Mulyana, Yanyan published the artcileNew cobalt(II) and zinc(II) coordination frameworks incorporating a pyridyl-pyrazole ditopic ligand, Category: pyrazoles-derivatives, the publication is Dalton Transactions (2005), 1598-1601, database is CAplus and MEDLINE.
The metal-directed assembly of new mol. frameworks incorporating 4-(4-pyridyl)pyrazole (HL), containing non-linear coordination vectors, is presented. Three metallo-arrays of types [Co(LH2)2(NO3)4], [Co(LH2)2(H2O)4][NO3]4·H2O and [Zn2(L)2Cl2]·2EtOH. The cobalt(II) in [Co(LH2)2(NO3)4] displays distorted octahedral geometry with the two protonated pyridylpyrazole ligands coordinated through their pyrazole nitrogen atoms in a trans-orientation and the remaining four coordination sites occupied by nitrate anions. Two internal hydrogen bonds occur between each pyrazole NH and the oxygens of adjacent coordinated nitrato ligands. Short intermol. hydrogen bonds also occur between the two pyridinium hydrogens and bound nitrate ligands on different mols. to yield a two-dimensional hydrogen-bonded array. Two of these arrays interpenetrate to form an extended two dimensional layer. The two-dimensional layers stack throughout the crystal structure. A second product of type [Co(LH2)2(H2O)4][NO3]4·H2O exists as two crystallog. independent forms that are chem. similar. In each form, the two protonated pyridylpyrazole ligands occupy trans positions about the cobalt with the remaining four coordination sites being filled by water mols. to yield a distorted octahedral coordination geometry. Intramol. hydrogen-bonding is observed between the two non-coordinated pyrazoyl nitrogen atoms and bound water oxygen atoms. The third complex, [Zn2(L)2Cl2]·2EtOH, contains dimer units consisting of two zinc(II) ions bridged by two pyrazoylate groups in which the coordination geometry of each zinc approximates a tetrahedron. Each zinc is bound to two deprotonated pyridylpyrazolato ligands, one pyridyl group (from a different dimeric unit) and one chloro ligand. Each pyridyl nitrogen thus connects each of these zinc dimers to an adjacent dimer unit, forming a three-dimensional network containing small voids. The latter are occupied by ethanol mols. which form hydrogen bonds to the chloro ligands.
Dalton Transactions published new progress about 19959-71-8. 19959-71-8 belongs to pyrazoles-derivatives, auxiliary class Pyrazole,Pyridine, name is 4-(1H-Pyrazol-4-yl)pyridine, and the molecular formula is C8H7N3, Category: pyrazoles-derivatives.
Referemce:
https://en.wikipedia.org/wiki/Pyrazole,
Pyrazoles – an overview | ScienceDirect Topics