Synthesis and spectroscopic characterization of five-coordinate complexes of Ni<sup>2+</sup> based on N<inf>3</inf>-macrocycles and salicylaldiminates. Crystal structure of [Ni(9-Me-N<inf>3</inf>-mc)(OC<inf>6</inf>H<inf>4</inf>CH=NC<inf>6</inf>H <inf>5</inf>-o)](ClO<inf>4</inf>) (9-Me-N<inf>3</inf>-mc=2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene)

M. Dolores Santana, Antonio Rufete, Gregorio Sánchez, Gabriel García, Gregorio López, Jaume Casabó, Elíes Molins, Carles Miravitlles

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11 Citations (Scopus)

Abstract

Five-coordinate nickel(II) complexes of the type [Ni(N3-macrocycle)(OC6H4CH=NR-o)]+ (N3-macrocycle=2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene, N3-mc, or its 9-methyl derivative, 9-Me-N3-mc) have been prepared by reaction between [{Ni(N3-macrocycle)(μ-OH)}2]+ and the appropriate arylsalicylaldimine. An X-ray diffraction study carried out with the complex [Ni(9-Me-N3-mc)(OC6H4CH=NC6H 5-o)](ClO4) has established that the Ni atom presents a square pyramidal coordination and is displaced 0.30 Å out of the basal plane towards the apical N1 atom (a=8.552(2), b=33.398(3), c=9.630(3) Å, β=91.67(1)°, monoclinic, space group P21/a, V=2749(1) Å3, Z=4, Dcalc=1.40 g cm-3, R=0.058, Rw=0.066). These paramagnetic species have been studied by 1H NMR. The characteristic pattern of N3-mc and 9-Me-N3-mc has been established and the specific assigment of salicylaldimine resonances has been achieved by NOE measurements. The solution electronic spectra of the complexes are also suggestive of five-coordinate geometry in solution.
Original languageEnglish
Pages (from-to)21-27
JournalInorganica Chimica Acta
Volume255
Issue number1
Publication statusPublished - 1 Feb 1997

Keywords

  • Crystal structures
  • Macrocycle complexes
  • Nickel complexes
  • Pentacoordinate complexes

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