High nuclearity Ni(II) cages from hydroxamate ligands

Cecelia McDonald, Sergio Sanz, Euan K. Brechin, Mukesh Kumar Singh, Gopalan Rajaraman, Declan Gaynor*, Leigh F. Jones

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The synthesis, structural and magnetic characterisation of a family of Ni(II) cages built from hydroxamate ligands is presented. Two pentanuclear 12-MCNi(II)-4 metallacrowns [Ni-5(L-1)(4)(MeOH)(4)](ClO4)(2)center dot 2MeOH (1) and [Ni-5(L-1)(4)(py)(5)](ClO4)(2)center dot H2O (2) (where L1H2 = 2-(dimethylamino)phenylhydroxamic acid) share analogous, near-planar {Ni-5(L-1)(4)}(2+) cores, but differ in the number and nature of the ligands located at the axial Ni-(II) sites; the addition of pyridine converting square planar Ni-(II) ions to square-based pyramidal and octahedral Ni-(II) ions, introducing extra paramagnetic metal centres which 'switch on' additional magnetic superexchange pathways. Subtle variations in the reaction scheme used to produce complexes 1 and 2 result in both a change of topology and an increase in nuclearity, through isolation of the hepta- and nonametallic complexes [Ni-7(L1H)(8)(L-1)(2)(H2O)(6)](SO4)center dot 15H(2)O (3), [Ni-9(mu-H2O)(2)(L-2)(6)(L2H)(4)(H2O)(2)](SO4)center dot 29H(2)O (4) and [Ni-9(mu-H2O)(2)(L-2)(6)(L2H)(4)(H2O)(2)](ClO4)(2)center dot 2MeOH center dot 18H(2)O (5) (where L2H2 = 2-(amino) phenylhydroxamic acid). Complementary dc magnetic susceptibility studies and DFT analysis indicate dominant antiferromagnetic exchange interactions in 1, 2, 4 and 5, but competing ferro- and antiferromagnetic exchange in 3.

Original languageEnglish
Pages (from-to)38182-38191
Number of pages10
JournalRSC Advances
Volume4
Issue number72
Early online date13 Aug 2014
DOIs
Publication statusPublished - Sep 2014

Keywords

  • GAUSSIAN-BASIS SETS
  • MAGNETIC-PROPERTIES
  • COORDINATION CHEMISTRY
  • DINICKEL(II) COMPLEXES
  • SPIN-EXCHANGE
  • ATOMS LI
  • NICKEL
  • INHIBITION
  • ACIDS
  • METALLACROWNS

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