page_title: Linear chain compound
section_title: Examples
hierarchical_section_title: Linear chain compound / Examples
caption_attribution_description: English: portion of the lattice of Rh(acac)(CO)2 showing the M-M "stacking"
context_page_description: Linear chain compounds are materials composed of one-dimensional arrays of metal-metal bonded molecules or ions. Such materials exhibit anisotropic electrical conductivity.
context_section_description: Most examples are composed of square planar complexes. Thus, upon crystallization, molecules of Rh(acac)(CO)₂ stack with Rh---Rh distances of about 326 pm. Classic examples include Krogmann's salt and Magnus's green salt.  Other examples include the partially oxidized derivatives of [Pt(oxalate)₂]²⁻. The otherwise ordinary complex IrBr(CO)₃ gives an electrically conductive derivative upon oxidation.  Such semiconducting materials are eniched in bromine, i.e. IrBr₁₊ₓ(CO)₃₋ₓ, where x ~0.05. 
  In contrast to linear chain compounds, extended metal atom chains (EMACs) are molecules or ions that consist of a finite, often short, linear strings of metal atoms, surrounded by organic ligands.
  One group of platinum chains is based on alternating cations and anions of [Pt(CNR)₄]²⁺ (R = iPr, c-C₁₂H₂₃, p-(C₂H₅)C₆H₄) and [Pt(CN)₄]²⁻.  These may be able to be used as vapochromic sensor materials, or materials which change color when exposed to different vapors.
  Linear chains of Pd-Pd bonds protected by a “π-electron sheath are known.
  Not only do these olefin-stabilized metal chains constitute a significant contribution to the field of organometallic chemistry, both the complex's metal atom structures and the olefin ligands themselves can conduct a current.
caption: Portion of the lattice of Rh(acac)(CO)2 showing the "stacking" of the individual planar units through Rh---Rh interactions.
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