Mono- and bidentate imidates of five-coordinate nickel(II) with macrocyclic ligands: spectroscopic and photophysical properties

Dalton Trans. 2010 Jun 28;39(24):5728-36. doi: 10.1039/c0dt00036a. Epub 2010 May 21.

Abstract

The hydroxo-complexes [Ni(2)(mcN(3))(2)(mu-OH)](2)(PF(6))(2)] [mcN(3) = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me(3)-mcN(3)) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me(4)-mcN(3))] react with imides (Him) in 1 : 2 (succinimide, glutarimide, saccharine and 1,8-naphthalimide) or 1 : 1 (pyromellitic diimide) molar ratio, leading to the formation of the imidate complexes: [Ni(mcN(3))(H(2)O)(Im)](+) (Im = succi, gluti, sac), [Ni(mcN(3))(naphthi)](+) and [Ni(mcN(3))(H(2)O)](2)(mu-pyrdi)](2+). The single crystal structures of [Ni(Me(3)-mcN(3))(H(2)O)(sac)](PF(6)) (3a) and [Ni(Me(4)-mcN(3))(H(2)O)(sac)](sac) (3b) show that, in 3a, sac exhibits a N-monodentate coordination mode, while in 3b the coordination is through oxygen. X-Ray structure of [Ni(Me(4)-mcN(3))(naphthi)](PF(6)) (4b) shows N,O-bonded 1,8-naphthalimidate ligand. The VT (1)H NMR study, carried out on this complex, suggests that the rotation around the Ni-N bond is hindered by ca. 11.6 kcal mol(-1). These species exhibit blue luminescence which arises from a mixed MLCT and LC excited state, and these properties may be useful for structural predictions in the solid state of complexes for which crystal structures have not been established.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coordination Complexes / chemical synthesis
  • Coordination Complexes / chemistry*
  • Crystallography, X-Ray
  • Imidoesters / chemistry*
  • Ligands
  • Macrocyclic Compounds / chemistry*
  • Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Nickel / chemistry*
  • Spectrometry, Fluorescence

Substances

  • Coordination Complexes
  • Imidoesters
  • Ligands
  • Macrocyclic Compounds
  • pyromellitic diimide
  • Nickel