Propeller-like heterotrinuclear CuII–LnIII–CuII compounds – Physicochemical properties

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.

A new co-crystal dinuclear/trinuclear ZnII-ZnII/ZnII-SmIII-ZnII complex with a salen-type Schiff base ligand

In the penta-nuclear title complex, [SmZn2(C22H18N2O4)2(NCS)2(C3H7NO)2][Zn2(C22H18N2O4)(NCS)3]·C3H7NO·0.32H2O, namely bis-{μ2-6,6'-dimeth-oxy-2,2'-[phenyl-ene-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}-1κ4 O,N,N',O':2κ3 O,O',O 6;2κ3 O,O',O 6:3κ4 O,N,N',O'-bis-(di-methyl-formamide-2κO)di-thiocyanato-1κN,3κN-2-samarium(III)-1,3-dizinc(II) {μ2-6,6'-dimeth-oxy-2,2'-[phenyl-ene-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-1κ4 O,N,N',O':2κ2 O,O'}trithio-cyan-ato-1κN;2κ2 N,N-dizinc(II) di-methyl-formamide monosolvate 1.32-hydrate, a dinuclear unit and a trinuclear unit co-exist. One of the ZnII centers in the dinuclear unit as well as the two ZnII centers in the trinuclear unit are located in the inner N2O2 cavity of the ligand and are coordinated to the nitro-gen atom of one thio-cyanate moiety, giving rise to a square-pyramidal geometry. The second ZnII center in the dinuclear unit is coordinated to the two phenolate oxygen atoms of the ligand and to two thio-cyanate groups via the nitro-gen atom in a tetra-hedral geometry. The SmIII ion is eight-coordinated by four phenolate O atoms from the two ligand mol-ecules, two meth-oxy O atoms from the two ligand mol-ecules and two O atoms from the DFM solvent mol-ecule. In the dinuclear unit, the two meth-oxy oxygen atoms remain uncoordinated while in the trinuclear unit, for each ligand one meth-oxy oxygen is coordinated and the other one remains uncoordinated. In the crystal, the trinuclear cationic units and dinuclear anionic units are assembled into infinite layers. These layers are held together via electrostatic inter-actions, forming a three-dimensional structure. In the dinuclear unit, the C and S atoms of one of the thio-cyanate groups are disordered over two sets of sites in a 0.680 (4)(4):0.320 (4) ratio.

Chromatographic Study of Novel Heteronuclear Complexes with Schiff Base as Main Ligand

The properties of 12 new heterodi- and heterotrinuclear complexes having general formulae [Cu2Ln(L)2(NO3)(H2O)2](NO3)2·3H2O [where Ln = Pr (1), Nd (2), Sm (3) and Eu (4)], and [CuLn(L)(NO3)2(H2O)3MeOH]NO3·MeOH [where Ln = Gd (5), Tb (6), Dy (7), Ho (8), Ef (9), Tm (10), Yb (11) and Lu (12)], and their main ligand [L = C19H18N2O4Br2 = N,N'-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine] have been characterized by chromatographic analyses. The parameter of relative lipophilicity (RM0) of the tested compounds was determined experimentally by reversed-phase high-performance thin layer chromatography method with mixtures of methanol and water as a mobile phase. We also described interactions between chromatographed substances and various surfaces (silica-SiO2 and modified by hydrocarbon chains-RP-2, RP-8, RP-18 phases). This study also investigates the effect of pH of the mobile phase on the retention on the polar stationary phase. Thin layer chromatography combined with magnetic and electric field has been proposed as a complementary method for the determination of physicochemical properties of the investigated compounds. The chromatograms in the field and outside of it were developed simultaneously in three identical chromatographic chambers. One of them was placed in external magnetic field of 0.4 T inductivity, and the second in external electrical field. In magnetic and electric fields, retention of some complexes changed, which indicated that the presence of these fields influenced physicochemical properties of the compounds and their interactions with the stationary phase.