Sterically Hindered, Saddle-Shaped Complexes of Palladium(II) and Platinum(II) and Their Reaction with Iodine

Alan John Jircitano, Mark D. Timken, John R. Ferraro, Kristin Bowman Mertes

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The synthesis and characterization of I2 reaction products of palladium(ll) and platinum(II) with the tetraaza ma crocycle tetrabenzo[b, f, j, n][l, 5, 9, 13] tetraazacyclohexadecine (TAAB) from [M(TAAB)][BF4]2 are described. X-ray structural results for [Pd(TAAB)][BF4]2 show the complex to crystallize in the monoclinic space group P21/c with unit cell dimensions a = 16.927 (6) A, b = 1 1.757 (7) A, c = 15.559 (4) A, and ² = 118.87 (2)°. The immediate coordination sphere of the palladium consists of the four nitrogens situated on a saddle-shaped surface with the palladium located essentially in the center. The ligand system is decidedly saddle shaped, with the benzo groups forming cavities 2.70 A deep above and below the PdN4 surface. In the presence of I2 these complexes react to form a complex with the stoichiometry [M(TAAB)] [I3]2, 7. The presence of I3 - and absence of I2 were confirmed by both far-infrared and Raman spectroscopy. Mid-infrared and EPR evidence substantiates that ligand oxidation has not occurred. Electrical conductivity measurements using dc two-probe techniques indicate an unusual pressure dependence, whereby up to a 1000-fold increase in conductivity at up to 10 kbar pressure is noted. Single-crystal conductivity measurements for [Pt(TAAB)] [13)2.7 indicate conductivities on the order of the partially oxidized bisdioximates (10-4 Ω-1 cm-1 while the palladium analogue is considerably less (10-7 cm-1).

Original languageEnglish (US)
Pages (from-to)7661-7667
Number of pages7
JournalJournal of the American Chemical Society
Issue number26
StatePublished - Feb 1 1979

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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