Zwitterionic {Fe(I)Pc(-2)-}·(TMP+) assemblies comprising anionic iron(I) phthalocyanines and coordinating N,N,N'-trimethylpiperazinium cations

Dalton Trans. 2013 Jul 21;42(27):9870-6. doi: 10.1039/c3dt50855b. Epub 2013 May 21.

Abstract

{[Fe(I)Pc(-2)(-)]·(TMP(+))}·0.5C6H14 (1) and {Co(i)Pc(-2)(-)}·(TMP(+)) (2) salts containing iron(I) and cobalt(I) phthalocyanine anions and N,N,N'-trimethylpiperazinium cations (TMP(+)) have been obtained as single crystals. The TMP(+) cations coordinate to the iron(I) centers in 1 by free nitrogen atoms to form a weak N(TMP(+))-Fe bond of 2.568(3) and 2.553(3) Å length at 150 and 105 K, respectively. This is the first zwitterionic assembly containing anions and cations in one neutral coordination {[Fe(I)Pc(-2)(-)]·(TMP(+))} unit. The Fe(I)Pc(-2)(-) anions manifest strongly asymmetric EPR signals in the spectrum of 1 which can be fitted well by four components at 298 K with g1 = 2.1770, g2 = 2.1681, g3 = 2.1425 and g4 = 2.0708. The signal is attributed to the low-spin (S = 1/2) Fe(I) with the d(7) configuration. The EPR spectrum of 1 does not change qualitatively upon slow cooling from 298 down to 4 K. Quenching of the sample for seconds produces a different EPR spectrum at 4 K. This spectrum can be attributed to the frozen metastable state of Fe(I)Pc(-2)(-) which exists only at low temperatures and transfers to the spectrum observed for the slowly cooled sample above 70 K. Salt 2 contains EPR silent cobalt(I) with the d(8) configuration and in this case the TMP(+) cations do not coordinate to the cobalt(I) atoms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cations / chemistry
  • Cobalt / chemistry
  • Crystallography, X-Ray
  • Indoles / chemistry*
  • Iron / chemistry*
  • Isoindoles
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Piperazines / chemistry*

Substances

  • Cations
  • Indoles
  • Isoindoles
  • N,N,N'-trimethylpiperazinium
  • Organometallic Compounds
  • Piperazines
  • Cobalt
  • Iron
  • phthalocyanine