Different types of compounds. Part III

Cluster compounds
Decaborane is a powerfully toxic cluster compound of boron. Iron-sulfur clusters are central components of iron-sulfur proteins, essential for human metabolism.
Clusters can be found in all classes of chemical compounds. According to the commonly accepted definition, a cluster consists minimally of a triangular set of atoms that are directly bonded to each other. But metal-metal bonded dimetallic complexes are highly relevant to the area. Clusters occur in "pure" inorganic systems, organometallic chemistry, main group chemistry, and bioinorganic chemistry. The distinction between very large clusters and bulk solids is increasingly blurred. This interface is the chemical basis of nanoscience or nanotechnology and specifically arise from the study of quantum size effects in cadmium selenide clusters. Thus, large clusters can be described as an array of bound atoms intermediate in character between a molecule and a solid.
Examples: Fe3(CO)12, B10H14, [Mo6Cl14]2−, 4Fe-4S
Bioinorganic compounds
The octahedral cobalt centre of Vitamin B12. These compounds occur (by definition) in nature, but the subfield includes anthropogenic species, such as pollutants and drugs, e.g. Cisplatin. The field includes many compounds, e.g. the phosphates in DNA, but also metal complexes containing ligands that range from biological macromolecules, commonly peptides, to ill-defined species such as humic acid, and to water (e.g. coordinated to gadolinium complexes employed for MRI).
• Examples: hemoglobin, methylmercury, carboxypeptidase
Solid state compounds
YBa2Cu3O7, or YBCO, is a high temperature superconductor able to levitate above a magnet when colder than its critical temperature of about 90 K (−183°C).
This important area focuses on structure, bonding, and the physical properties of materials. In practice, solid state inorganic chemistry uses techniques such as crystallography to gain an understanding of the properties that result from collective interactions between the subunits of the solid. Included in solid state chemistry are metals and their alloys or intermetallic derivatives. Related fields are condensed matter physics, mineralogy, and materials science.
• Examples: silicon chips, zeolites, YBa2Cu3O7