Linear chain compound

Magnus's green salt is an example of a linear chain compound.

In chemistry and materials science, linear chain compounds are materials composed of one-dimensional arrays of metal-metal bonded molecules or ions. Such materials exhibit anisotropic electrical conductivity.

Examples

Many linear chain compounds feature square planar complexes. One example is Rh(acac)(CO)₂, which stack with Rh···Rh distances of about 326 pm. Classic examples include Krogmann's salt and Magnus's green salt. Another example is the partially oxidized derivatives of [Pt(oxalate)₂]²⁻. The otherwise ordinary complex IrBr(CO)₃ gives an electrically conductive derivative upon oxidation, e.g., with bromine to give IrBr_1+x(CO)_3−x, where x ~0.05. Related chlorides have the formulae IrCl_1+x(CO)₃ and K_0.6Ir(CO)₂Cl₂·½H₂O.

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.

File:HUXDEK.png

An Ni₉ EMAC.

File:ACABRH02.png

Portion of the lattice of Dicarbonyl(acetylacetonato)rhodium(I) (Rh(acac)(CO)₂) showing the "stacking" of the individual planar units through Rh···Rh interactions.

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.

Methodology

Some linear chain compounds are produced or fabricated by electrocrystallization. The technique is used to obtain single crystals of low-dimensional electrical conductors.

See also

• platinum pop