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
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. 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_{0.6}Ir(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.





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.