The review focuses on the development of hybrid organic–inorganic π conjugated, silane, siloxane and coordination polymers containing boron clusters, which have received considerable academic and technological interest due to the combination of the electronic, optical and thermal properties of traditional inorganic materials with desirable properties of organic plastics, including mechanical flexibility and low production costs.

Boranes, heteroboranes and metallacarboranes, all named as boron clusters, offer an alternative to typical organic molecules or organic molecular materials. Carbon and boron share the important property of self-catenation thus these elements can produce individually large and sophisticated molecules. Boron clusters and organic molecules display electronic, physical, chemical and geometrical characteristics manifestly different. These differences highlight the complementarity of organic molecules and boron clusters, and therefore the feasibility or necessity to produce hybrid molecules incorporating both types of fragments. To join these two types of fragments, or alternatively these two types of molecular compounds, tools are needed. In this review the current methods of producing boron clusters with carbon, B–C, nitrogen, B–N, phosphorus, B–P and sulphur bonds, B–S, are indicated. As there are many existing borane clusters of different sizes, heteroboranes and metallacarboranes, the revision of methods to generate the B–C, B–P, B–S, and B–N bonds has been restricted to the most widely used boron clusters; [B₁₂H₁₂]²⁻, dianionic and an example of a borane, 1,2-C₂B₁₀H₁₂, neutral and an example of a heteroborane, and [Co(C₂B₉H₁₁)₂]⁻, monoanionic and an example of a metallacarborane.

This tutorial review will deal with the study of metallacarboranes and their interactions with other molecules from a theoretical point of view. This contribution is devoted to guide experimental chemists through calculations that some years ago were reserved to theoretical specialists. The widespread availability of fast computers enables nowadays studies of complex compounds (e.g. metallacarboranes) from different perspectives including simulation of NMR, infrared or Raman spectra and calculation of other properties such as atomic charges or inter-/intramolecular interactions. The insights gained on the basis of theoretical calculations are crucial for either finding novel or improving existing applications of metallacarboranes. For example, in the case of enzyme inhibitors, the interactions of the metallacarboranes with the surrounding protein and how the interaction affects the efficiency are difficult problems to study experimentally. The use of theoretical tools can provide a detailed understanding of the physico-chemical basis of the interactions and thus offers a chance to control the overall process.

New applications in which the carborane and metallacarborane species play a crucial role have been recently developed. In these applications, clusters display many particular characteristics that do not find parallel in their organic counterparts. The o-carborane can modulate the C···C distances depending on the substituents bonded to the cluster carbon atom and can lead to the formation of uncommon halogenophosphane charge-transfer “spoke ” complexes with iodine due to their electron-withdrawing capacity. Besides, metallacarboranes have been used as doping agents in organic conducting polymers and as catalysts in Kharasch reactions.