[Methanenitrile1]

I have the task to name five elements that tend to form multiple center-bonds and then briefly go over their structures. Lithium, magnesium, beryllium and aluminum really weren't a problem but now I am stuck with boron.
I know that boron in itself or in the form of boranes forms (3c–2e) bonds and that there are also icosahedrons that are connected over (3c–2e) bonds but I don't know what happens as soon as you add organic compounds to the mix.

According to my prof organoboranes solve their electron deficit with hyperconjugation as opposed to multiple center bonding so is boron just not an answer to the question? Or does boron just do the same as aluminum, aka form dimers?
And well, if boron is not the answer, then what is? I know copper kinda does some tetrameric structures but I am not sure this is the answer my prof wants to hear.