The reaction of 2-(2H-tetrazol-5-yl)pyridine (L1) with 1,6-dibromohexane results in formation of the isomers 2-(6′′-bromohexyl-(1-tetrazol-5-yl)pyridine (L2) and 2-(6′′-bromohexyl-(2-tetrazol-5-yl)pyridine (L3 compounds. X-ray crystal structures were obtained for complexes 1-5. In each complex, ligands L2 and L3 coordinate to the metal centre through the pyridyl N atom and the 1-N site of the tetrazole ring, and the pyridyl-tetrazole ligand remains planar in all cases except 3. Complexes 1 and 2 comprise a central Cu 2 Cl 2 dimeric core with Cu(II) in an essentially square-pyramidal coordination environment. Complexes 3 and 4 contain Co(II) in a distorted octahedral coordination environment.In 3, the pyridyl and tetrazole rings of L2 are twisted with respect to each other and the complex adopts a puckered conformation in its equatorial plane. Complex 5 contains water molecules coordinated to Fe(II) in the axial sites, which form hydrogen bonds to the perchlorate counter anions.3
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AbstractThe coordination of pyridyl-tetrazole derivatives containing ester substituents, at either the N-1 or N-2 position of the tetrazole ring, with copper(II) chloride results in the formation of either 1:1 or 1:2 copper to ligand complexes, depending on the ligand. However, when the ester functionality is changed to a carboxylate group, the resulting complexation reactions yield metal-organic frameworks. The resulting structures vary dramatically in pore size, depending on both reaction solvents and position of carboxylate group on the tetrazole ring.Despite the presence of sodium cations in the reaction mixtures, no sodium incorporation was ever observed in any of the complexes. This report represents the first attempts at producing copper(II) complexes of the N-1 and N-2 carboxylate derivative of this ligand.
a b s t r a c tThe reaction of 2-(2H-tetrazol-5-yl)pyridine (L1) with 1,n-dibromoalkane (n = 3, 4, 6 or 8) results in the formation of the isomers 2-(n 00 -bromoalkyl-(1-tetrazol-5-yl)pyridine (L2A-D) and 2-(n 00 -bromoalkyl-(2-tetrazol-5-yl)pyridine (L3A-D). The reaction of L1 with 1-bromoalkanes also resulted in the formation of isomeric materials, namely 2-(n 00 -alkyl-(1-tetrazol-5-yl)pyridine (L4A-C) and 2-(n 00 -alkyl-(2-tetrazol-5-yl)pyridine (L5A-C). Complexation reactions of these ligands with the transition metal salts CuCl 2 Á2H 2-O, Co(NCS) 2 , NiCl 2 Á2H 2 O and ZnCl 2 were carried out in methanol and resulted in complexes containing a 1:1 metal:ligand stoichiometry except in the cases of the cobalt complexes where a 1:2 metal:ligand stoichiometry was obtained. The 1 H NMR spectra of the zinc complexes showed that the ligands containing the pendant arm in the 2-N position of the tetrazole ring bind the zinc ion more strongly than those containing the pendant arm in the 1-N position. The X-ray structures of two cobalt salts, Co(L5A) 2 (NCS) 2 and Co(L5C) 2 (NCS) 2 , are also discussed.
Three novel bis-tetrazole ligands (1-3) containing carboxylate functional groups on the tetrazole rings and a rigid pyrazine linker unit, for the construction of coordination polymers when coordinated to copper(II) ions, were synthesised and structurally characterised. The use of pyrazine as a rigid linker between the two tetrazole units was expected to increase the dimensionality of the solid phase polymeric network of the resulting copper(II)-containing compounds. X-ray structures of the ligands revealed the effect of the substitution position on the tetrazole ring of the ester/ carboxylate groups. Higher solid phase dimensionality was successfully achieved as shown by the layered two-dimensional (2-D) coordination structure being formed when the pyrazine bis-tetrazole systems were reacted with copper(II) chloride, although not in the expected manner. There was no interaction between the pyrazine nitrogen atoms and the metal ion. Computational studies showed that this was probably due to the geometry, required by the copper ion, to be involved in the close packing between the layers. The 2-D coordination polymer based on the asymmetric substituted pyrazine bis-tetrazole, [Cu(4)(H 2 O)](H 2 O) 2 , was further connected into a three-dimensional (3-D) coordination network through hydrogen bonding between H 2 O molecules. These H 2 O molecules were connected as a unique 1-D chain throughout the structure.Three novel bis-tetrazole ligands (1-3) containing carboxylate functional groups on the tetrazole rings and a rigid pyrazine linker unit, for the construction of coordination polymers when coordinated to copper(II) ions, were synthesised and structurally characterised.
is the new product launch site for the global Pfizer network, but as well as new products, the site manufactures an array of both on-and off-patent active pharmaceutical ingredients (APIs). Chemistry is at the forefront of the site, and the Chemistry Centre of Excellence (COE) within Ringaskiddy hosts a wealth of experience and knowledge, with a strong female representation in both process and technical chemist roles. There is a continual focus on process robustness across the site. Green Belt (GB) projects focus on resolving and eliminating process deviations using Six Sigma tools by a cross-functional team. This article will focus on three GB projects on two different APIs manufactured at Ringaskiddy which were led by female process chemists.
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