Heterometallic copper(II)–lead(II), nickel(II)–lead(II) and copper(II)–indium(III) compounds derived from an acyclic double-compartment Schiff base ligand

{1-[1-(2-Hy-droxy-phen-yl)ethyl-idene]-2-(pyridin-2-yl-κN)hydrazine-κ2N',O}{1-[1-(2-oxidophen-yl)ethyl-idene]-2-(pyridin-2-yl-κN)hydrazine-κ2N',O}nickelate(II) nitrate hemihydrate

The 2-hydrazino-pyridine precursor has been widely used to prepare ligands of various kinds by condensation with carbonyl compounds. These types of ligands are suitable for synthesizing novel transition metal (II) complexes with inter-esting magnetic properties. In this context we have synthesized the ligand 1-(2-hy-droxy-phenyl-2-ethyl-idene)-2-(pyridin-2-yl)hydrazine (HL) which was used in the preparation of the mononuclear title complex, [Ni(C13H12N3O)(C13H13N3O)]NO3·0.5H2O. As a result of the presence of HL and L in the [{Ni(HL)(L)}]+ unit, the complex appears to be a supramolecular dimer composed of the Δ(-) and Λ(-) optical isomers, which are linked by strong hydrogen-bonds. As well as the dimer generated by two mononuclear [{Ni(HL)(L)}]+ cations, the asymmetric unit also contains two nitrate anions and one water mol-ecule. Each Ni atom is coordinated to two ligand mol-ecules by a nitro-gen atom of the pyridine ring, an imine nitro-gen atom and a phenolic oxygen atom of one of the ligand mol-ecules and a phenolate oxygen atom of the other organic mol-ecules. The environment around the cation is a distorted octa-hedron. The basal planes are defined by the two nitro-gen atoms of the pyridine rings and the two phenolic oxygen atoms of the ligand, the apical positions being occupied by the azomethine atoms. The O atoms of one of the nitrate ions are disordered over two sets of sites in a 0.745 (9):0.255 (9) ratio. In the crystal, the dimers are linked by numerous hydrogen bonds, forming a three-dimensional framework.

Estimation of conventional C-Hπ (arene), unconventional C-Hπ (chelate) and C-Hπ (thiocyanate) interactions in hetero-nuclear nickel(ii)-cadmium(ii) complexes with a compartmental Schiff base

Three new heteronuclear nickel(ii)/cadmium(ii) complexes, [(SCN)(Cl)Cd(L)Ni(DMF)₂] (1), [(SCN)(CH₃CO₂)Cd(L)Ni(CH₃OH)₂] (2) and [(SCN)(Cl)Cd(L)Ni(NH₂CH₂CH₂CH₂NH₂)]_n (3) {where H₂L = N,N'-bis(3-ethoxy-salicylidene)propane-1,3-diamine is a N₂O₄ compartmental Schiff base}, have been synthesized and characterized. The structures of the complexes have been confirmed by single crystal X-ray diffraction studies. In each complex, nickel(ii) is placed in the inner N₂O₂ environment and cadmium(ii) is placed in the outer O₄ compartment of the compartmental Schiff base. Furthermore, the importance of unconventional C-Hπ (chelate) interactions in the solid state of both complexes and C-Hπ (thiocyanate) interaction in complex 2 has been described by means of DFT and MEP calculations and characterized using NCI plots. All complexes show photoluminescence at room temperature upon irradiation by ultraviolet light. The lifetimes of excited states are in the range of 2-6 ns.

A combined experimental and computational study on supramolecular assemblies in hetero-tetranuclear nickel(ii)-cadmium(ii) complexes with N2O4-donor compartmental Schiff bases

Two new hetero-tetranuclear nickel(ii)/cadmium(ii) complexes, a cubane [(CH₃CO₂)₂Ni₂(L¹)₂Cd₂(NCS)₂] (1) and a linear tetramer [(DMSO)₂NiL²Cd(NCS)(μ_1,3-SCN)Ni(DMSO)L²Cd(NCS)₂] (2) {where H₂L¹ = N,N'-bis(3-methoxysalicylidene)propane-1,3-diamine and H₂L² = N,N'-bis(3-ethoxysalicylidene)propane-1,3-diamine are potential octadentate compartmental Schiff bases}, were synthesized and characterized. The structures of both complexes were confirmed by single crystal X-ray diffraction studies. Complex 1 contained a Ni₂Cd₂O₄ cubane core, whereas complex 2 featured an end-to-end thiocyanate-bridged tetranuclear moiety. Furthermore, complex 1 showed C-HH-C interactions, whereas a unique Sπ interaction was observed in complex 2. Theoretical studies were performed using several computational tools such as NBO and AIM analyses. Both complexes showed photoluminescence in DMSO medium at room temperature upon irradiation with ultraviolet light. The lifetimes of the excited states were ∼27 ns.

Two new 3-D cadmium bromoplumbates: the only example of heterometallic bromoplumbate based on crown [Cd(Pb4O4)Br2] clusters

This work provides the only example of 3-D heterometallic bromoplumbate based on the combination of heterometallic crown [Cd(Pb₄O₄)Br₂] clusters and dimeric [Pb₂Br₄] units.

Non-covalent tetrel bonding interactions in hemidirectional lead(ii) complexes with nickel(ii)-salen type metalloligands

Tetrel bonding interactions have been investigated in hetero-dinuclear nickel(ii)/lead(ii) complexes using MEP and DFT calculations.

Formation of a water-mediated assembly of two neutral copper(ii) Schiff base fragments with a Cu2(NCS)4moiety: exploration of non-covalent C–H⋯π(bimetallo ring) interactions

The energetic features of dimer formation and water encapsulation in an interesting copper(ii) Schiff base complex, [(CuL)₂⊂(H₂O)][Cu₂(μ_1,3-NCS)₂(NCS)₂], have been studied using DFT calculations.