J. Appl. Cryst.の発刊に際して

In continuation of our previous brief review of structural concepts of novel supramolecular proton transfer compounds and their metal complexes by Aghabozorg et al. [1], we briefly surveyed the current research in the field of proton transfer compounds supramolecular synthons and their self-assembled metallic complexes from the points of view of Crystal Engineering and Density Functional Theory (DFT) since 2008. Our research groups have recently focused on the proton delivery from acids, which are considered to be suitable proton donors, to amines as proton acceptors. The results were the production of several proton transfer ion pairs possessing some remaining donor sites applied for coordination to metal centers in the preparation of metal-organic compounds. Some of the complexes showed contributions of both cationic and anionic fragments of the starting ion pair, while some others contained only one of these species as ligand. Our review and investigation of compounds revealed that they mainly focused on the concept of supramolecular systems, co-crystallization, stereochemically active lone pairs, coordination polyhedron, mainly on the various interactions involved, including van der Waals, ion pairing, hydrogen bondings, face to face ν-β stackings and edge to face C-Hπ, C-Oπ, N-H3π and SS. These interactions were the most commonly used strategies in the extension of supramolecular structures.

A brief review of structural concepts of novel supramolecular proton transfer compounds and their metal complexes (part II)

Hydrothermal synthesis, experimental and theoretical characterization of a novel cocrystal compound in the 2:1 stoichiometric ratio containing 6-methyluracil and dipicolinic acid.

The reaction of Zn(NO3)2 with pyridine-2,6-dicarboxylic acid (pydcH2) and acridine (acr) in aqueous solution leads to the formation of the title compound, (C13H10N)[Zn(C7H3NO4)(C7H4NO4)]·5H2O or (acrH)[Zn(pydcH)(pydc)]·5H2O. In the title compound, the ZnII atom is coordinated by four O atoms and two N atoms from the tridentate chelating rings of (pydc)2− and (pydcH)− anions. The geometry of the resulting ZnN2O4 coordination can be described as distorted octa­hedral. To balance the charges, one protonated acridine (acrH)+ cation is present. In the crystal structure, extensive O—H⋯O and N—H⋯O hydrogen bonds involving acrH+, the complex anion and uncoordinated water mol­ecules form a three-dimensional network.

https://journals.iucr.org/e/issues/2009/04/00/bq2129/bq2129.pdf

Acridinium (6-carboxy­pyridine-2-carboxyl­ato)(pyridine-2,6-dicarboxyl­ato)zincate(II) penta­hydrate

Three new metal–organic compounds formulated as (H2bda)[Mn(pydc)2]·3H2O (1), (H2bda)[Zn(pydc)2]·3H2O (2), and (H2bda)3[Ce(pydc)3]2·4H2O (3) have been synthesized and structurally characterized by elemental analyses, IR, 1H and 13C NMR spectroscopies, and single crystal X-ray diffraction method. The asymmetric units of 1 and 2 contain three water molecules where in both compounds the corresponding metallic center is six-coordinated by two N and four O atoms as a distorted octahedral. The asymmetric unit of 3 contains four water molecules and the Ce(III) atom is nine-coordinated by three N and six O atoms in a distorted tricapped trigonal prism that the N atoms capping the faces. In the crystalline network of these three coordination compounds, hydrogen bonds, π–π stacking, and ion pairing play basic roles in the formation of supramolecular structures, in which they seem to be effective factor in the stabilization of the structure. The protonation constants of bda and pydcH2 and the (H2bda)(pydc) proton transfer equilibrium constants, the stoichiometry and stability of complexes of above mentioned ion pair with Mn2+, Ni2+, Cu2+, Zn2+, Cd2+, and Ce3+ metal ions in aqueous solution were investigated by potentiometric pH titration method. The stoichiometry of the most complexed species in solution was compared with corresponding crystalline complexes in the solid state. The syntheses, X-ray crystal structures, and solution studies of three new coordination compounds based upon Mn(II), Zn(II), and Ce(III) atoms together with solution studies of previously synthesized coordination compounds by our research groups containing Ni(II), Cu(II), and Cd(II) atoms have been reported here, for the first time.

Syntheses, crystal, and molecular structures of Mn(II), Zn(II), and Ce(III) compounds and solution studies of Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ce(III) compounds obtained from a suitable proton transfer compound containing bda and pydcH2 (bda = butane-1,4-diamine; pydcH2 = pyridine-2,6-dicarboxylic acid)

Novel metal organic frameworks including {(pipzH2)[Mn(py-2,3-dc)2]·7.75H2O}n, 1, {(pipzH2)[Zn(py-2,3-dc)2]·4H2O}n, 2, [Cd(py-2,3-dc)(H2O)3]n, 3 and {(pipzH2)[Hg4Cl10]}n, 4, in which pipz is piperazine and py-2,3-dcH2 is pyridine-2,3-dicarboxylic acid were synthesized applying a proton transfer ion pair i.e. (pipzH2)(py-2,3-dcH)2 and corresponding metallic salts and studied by IR, 1H NMR, 13C NMR spectroscopy and single crystal X-ray diffractometry. The space group of compounds 1 and 4 are P21/c and C2/c of monoclinic system, respectively. The crystal dimensions are a = 20.108(2) A, b = 19.910(2) A, c = 12.997(1) A, β = 94.354(2)° for 1 and a = 15.940(1) A, b = 11.2690(9) A, c = 11.1307(9) A, β = 90.685(2)° for 4. The crystal structures of 2 and 3 have been reported previously. However, their solution studies are discussed here. The compounds had all polymeric structures. Although ZnII, CdII and HgII were elements of the same group, their behavior against the ion pair was essentially different. Various supramolecular interactions mainly hydrogen bonds of the type O-H⋯O, N-H⋯O, C-H⋯O, N-H…Cl and C-H⋯Cl were observed in the structures. There was an unusual and huge water cluster in the structure of compound 1. The solution states of compounds 1–4 were studied and reported. The protonation constants of pipz and py-2,3-dc, the py-2,3-dc/pipz proton transfer equilibrium constants and stoichiometry and stability of the system with Mn2+, Zn2+, Cd2+ and Hg2+ ions in aqueous solution were investigated by potentiometric pH titrations.

