Klaus von Deuten

Bio: Klaus von Deuten is an academic researcher from University of Hamburg. The author has contributed to research in topics: Crystal structure & Metallacycle. The author has an hindex of 6, co-authored 10 publications receiving 111 citations.

Cyclometallation reactions inortho-methyl substituted iridium arylsvia CO insertion and oxidative C-H addition. Characterization of the reported IrH[C6H2Me2-(4,6)-CH2-(2)][P(OMe)3]3 as the internally metallated benzoyl complexfac-IrH[C(O)C6H2Me2-(4,6)-H2(2)]-[P(OMe)3]3 by X-Ray diffraction(1)

Abstract: The title compound, previously reported as , has been characterized as by x-ray analysis. The complex crystallizes in the triclinic space group P1 witha = 1029.2(4),b = 1192.7(7),c = 1216.6(7) pm, α = 105.42(4), β = 105.95(4), γ = 95.45(4)°, and Z = 2. With 3909 independent reflections for which F0 > 3 σ(F0,), the structure has been refined anisotropically to R = 0.048. The molecular geometry corresponds to a distorted octahedron with the phosphite ligands infac positions. The complex contains a five-membered metallocycle of the iridaindanone type, , in which the metal deviates slightly from the plane defined by the carbon atoms. Important bond distances are Ir-P = 230.1(3), 230.6(4), and 228.0(3) pm, Ir-C(O) = 207(1) pm, and Ir-CH2 = 213(1) pm. On the basis of the x-ray results and further i.r. and13C n.m.r. data, the structures of a series of related complexes, previously regarded as , have also been reformulated as .

X-Ray Crystal Structure Analysis of Factor A (2-Methyladeninyl-cyanocobamide), a Native Vitamin B12-Analogue

Abstract: Vitamin B12-factor A (2-Methyladeninyl-cyanocobamide), Vitamin B12, X-Ray Crystal Structure Analysis The crystal and molecular structure of 2-methyladeninyl-cyanocobamide (factor A) has been determined. This compound crystallizes in space group P21212, with a = 2630.6 (15), b = 2210.6 (13) and c = 1592.1 (9) pm. The structure has been solved by the heavy-atom method and refined by least-squares methods on the basis of 3682 X-ray counter data to R = 0.166 and R w = 0.148. As far as we know, this is the first X-ray-investigation of a purine-corrinoid, which differs from cyanocobalamin (vitamin B12) by containing a purine base instead of 5,6-dimethylbenz-imidazole. The structure analysis of 2-methyladeninyl-cyanocobamide shows unambiguously, that the purine base coordinates with cobalt via N B9. The choice of N B9 as coordinative atom can be ascribed partly (or mainly?) to steric influences, since coordination via N B3, which was also discussed, would presumably lead to severe distortion of the nucleotide loop.

1,4-Diaza-1,3-butadiene (a-diimine) ligands: their coordination modes and the reactivity of their metal complexes

Abstract: Publisher Summary Molecules containing the 1,4-diaza-1,3-butadiene skeleton have attracted much interest because of both their versatile coordination behavior and the interesting properties of their metal complexes. 1,4-diaza-1,3-butadienes (R-DAB) may be prepared by condensation reactions involving glyoxals, α-ketoaldehydes or α, β-–diketones with primary amines RNH2. It was concluded from nuclear magnetic resonance (NMR) spectra, dipole moments, and infrared (IR) spectra that the R-DAB molecule exists in solution in the E configuration at both C=N double bonds while the conformation of the central C–C bond is predominantly s-trans. So far stable complexes containing monodentate R–DAB have only been reported for the square planar d8–metals Pd11, Pt11, and Rh1. The reports of metal complexes with R–DAB ligands date back to 1953 when Krumholz described the synthesis of some ferrous complexes. The unusual stability and characteristic color being ascribed to the presence of π bonding between the metal and the nitrogen atoms. Factors, such as the substituents R and R, the metal atom, and the other ligands bonded to the metal atom, will influence the type of coordination of the R–DAB( R’,R) ligands. Just as 2, 2’-bipyridine, the R–DAB ligands can be readily converted to stable paramagnetic radical anions by potassium in 1,2-dirnethoxyethane or tetrahydrofuran (THF).

Crown thioether chemistry

Abstract: The synthetic, structural, and coordination chemistry of crown thioethers with both transition and p-block metal ions is reviewed comprehensively through December 1988. Emphasis falls upon the electronic structures and redox properties induced in metal ions by coordination to crown thioethers. Examples include stabilization of mononuclear Rh(II), Pt(III), and low-spin octahedral Co(II). A subsidiary theme concerns the influence of ligand conformation in determining both the binding efficacy and the qualitative coordination chemistry associated with a given crown thioether. The review concludes with a view toward potential future applications of crown thioethers in catalysis, in sequestration or biological delivery of heavy metal ions, and in fundamental studies directed toward rational design of ligands.