Self-assembly of non-macrocyclic triangular Ni3Ln clusters

The synthesis and structural characterisation of four new heterometallic tetranuclear complexes is reported. Three L3Ni3Ln type complexes, where Ln = La (C1), Eu (C2), and Gd (C3), have been fully...

Straightforward formation of dianionic acetonylate: self-assembly of mercury(II) with pyridyl donor ligands in acetone

Self-assembly of Hg(ClO4)2 with new bidentate (L) in acetone at room temperature produces single crystals consisting of unusual discrete tetranuclear complexes [Hg4(ClO4)4(CH2COCH2)2L2]·CH3COCH3 via straightforward formation of dianionic acetonylate, -CH2COCH2- in...

Homo- and hetero-metallophilicity-driven synthesis of highly emissive and stimuli-responsive Au(I)-Cu(I) double salts

Complex salts composed of cationic Au(I) and anionic Cu(I) species were synthesized by utilizing bis(diphenylarsino)methane (dpam) and bis(diphenylphosphino)methane (dppm) ligands. The discrete tetranuclear complexes were obtained as crystals, and the...

Investigations of mechanism of Ca2+ adsorption on silica and alumina based on Ca-ISE monitoring, potentiometric titration, electrokinetic measurements and surface complexation modeling

Research on Ca2+ adsorption onto the mineral surface is of significant importance with regard to geochemical processes. Sverjensky (Geochim Cosmochim Acta 70(10), 2427–2453, 2006) assumed that alkaline earths form two types of surface species on oxides: tetranuclear (> SOH)2(> SO−)2_M(OH)+ and mononuclear > SO−_M(OH)+. To look into the above assumption we investigated calcium adsorption on SiO2 and Al2O3 because they are the most widespread minerals in the environment. We have determined the proton surface charge, electrokinetic potential and metal adsorption as a function of pH. The Ca2+ uptake and concentration in the system were monitored by the calcium ion-selective electrode (Ca-ISE). The Ca-ISE measurements indicated a similar affinity of Ca2+ for both materials despite their differently charged surface, negative for silica and mainly positive for alumina. This may suggest that simple electrostatic interactions are not the primary driving force for calcium adsorption, and that solvation of calcium ions at the surface may be crucial. We have analyzed our experimental data using the 2-pK triple-layer model (2-pK TLM). Three calcium complexes on the mineral surface were reported. Two of them were the same for both oxides, i.e. the tetranuclear ($$>$$ > SOH)2($$>$$ > SO−)2_Ca2+ and mononuclear complexes > SO−_CaOH+. Additionally, minor contribution from >SOH…Ca2+ for silica was assumed. In the case of Al2O3 the hydrolyzed tetranuclear complexes ($$>$$ > SOH)2($$>$$ > SO−)2_CaOH+ at pH > 7.5 occurred based on the modeling results. Two types of surface complexes suggested by Sverjensky allowed for the correct description of proton and calcium uptake for alumina. However, the electrokinetic data excluded hydrolyzed tetranuclear surface species for this oxide.

New members of the polynuclear manganese family: MnII2MnIII2 single-molecule magnets and MnII3MnIII8 antiferromagnetic complexes. Synthesis and magnetostructural correlations

Three novel Mn4 and Mn11 complexes were synthesized and characterized. Tetranuclear complexes behave as single-molecule magnets with a high energy barrier.