New Pyridine Carboxamide Ligands and their Complexation to Copper(II). X-Ray Crystal Structures of Mono-, Di, Tri- and Tetranuclear Copper Complexes

SL Jain, P Bhattacharyya, HL Milton, Alexandra Martha Zoya Slawin, Joseph Alan Crayston, John Derek Woollins

Research output: Contribution to journalArticlepeer-review

109 Citations (Scopus)

Abstract

Seven new pyridine dicarboxamide ligands H2L1-7 have been synthesised from condensation reactions involving pyridine-2,6-dicarboxylic acid (H(2)dipic), pyridine-2,6-dicarbonyl dichloride or 2,6-diaminopyridine with heterocyclic amine or carboxylic acid precursors. Crystallographic analyses of N,N'-bis(2-pyridyl)pyridine-2,6-dicarboxamide monohydrate (H2L8.H2O), N,N'-bis[2-(2-pyridyl)methyl]pyridine-2,6-dicarboxamide and N,N'-bis[2-(2-pyridyl)ethyl] pyridine-2,6-dicarboxamide monohydrate revealed extensive intramolecular hydrogen bonding interactions. 2,6-Bis(pyrazine-2-carboxamido)pyridine (H2L6) and 2,6-bis(pyridine-2-carboxamido)pyridine (H2L7) reacted with copper(II) acetate monohydrate to give tricopper(II) complexes [Cu-3(L)(2)(mu(2)-OAc)(2)]. X-Ray crystallography confirmed deprotonation of the amidic nitrogen atoms and that the (L-6,L-7)(2-) ligands and acetate anions hold three copper(II) ions in approximately linear fashion. H2L8. Reacted with copper(II) tetrakis(pyridine) perchlorate to give [Cu(L-8)(OH2)](2).2H(2)O, in which (L-8)(2-) was tridentate through the nitrogen atoms of the central pyridine ring and the deprotonated carboxamide groups at one copper centre, with one of the terminal pyridyl rings coordinating to the other copper atom in the dimer. The corresponding reaction using H2L7 gave [Cu-3(L-7)(2)(py)(2)][ClO4](2), which transformed during an attempted recrystallisation from ethanol under aerobic conditions to a tetracopper(II) complex [Cu-4(L-7)(2)(L-7-O)(2)].

Original languageEnglish
Pages (from-to)862-871
Number of pages10
JournalDalton Transactions
Issue number6
DOIs
Publication statusPublished - 2004

Keywords

  • ELECTRONIC-PROPERTIES
  • AMIDE COMPLEXES
  • METAL-COMPLEXES
  • PYRIDINE-2,6-DICARBOXAMIDE
  • CHEMISTRY
  • RECEPTORS
  • CU(II)
  • BOND

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