New insights for titanium(iv) speciation in acidic media based on UV-visible and 31P NMR spectroscopies and molecular modeling

A spectroscopic study of titanium(iv) speciation in diluted nitric acid (model of non-complexing medium) and 0.1–12.7 mol L−1 phosphoric acid aqueous solutions. Evidence for the presence of polynuclear species is supported by molecular modeling.

Cathecol and Naphtol Groups in Salphen-Type Schiff Bases for the Preparation of Polynuclear Complexes

In this paper, we show a strategy to modify salphen-type Schiff base ligands with naphtol (SYML1) and pyrocathecol (2,3-dihydroxyphenyl) groups (SYML2), or a combination of both (ASYML). Each of these ligands can be used to obtain polynuclear metal complexes following two different strategies. One relies on using metals that are either too large for the N2O2 cavity or not fond of coordination number 4 and the other one relies on forcing the polynuclear species by adding functional groups to the hydroxybenzaldehayde in order to have extra coordination sites in the ligand. We report and characterize the mononuclear complexes SYML1-Cu and SYML1-Ce, along with the dinuclear complex SYML1-Fe and the tetranuclear species SYML2-Mn. The asymmetric ligand ASYML routinely hydrolyzes into the symmetric ligands in the reaction mixtures. SYML1-Fe displays a nearly linear Fe-O-Fe bridge with very strong antiferromagnetic coupling between the Fe(III) ions.

Homo- and Hetero-Oligonuclear Complexes of Platinum Group Metals (PGM) Coordinated by Imine Schiff Base Ligands

Chemistry of Schiff base (SB) ligands began in 1864 due to the discovery made by Hugo Schiff (Schiff, H., Justus Liebigs Ann. der Chemie 1864, 131 (1), 118–119). However, there is still a vivid interest in coordination compounds based on imine ligands. The aim of this paper is to review the most recent concepts on construction of homo- and hetero-oligonuclear Schiff base coordination compounds narrowed down to the less frequently considered complexes of platinum group metals (PGM). The combination of SB and PGM in oligonuclear entities has several advantages over mononuclear or polynuclear species. Such complexes usually exhibit better electroluminescent, magnetic and/or catalytic properties than mononuclear ones due to intermetallic interactions and frequently have better solubility than polymers. Various construction strategies of oligodentate imine ligands for coordination of PGM are surveyed including simple imine ligands, non-innocent 1,2-diimines, chelating imine systems with additional N/O/S atoms, classic N2O2-compartmental Schiff bases and their modifications resulting in acyclic fused ligands, macrocycles such as calixsalens, metallohelical structures, nano-sized molecular wheels and hybrid materials incorporating mesoionic species. Co-crystallization and formation of metallophilic interactions to extend the mononuclear entities up to oligonuclear coordination species are also discussed.

Rh(iii) hydroxocomplexes speciation using HPLC-ESI-MS

The comprehensive identification of polynuclear species of Rh(iii) was successfully executed by HPLC-ESI-MS combination.

Bi and trinuclear complexes in palladium carboxylate-assisted C–H activation reactions

The role of polynuclear species in C–H activations assisted by palladium carboxylates has not been clear so far.

Trivalent acid radical-centered YLi4+(Y = PO4, AsO4, VO4) cations: new polynuclear species designed to enrich the superalkali family

A new series of polynuclear superalkali cations YLi4+(Y = PO4, AsO4, VO4) has been designed and characterized to enrich the superalkali family.

Extraction behavior of carrier-free and macro amounts of molybdenum and tungsten from HCl solution

Solvent extraction behavior of carrier-free Mo and W from 0.1–11 M HCl into 0.05 M Aliquat 336-chloroform solution was investigated and compared with that of macro amounts of Mo and W. The distribution ratios of carrier-free Mo and W were in good agreement with those of macro amounts of Mo and W in 6–11 M HCl, while the extraction efficiencies of carrier-free Mo and W were different from those of macro amounts of Mo and W in <6 M HCl. Therefore, it appears that the carrier-free as well as macro amounts of Mo and W form mononuclear species in 6–11 M HCl. The disagreement in <6 M HCl is probably due to the formation of polynuclear species of the macro amounts of Mo and W.