FTIR and FT-Raman spectra and DFT vibrational analysis of phosphorus-containing dendrons

FTIR and FT-Raman spectra of four generations of phosphorus-containing dendrons with terminal aldehyde or PCl groups have been recorded and analyzed. Their spectral patterns are determined by the ratio T/R (T, the number of terminal groups; R, the number of repeated units). Bands assigned to the core, repeated units and terminal groups were separated by the difference spectroscopy method. The optimized geometry, frequencies and intensity of IR bands of G(1v) generation dendron with terminal aldehyde groups were obtained by the density functional theory (DFT). It was found that the internal skeleton of molecules exists in a single stable conformation with planar O-C(6)H(4)-CHN-N(CH(3))-P(S) fragments, but terminal groups may adopt the t,g,g- and t,-g,g-rotational isomers. The t,-g,g-conformer is 0.74 kcal/mol less stable compared to the t,g,g-conformer. The bond length and bond angles obtained by DFT show the best agreement with experimental data. Relying on DFT calculations a complete assignment of vibrations is proposed for different parts of the studied dendrons. The calculated frequencies and intensity of IR bands of the t,g,g- and t,-g,g-conformers of G(1v) are found to be in reasonable agreement with the experimental results. The most reactive site in dendron is the core function and vinyl group is preferred for nucleophilic attack. In dendrimer the most reactive are the terminal groups.     

Incorporation of a tripodal ligand with a (N,O,O)-donor set into a new family of nickel and cobalt spin clusters

The reaction of Ni(OAc)₂, NiX₂ (X = Cl, Br) or CoCl₂ with the proligand 2-amino-2-methyl-1,3-propanediol (ampdH₂) affords a new family of tetranuclear complexes. The syntheses of [Ni₄(OAc)₄(ampdH)₄] (1) and [M₄X₄(ampdH)₄] (M = Ni, X = Cl, 2; M = Ni, X = Br, 3; M = Co, X = Cl, 4) are reported, together with the single crystal X-ray structures of 1, 2 and 4 and the magnetochemical characterization of 1, 3 and 4. Each member of this family of complexes displays a low symmetry structure that incorporates a {M₄O₄} core unit based on a distorted cubane. Magnetic measurements reveal ferromagnetic exchange interactions for 1, 3 and 4. These give rise to S = 4 ground state spins for the tetranuclear Ni complexes and an anisotropic effective S′ = 2 ground state for the Co complex.     

Assembly between gold-thiolate nanoparticles and the organometallic cluster [Fe(eta5-C5H5)(mu3-CO)]4 toward redox sensing of oxo-anions

Covalent assembly between gold-thiolate nanoparticles (AuNPs) and the cluster [Fe(eta(5)-C(5)H(5))(mu(3)-CO)](4), 1, can be achieved either by direct Brust-Schriffin-type synthesis using a mixture of undecanethiol and a thiol functionalized with , or by substitution of undecanethiolate ligands in AuNPs by thiolate ligands functionalized with ; cyclic voltammetry of these AuNPs functionalized with allows us to recognize and titrate the oxo-anions H(2)PO(4)(-) and ATP(2-).     

Tricarbonylmanganese(I)-lysozyme complex: a structurally characterized organometallic protein

The reaction of the new and structurally characterized covalent {Mn(CO)(3)(H(2)O)(2)}(+)-lysozyme adduct with NiS(4) and NiN(2)S(2) complexes generates binuclear Ni-Mn complexes; relevance to the reactivity of the protein-bound {Fe(CO)(CN)(2)} intermediate during maturation of [NiFe] hydrogenases is discussed.