Synthesis and Characterisation of New {Fe2CrO} Heterotrinuclear Iron-chromium Clusters

Two new μ3-oxo trinuclear heterometallic Fe2IIICrIII complexes with furan-2-carboxylic and salicylic acids with the composition: [Fe2CrO(C4H3OCOO)6(CH3OH)3]NO3·0.5CH3OH and [Fe2CrO(C6H4(OH)COO)7(CH3OH)2]·2DMA were synthesized starting from iron(III) and chromium(III) salts mixture. The complexes structures were confirmed by elemental analysis, IR, Mössbauer spectroscopies, and X-ray analysis. The atomic absorption spectroscopy confirmed that the iron: chromium ratio is 2:1. The thermal properties of both heteronuclear complexes have been investigated in oxidizing and inert atmospheres revealing the stability of the trinuclear core up to 170 and 220°C, respectively.

SYNTHESIS AND SPECTRAL CHARACTERISTICS OF HETEROMETALLIC COMPLEXES OF Pr(III) WITH Zn(II), CO(II) BASED ON ETHYLENEDIAMINETETRAACETIC AND ETHYLENEDIAMINEDISUCCINIC ACIDS

New heterometallic f-d-complexes of Pr (III), Co(II), Zn(II) with aminopolycarboxylic acids (ethylenediaminetetraacetic, ethylenediaminedisuccinic acids) have been synthesized and spectroscopically characterized. It was found that complexes with a molar ratio of Pr:M3d: EDTA=1:2:2 are formed for ethylenediaminetetraacetic compounds, and that in the case of complexes based on EDDS, heteronuclear compounds of the equimolar composition Pr: M3d: EDDS = 1: 1: 1 are formed. It is shown that it is expedient to carry out the synthesis of heterometallic complexes on the basis of mono­nuclear polycarboxylates of 3d metals, which act as a «building block» for the preparation of a heterobinuclear compound by the exo coordination of additional metal ions. The complexes are characterized by the method of electron absorption spectroscopy. It is shown that independent of 3d-metal, for both heterometallic systems based on EDDS, a hypsochromic shift of the absorption maxima relative to νmax is observed for the homonuclear praseodymium complex. For ethylenediaminetetraacetate systems, the absorption maxima undergo both low- and high-frequency shift, which indicates the different nature of the ligand field effect, which is caused primarily by differences in the structure of the corresponding heteronuclearaminopolycarboxylates due to the presence of a chiral carbon atom in the EDDS molecule. For the supersensitive transitions Pr(III)) 3H4 →3P2 and 3H4 → 1D2 , the covalence parameters of the Ln-O bond have been calculated: osci­llator power (P), nepheloxetic parameter (β), covalence parameter (b1/2), Sinha parameter (δ). Analysis of the spectroscopic parameters indicates a decrease in the covalence of the lanthanide-ligand bond in the transition from mono- to heteronuclear complex, and a decrease in the local symmetry of the lanthanide ion occurs in the order Ln (III) aqua ion <hete­rometallic complex <monometallic complex. Heteronuclear complexes are several orders of magnitude more stable than mononuclear ones due to the formation of additional bonds or metallacycles with donor ligand atoms. It is noted that the stability of complexes with EDDS is lower than that of the corresponding complexes with EDTA due to the different size and number of chelated metallacycles. The obtained heteronuclear complexes belong to folded complexes, in which the ligand-complexone realizes the maximum denticity to the lanthanide ion, and the coordination sphere of the 3d-cation is formed by carboxyl groups EDTA / EDDS and inner-sphere water molecules. In this case, the ions of 3d-metals are in a distorted octahedral environment, and the coordination number of Pr(III) is 8.

Modulating carrier transport of Pt-Ag heteronuclear complexes to attain highly efficient OLEDs with narrow-band emission

High color purity with narrow-band emission is a key factor for full-color displays. However, phosphorescent metal complexes typically exhibit broad emission with a full width at half maxima (FWHM) of...

From homonuclear to heteronuclear: a viable strategy to promote and modulate phosphorescence

The use of weakly emissive homonuclear Pt(ii) precursors to fabricate Pt–M heteronuclear complexes with intermetallic contacts paves a unique avenue to achieve highly efficient phosphorescence as well as modulate emission energy.