Structure of PH4Br

What is the structure of $\ce{PH4Br}$? I would like to know which atom is bonded to which. Are all five atoms directly bonded to phosphorus?




No, not in the solid state. The most recent crystal structure analysis suggests there are nearly ideal tetrahedra of phosphonium cations $\ce{PH4+}$ with bromine anions $\ce{Br-}$ in between bound via H-bonds [1, ICSD#23691]:


[![enter image description here](https://i.stack.imgur.com/w5UJJ.png)](https://i.stack.imgur.com/w5UJJ.png)


### Reference


1. Schroeder, L. W.; Rush, J. J. The Journal of Chemical Physics 1971, 54 (5), 1968–1973. [DOI 10.1063/1.1675127](https://doi.org/10.1063%2F1.1675127).


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