It's known that the elements in IVA all have valence +2 and +4. I also know there exists $\ce{GeCl2}$ and $\ce{SnCl2}$. So my question is does $\ce{SiCl2}$, or even $\ce{CCl2}$ exist? If yes, what about their molecular structure?
In addition, what makes +2 valence in $\ce{Ge}, \ce{Sn}$ more stable?
Via Wikipedia, $\ce{CCl2}$, where carbon is in the +2 oxidation state, does exist but it is fleeting due to its high reactivity.
I was able to find a reference on the analogous dichlorosilylene, and I also found some information on difluorosilylene, also known as silicon difluoride, both of which have silicon in the +2 state and react similarly to a carbene.
So yes, both $\ce{CCl2}$ and $\ce{SiCl2}$ exist where the central atom in the +2 oxidation state.
Tin(II) chloride fill its octet by way of either bridging chloride bonds in the crystal structure or hydration bonds in water (see Wikipedia images). The structure of solid $\ce{GeCl2}$ isn't given, but I would expect something similar. I'll update if I find anything.
