 5,6-positions of the phen ligand, A– = CF3SO3–, PF6–). 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=Ctrop units is in an equatorial position. The cationic amino complexes [M(trop2NH)(R,R-phen)]+ are sufficiently acidic (pKa in dmso: 18.2–19.0) to be quantitatively deprotonated by one equivalent of KOtBu to give neutral amido complexes [M(trop2N)(R,R-phen)] (M = Rh, Ir). These can be easily oxidized to give aminyl radical complexes [M(trop2N·)(R,R-phen)]+A–, which for M = Rh can be isolated as green crystals. The iridium complex [Ir(trop2N·)(phen)]+ 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(trop2N·)(phen)]+: g1,2,3 = 2.084(2), 2.049(2), 2.027(2); |Aiso| = 45.4 (N1), 10.4 (N2), 3.1 (N3) 27.0 (Rh) MHz; [Ir(trop2N·)(phen)]+: g1,2,3 = 2.140(2), 2.107(2), 2.015(2); |Aiso| = 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 trop2N ligand. In reactions with stannanes (R3SnH) and thiols (RSH), H-atom transfer to the trop2N nitrogen atom is observed, [M(trop2N·)(phen)]+ + EH → [M(trop2NH)(phen)]+ + 1/2HE–EH.
Keyword Cyclic voltammetry
Iridium
Organometallic compounds
Phosphanes
Reaction mechanisms
Rhodium
Bond-Dissociation Energies
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Advanced Imaging Publications
 
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