Thermodynamics of Molecular Metal Formation: Metallophthalocyanine and Tetrathiafulvalene Iodides

William B. Euler, Mary E. Melton, Brian M Hoffman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Solid-state electrochemical cells are employed to investigate the formation reaction of several iodinated materials, DIx, where D is a metallophthalocyanine (M(Pc), M = H2, Ni, Co, Cu) or tetrathiafulvalene (TTF). I2 and [(CH3)4N]I3 cells were also studied as controls. The M(Pc)I constitute a set of isostructural and isoionic molecular conductors; in contrast, the TTFIx (x = 0.7, 2, 3) differ in structure, level of oxidation, and the state of the iodine. For none of the DIx studied does the formation reaction of the parent D and molecular iodine have a free energy more favorable than −5.2 kcal/mol. This is so despite the highly favorable lattice stabilization energies, L, that are calculated from appropriate Born-Haber cycles: L ranges from −103 to −117 kcal/mol in the nonintegrally (partially) oxidized materials while L = −164 ± 5 kcal/mol in the integrally oxidized TTFI3. Individual contributions to L, namely the nonbonded, ionic, and mixed-valence, or carrier-delocalization, contributions, are also discussed. The first two of these are large and contribute in different proportions for the M(Pc)I and (TTF)Ix. The third, though small, can be of the same magnitude as or greater than the total free energy of formation.

Original languageEnglish (US)
Pages (from-to)5966-5971
Number of pages6
JournalJournal of the American Chemical Society
Volume104
Issue number22
DOIs
StatePublished - Jan 1 1982

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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