Project Details Nomenclature for polyhedral boranes and related compounds

Project No.:
Start Date:
01 February 2013
End Date:
19 December 2019


Boron hydrides (and related compounds) have unique structural features and this has resulted in a unique systematic approach for their nomenclature. This has been presented in IUPAC ‘Red Book’ publications on Nomenclature of Inorganic Chemistry, 1990 and 2005. It is now timely to review and update these recommendations in the light of (i) possible ambiguities within the current IUPAC systems, (ii) new developments which were noted but not included in the 2005 publication, and (iii) advances in the chemistry that have taken place since that publication.

The review will be undertaken by leading international experts in the field. The outcome of the review process will be a manuscript updating the existing nomenclature system in this specialized area of Inorganic Chemistry.


The proposer undertook a review of boron hydride nomenclature in March 2012 and presented his findings, in the form of a report and oral presentation, to the Division VIII IUPAC meeting in Lisbon in July 2012. The committee endorsed the idea of reworking the boron chapter in the Red Book, and the proposer agreed to undertake the drafting of a project proposal.

It is anticipated that the working group use the report as a starting point for the updating process. The key points of the report are listed below.

  1. The interplay between ‘stoichiometric’ and ‘structural-descriptor’ nomenclature is currently oversimplified and the use of structural descriptors needs clarification.
  2. The system for indicating the number of H atoms in parentheses in polyhedral species is inconsistent, particularly the case for hydride ligands which are coordinated to a metal.
  3. ‘Adduct’ formation e.g. B5H9(PMe3)2, is a tricky nomenclature problem, which needs detailed consideration.
  4. Terminology associated with of isomeric species and non-deltahedral cluster geometries e.g. isocloso, precloso, which have found their way into the chemical literature needs to be clarified.
  5. The names for polyhedral borate anions, ligand-substituted polyhedral borate anions, and polyhedral cations need a more detailed investigation.
  6. A common development for nomenclature involving boron hydrides, Zintl anions, and transition-metal carbonyl cluster compounds needs to be considered.

Working group members, who are all experts in various aspects of polyhedral chemistry, are more than likely to introduce addition areas of concern which require consideration and updating. This will be thoroughly discussed, and a working plan approved, in the first face-to-face meeting to be held in the summer of 2013.


May 2014 update – A preliminary Technical Report has been drafted and the task group members have been charged with investigating the more challenging aspects of the project. The TG will meet during the Imeboron 15 meeting in Prague (24-28 August 2014) and the TGC will present a poster with highlights of the project.

Aug 2018 update – The doc of the provisional recommendations is available for public comments till 31 Dec 2018 > See prov rec

January 2020 update – The IUPAC recommendations are published in Pure and Applied Chemistry, online Ahead-Of-Print 19 Dec 2019,; in print, PAC 2020 Vol 92, No. 2, pp. 355-381.
Project completed

Page last updated: 26 Feb 2020