Counterion effects in Pd polyselenides: Evolution from molecular to three-dimensional framework structures

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Abstract

Several palladium polyselenides were prepared by the reactions of Pd2+ ions with Se(x)2- (4 < x < 6) ligands in the presence of various cations. {(CH3)N(CH2CH2)3N}2[Pd(Se6)2] (I) was prepared by the methanothermal reaction of K2PdCl4, K2Se4, and {(CH3)3N(CH2CH2)N(CH3)3}I2 in a 1:3:2 molar ratio at 110 °C. Compound I crystallizes in the space group P21/c with a = 9.403(3) Å, b = 15.050(5) Å, c = 10.807(4) Å, β = 91.73(3)°, and V = 1528.7(9) Å3. (H3NCH2CH2NH2)2[Pd(Se5)2] (II) was prepared by the methanothermal reaction of PdCl2, Na2Se4, and (H3NCH2CH2NH3)Cl2 in a 1:3:1 molar ratio at 80 °C. Compound II crystallizes in the space group P21/n with a = 9.412(3) Å, b = 8.671(3) Å, c = 12.666(3) Å, β = 98.38(2)°, and V = 1023(1) Å3. The anions in [Pd(Se5)2]2- in II and [Pd(Se6)2]2- in I are polymeric and possess layered structures. The organic cations are located between the layers. K2(H3NCH2CH2NH3)2[Pd(Se4)2·2Se4] (III) was prepared by the methanothermal reaction of PdCl2, K2Se4, and (H3NCH2CH2NH3)Cl2 in a 1:3:1 molar ratio at 80 °C. Compound III crystallizes in the space group I212121 with a = 12.587(9) Å, b = 15.271(5) Å, c = 15.404(9) Å, and V = 2961(5) Å3. The [Pd(Se4)2·2Se4]6- anion in III is composed of a [Pd(Se4)2]2- three-dimensional adamantane-like framework with large cavities that are filled with the counterions and with uncoordinated Se42- ligands. K6[Pd(Se5)4] (IV) was prepared by the methanothermal reaction of K2PdCl4 and K2Se5 in a 1:6 molar ratio at 80 °C. The black polyhedral crystals of IV are slightly soluble in water. Compound IV crystallizes in the space group Pbcn with a = 12.427(4) Å, b = 13.777(9) Å, c = 19.190(9) Å, and V = 3285(5) Å3. The [Pd(Se5)4]6- anion is molecular and one of the most Se-rich metal polyselenides known. It has a palladium center with four dangling Se52- ligands around it. Being a molecular fragment, it can be regarded as a building block for extended [Pd(Se(n))2]2- frameworks. Optical spectroscopic and thermal gravimetric analysis data for the compounds are reported.

Original languageEnglish
Pages (from-to)8124-8135
Number of pages12
JournalJournal of the American Chemical Society
Volume120
Issue number32
DOIs
Publication statusPublished - Aug 19 1998

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ASJC Scopus subject areas

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

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