Synthesis and Crystal Structure of Mn(II) and Hg(II) Compounds and Solution Studies of Mn(II), Zn(II), Cd(II) and Hg(II) Compounds Based on Piperazinediium Pyridine-2,3-dicarboxylate

The title compound, (C3H7N6)2[Co(H2O)6][Co(C7H3NO4)2]2·4H2O, or (tataH)2[Co(H2O)6][Co(pydc)2]2·4H2O (where tata is 2,4,6-triamino-1,3,5-triazine and pydc is pyridine-2,6-dicarboxylic acid), was obtained by reaction of Co(NO3)2·6H2O with the proton-transfer compound (tataH)2(pydc) in aqueous solution. The [Co(pydc)2]2− anion is a six-coordinate CoII complex with a distorted octa­hedral coordination geometry. The structure also contains hexa­aqua­cobalt(II) cations (site symmetry \overline{1}), (tataH)+ cations and uncoordinated water mol­ecules. The two(pydc)2− ligands in each [Co(pydc)2]2− anion are almost perpendicular to each other [dihedral angle between their mean planes = 82.3 (1)°]. There is extensive O—H⋯O, N—H⋯N, O—H⋯N and C—H⋯O hydrogen bonding in the structure, as well as π–π stacking between (pydc)2− ligands with an inter­planar distance of 3.484 (15) A.

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Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hexa­aqua­cobalt(II) bis­[bis­(pyridine-2,6-dicarboxyl­ato)cobaltate(II)] tetra­hydrate

The title compound, (C3H7N6)2[Zr(C7H3NO4)3]·4H2O or (tataH)2[Zr(pydc)3]·4H2O (tata is 2,4,6-triamino-1,3,5-triazine and pydcH2 is pyridine-2,6-dicarboxylic acid), was obtained by reaction between pydcH2, tata and zirconyl chloride octa­hydrate in aqueous solution. In the structure, the ZrIV atom is nine-coordinated by three (pydc)2− groups, resulting in an anionic complex which is balanced by two (tataH)+ cations. One of the NH2 groups shows positional disorder, with site occupation factors of 0.60 and 0.40. There are four uncoordinated water mol­ecules (one of which is disordered with occupation factors of 0.70 and 0.30) in the crystal structure. Several inter­molecular inter­actions, including O—H⋯O, O—H⋯N, N—H⋯O, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds, a C—O⋯π inter­action [O⋯Cg 3.89, C⋯Cg 4.068 (3) A; C—O⋯Cg 89° where Cg is the centroid of the triamine ring], and π–π stacking [with centroid–centroid distances of 3.694 (2) and 3.802 (2) A] are also present.

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Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)-zirconate(IV) tetra-hydrate.

The title compound, (C3H7N6)4[Ca(C7H3NO4)3]·6H2O or (tataH)4[Ca(pydc)3]·6H2O (where tata is 2,4,6-triamino-1,3,5-triazine and pydcH2 is pyridine-2,6-dicarboxylic acid), was obtained by reaction of Ca(NO3)2·4H2O with the proton-transfer compound (tataH)2(pydc) in aqueous solution. The [Ca(pydc)3]4− anion has twofold crystallographic symmetry. It is a nine-coordinate CaII complex with a distorted tricapped trigonal-prismatic coordination geometry. The structure also contains four tataH+ cations and six uncoordinated water mol­ecules. There are extensive O—H⋯O, O—H⋯N, N—H⋯O, N—H⋯N and C—H⋯O hydrogen bonds in the crystal structure.

/pdf/tetra-kis-2-4-6-triamino-1-3-5-triazin-1-ium-tris-pyridine-2-3vttpy3ip1.pdf

Shirin Daneshvar

Papers

Synthesis and Crystal Structure of Mn(II) and Hg(II) Compounds and Solution Studies of Mn(II), Zn(II), Cd(II) and Hg(II) Compounds Based on Piperazinediium Pyridine-2,3-dicarboxylate

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hexaaquacobalt(II) bis[bis(pyridine-2,6-dicarboxylato)cobaltate(II)] tetrahydrate

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)-zirconate(IV) tetra-hydrate.

Tetra-kis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)calcate(II) hexa-hydrate.

Shirin Daneshvar

Papers

Synthesis and Crystal Structure of Mn(II) and Hg(II) Compounds and Solution Studies of Mn(II), Zn(II), Cd(II) and Hg(II) Compounds Based on Piperazinediium Pyridine-2,3-dicarboxylate

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hexa­aqua­cobalt(II) bis­[bis­(pyridine-2,6-dicarboxyl­ato)cobaltate(II)] tetra­hydrate

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)-zirconate(IV) tetra-hydrate.

Tetra-kis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)calcate(II) hexa-hydrate.

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hexaaquacobalt(II) bis[bis(pyridine-2,6-dicarboxylato)cobaltate(II)] tetrahydrate