Five-Coordinated Geometries from Molecular Structures to Solutions in Copper(II) Complexes Generated from Polydentate-N-Donor Ligands and Pseudohalides

A novel series of mononuclear five-coordinated pseudohalido-Cu(II) complexes displaying distorted square bipyramidal: [Cu(L¹)(NCS)₂] (1), [Cu(L²)(NCS)₂] (2) and [Cu(L³)(NCS)]ClO₄ (5) as well as distorted trigonal bipyramidal: [Cu(isp₃tren)(N₃)]ClO₄ (3), [Cu(isp₃tren)(dca)]ClO₄ (4) and [Cu(tedmpza)(dca)]ClO₄·0.67H₂O (6) geometries had been synthesized and structurally characterized using X-ray single crystal crystallography, elemental microanalysis, IR and UV-vis spectroscopy, and molar conductivity measurements. Different N-donor amine skeletons including tridentate: L¹ = [(2-pyridyl)-2-ethyl)-(3,4-dimethoxy)-2-methylpyridyl]methylamine and L² = [(2-pyridyl)-2-ethyl)-(3,5-dimethyl-4-methoxy)-2-methyl-pyridyl]methylamine, and tetradentate: L³ = bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl)-[2-(3,4-dimethoxy-pyridylmethyl)]amine, tedmpza = tris[(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]amine and isp₃tren = tris[(2-isopropylamino)ethyl)]amine ligands were employed. Molecular structural parameters such as nature of coligand, its chelate ring size and steric environment incorporated into its skeleton, which lead to adopting one of the two limiting geometries in these complexes and other reported compounds are analyzed and correlated to their assigned geometries in solutions. Similar analysis were extended to other five-coordinated halido-Cu(II) complexes.

Impact of the synthetic approach on the magnetic properties and homogeneity of mixed crystals of tunable layered ferromagnetic coordination polymers

Different synthetic routes were applied to synthesize mixed crystals of [Co_xNi_1−x(NCS)₂(4-tert-butylpyridine)₂]_n that finally results in homogeneous samples for which the critical temperature can be tuned as function of the Co : Ni ratio.

Designing antiferromagnetically coupled mono-, di- and tri-bridged copper(ii)-based catecholase models by varying the ‘Auxiliary Parts’ of the ligand and anionic co-ligand

The role of the auxiliary part of ligands towards the architecture of copper(ii)-based catecholase models were unveiled with the help of DFT study.

Formation of di- and polynuclear Mn(II) thiocyanate pyrazole complexes in solution and in the solid state

Reaction of Mn(NCS)2 with pyrazole leads to the formation of three compounds with the compositions Mn(NCS)2(pyrazole)4 (1), [Mn(NCS)2]2(pyrazole)6 (2) and Mn(NCS)2(pyrazole)2 (3). Compound 1, already reported in the literature, consists of discrete complexes, in which the Mn(II) cations are octahedrally coordinated by four pyrazole ligands and two terminally N-bonded thiocyanate anions. In compound 2 each of the two Mn(II) cations are coordinated octahedrally by three pyrazole ligands and one terminal as well as two bridging thiocyanate anions, which link the metal cations into dimers. In compound 3 also octahedrally coordinated Mn(II) cations are present but they are linked into chains via centrosymmetric pairs of μ-1,3-bridging thiocyanate anions. Upon heating compound 1 loses the pyrazole co-ligands stepwise and is transformed into the chain compound 3 via the dimer 2 that is formed as an intermediate. Magnetic measurements on compounds 2 and 3 reveal dominating antiferromagnetic interactions, as already observed for 1D Mn(NCS)2 coordination compounds with pyridine based co-ligands.

Cd(II) and Zn(II) thiocyanate coordination compounds with 3-ethylpyridine: synthesis, crystal structures and properties

Reaction of Cd(NCS)2 and Zn(NCS)2 with 3-ethylpyridine leads to the formation of compounds of compositions M(NCS)2(3-ethylpyridine)4 (M=Cd, 1-Cd; Zn, 1-Zn) and M(NCS)2(3-ethylpyridine)2 (M=Cd, 2-Cd; Zn, 2-Zn). 1-Cd and 1-Zn are isotypic and form discrete complexes in which the metal cations are octahedrally coordinated by two trans-coordinating N-bonded thiocyanate anions and four 3-ethylpyridine co-ligands. In 2-Cd the cations are also octahedrally coordinated but linked into chains by pairs of μ-1,3-bridging anionic ligands. 2-Zn is built up of discrete complexes, in which the Zn cation is tetrahedrally coordinated by two N-bonded thiocyanate anions and two 3-ethylpyridine co-ligands. Compounds 1-Cd, 2-Cd and 2-Zn can be prepared in a pure state, whereas 1-Zn is unstable and transforms on storage into 2-Zn. If 1-Cd and 1-Zn are heated, a transformation into 2-Cd, respectively 2-Zn is observed. Luminescence measurements reveal that 1-Cd, 2-Cd and 2-Zn emit light in the blue spectral range with maxima at, respectively, 21724, 21654 and 22055 cm−1, assigned to ligand-based luminescence.

N9 substituent mediated structural tuning of copper–purine complexes: chelate effect and thin film studies

Six Cu(ii) complexes of strategically designed derivatives of 6-chloropurine, one of which has been explored as a thin film precursor on quartz and Si(111) surfaces by using chemical vapor deposition (CVD).