Iridium: bond enthalpies in gaseous diatomic species

The bond energy in the gaseous diatomic species IrIr is (no data) kJ mol-1.

The following values refer to neutral heterodiatomic molecules in the gas phase. These numbers may well differ considerably from, say, single bond energies in a solid. All values are given in kJ mol-1.

Table of diatomic IrX bond enthalpies. All values are quoted in kJ mol-1. Each formula in the table (IrO, IrF, and so on) is a link - select these to see visual periodicity representations for bond enthalpies involving iridium to elements of your choice.

Period 1

IrH             IrHe

Period 2

IrLi IrBe IrB IrC IrN IrO IrF IrNe
    514.2 ±17.2 632 ±4   414.6 ±42.3    

Period 3

IrNa IrMg IrAl IrSi IrP IrS IrCl IrAr
      462.8 ±20.9        

Period 4

IrK IrCa IrGa IrGe IrAs IrSe IrBr IrKr

Period 5

IrRb IrSr IrIn IrSn IrSb IrTe IrI IrXe

Period 6

IrCs IrBa IrTl IrPb IrBi IrPo IrAt IrRn

Period 7

IrFr IrRa            


I am grateful to Professor J.A. Kerr (University of Birmingham, UK) for the provision of the bond strengths of diatomic molecules data.

The values given here are at 298 K. All values are quoted in kJ mol-1. Generally, these data were obtained by spectroscopic or mass spectrometric means. You should consult reference 1 for further details. A note of caution: the strength of, say, the C-H bond in the gaseous diatomic species CH (not an isolable species) is not necessarily, the same as the strength of a C-H bond in, say, methane.

The strongest bond for a diatomic species is that of carbon monoxide, CO (1076.5 ± 0.4 kJ mol-1). The strongest bond for a homonuclear diatomic species is that of dinitrogen, N2 (945.33 ± 0.59 kJ mol-1).


  1. J.A. Kerr in CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, D.R. Lide, (ed.), CRC Press, Boca Raton, Florida, USA, 81st edition, 2000.

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iridium atomic number