Strange 1H-NMR signals/signal ratio

[Fedorov et al.](http://dx.doi.org/10.1023/B:RUCB.0000030813.05424.1f) assign the $^1$H-NMR ($\ce{CDCl3}$) chemical shifts of the $\ce{CH2}$ group in 2-(bromomethyl)phenylboronic acid


![2-(bromomethyl)phenylboronic acid](https://i.stack.imgur.com/Gr1rj.png)


to three singlets at $4.75$, $5.09$ and $5.15~\ce{ppm}$ in a ratio of $3:3:14$.


Can someone explain their reasoning?




The paper specifically addresses this issue and ascribes it to the tendency for boronic acids to exist as solvent and concentration dependent oligomers:



> 
> The dependence of the intensity ratio for these signals and the
>  chemical shifts in the 1H NMR spectra on the concentration of the
>  samples under study as well as on the nature of the solvents used
>  indicates that anhydrides of boronic acids with different degrees of
>  oligomerization can exist along with monomeric forms of these
>  derivatives (ArB(OH)2) in solutions of substituted arylboronic acids.
>  The conclusions about the existence of oligomeric forms of boronic
>  acids and the absence of byproducts in the compounds isolated are
>  supported by the results published earlier.
> 
> 
> 


This type of equilibrium can be expressed like:
![enter image description here](https://i.stack.imgur.com/hQ2IU.png)


Higher order oligomers are also possible.


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