A Novel Tetranuclear Silver Compound with bis(3,5-dimethylpyrazol-1-yl)acetate: a Simple Synthesis Yielding Complex Crystal Structure.

A novel tetranuclear silver coordination compound with the formula [Ag4(bdmpza)4]×10H2O (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate) was synthesized by a reaction between an aqueous solution of silver nitrate and an aqueous solution prepared by bis(3,5-dimethylpyrazol-1-yl)acetic acid and potassium hydroxide (1:1 molar ratio). The obtained compound was characterized by elemental analysis, coupled thermogravimetric-mass spectrometry analysis, vibrational IR spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction method. Furthermore, the obtained crystal structure was additionally evaluated by Hirshfeld surface analysis.

New Zinc Coordination Compound with Simple Salicylato and Pyridine Ligands: Synthesis, Crystal Structure and Hirshfeld Surface Analysis.

A novel mononuclear zinc coordination compound with formula [Zn(Hsal)2(Py)2] (H2sal = salicylic acid, Py = pyridine) was prepared by mixing aqueous solutions of sodium salicylate and zinc sulfate in 1:1 molar ratio, and to the resulting solution pyridine was added dropwise. The obtained compound was characterized by elemental analysis, IR spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction method. X-ray structure analysis has shown that the central zinc ion is four-coordinated by two monodentate salicylato ligands and two pyridine molecules, forming a distorted tetrahedron. Since the asymmetric unit consists of two halves of coordination molecules, orthorhombic Ibca space group symmetry leads to two coordination molecules with slightly different geometry. The comparison between the two is given in terms of interatomic distances and angles, and also in terms of differences in intermolecular interactions obtained as a result of Hirshfeld surface analysis. With the assistance of C-H…O interactions, the adjacent molecules are linked into chains and further connected into three-dimensional network.

[MII(NCS)2(nia)2(OH2)2]: Preparation, Crystal Structure and Thermal Properties (MII = Mn, Fe; nia = nicotinamide).

Two novel isostructural coordination compounds of manganese(II) (1) and iron(II) (2) with common formulae [MII(NCS)2(nia)2(OH2)2] have been prepared from water solution of appropriate metal salt, nicotinamide and KSCN. Their crystal structures were determined by means of X-ray diffraction on single crystals. The mononuclear title compounds crystallize in a triclinic P-1 space group with six monodentate octahedrally arranged ligands around the metal centre. The coordination molecules are self-assembled with an extended network of hydrogen bonds into a three-dimensional structure. Additionally, 1 and 2 were characterized with infrared spectroscopy, magnetic measurements and thermal analysis.

Stability of the compounds with the octahedral [MII(κ3-L)2] coordination building blocks of late 3d elements via solvate water supramolecular arrangement.

Five new coordination compounds with the common formulae [MII(bdmpza)2]•xH2O (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate, C11H15N4COO-; x = 2 for Co (1), Ni (2) and Zn (3), x = 3 for Mn (4) and Fe (5)), were synthesized from the reaction mixtures containing appropriate metal salt, bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza), methanol and water. The X-ray single crystal diffraction analysis reveals that all five compounds (1-5) contain mononuclear homoleptic [MII(bdmpza)2] coordination molecules, in which the central metal ions are surrounded with two chelating bdmpza ligands. Each ligand is bound tridentately facially via κ3-N,N,O sites and centrosymmetric coordination chromophore is thus obtained. In the dihydrates [M(L)2]•2H2O, 1-3, every coordination molecule is linked by two water molecules, i.e. two pairs of O-H...O hydrogen bonds, on each of the two sides, thus forming infinite chain. In case of the trihydrates [M(L)2]•3H2O, 4-5, with an assistance of the additional water molecule, such chains are further connected into extended supramolecular sheets. A similarity of both hydrate types is confirmed by powder XRD data and IR analysis. The ionic metal radius and the coordination M-O, M-N bonds were related to the void dimension among the coordination molecules of the title [MII(bdmpza)2]•xH2O.

Cis-trans isomeric and polymorphic effects on the magnetic properties of water-bridged copper coordination chains.

The synthesis and magnetic characterization of vanillin-based Cu(II) mononuclear complexes of formula [Cu(van)(2)(H(2)O)(2)](H(2)O)(x) (van = vanillinate; x = 0, compound 1; x = 2, compounds 2 and 3) were performed. Despite the presence of very similar [Cu(van)(2)(H(2)O)(2)] moieties, the crystal structures exhibit distinct Cu···Cu contacts and display three different through-H-bond exchange-coupling pathways. As a result of the relative positions of the water molecules, the experimental (MAGSUS) exchange-coupling constants are dissimilar, i.e., J(1) = -3.0 cm(-1) (the data have been fitted to the Bleaney-Bowers equation considering a dimer; 2J = -6.0 cm(-1)), J(2) = -4.0 cm(-1) (the data have been fitted to the Bonner-Fischer equation for a chain of monomeric copper(II) units), whereas compound 3 is paramagnetic. Subsequently, the theoretical density functional theory (DFT) and wave function theory-based (DDCI) calculations were carried out to better understand the role of the water molecule as a mediator of the magnetic coupling. The use of localized orbitals allows one to elucidate the role of the H-bonds in generating exchange interactions. Since the exchange-coupling constants are strongly dependent on the mechanisms selectively introduced, the role of the H-bond is demonstrated.