Can carbon be the central atom of a complex? Can it form a quadruple bond with itself? [closed]








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Why does $\ce{[C(NH3)2]}$ not exist as a complex? Here, $\ce{C}$ is carbon and the configuration of $\ce{C}$ in ground state is $\ce{[He] 2s^2 2p^2}$.


Can't the two $\ce{NH3}$ molecules pair the two $\ce{p}$ electrons of carbon and form coordinate bond with carbon?


Why does $\ce{C2}$ (one carbon atom bonded with other through quadruple bonds) not exist? Two $\ce{2p}$ orbitals of $\ce{C}$ should form π bonds and one $\ce{2p}$ and one $\ce{2s}$ should form σ bonds with the other $\ce{C}$ (without hybridisation).


I'd appreciate an answer for a beginner.




Asking multiple unrelated questions at once is considered a bad practice, but let's forget that for a moment.


Your first molecule has more or less satisfactory electronic configuration, but that's not enough for the long-term survival. N would be more than willing to relinquish a proton, and C to accept it, and thus in no time you will have $\ce{H2N-CH2-NH2}$, which then may or may not transform into something else.


Your second molecule has been discussed here before on multiple occasions. Long story short, it does exist, but doesn't have a quadruple bond. (Such bonds are known, but not in $\ce{C2}$; they have a [delta component](https://en.wikipedia.org/wiki/Delta_bond), and that requires *d* orbitals). The problem with your description is that the sigma-oriented *2p* orbital of one carbon will interact not just with the similar *2p*, but also with the *2s* orbital of the other. If not for this fact, it would work out pretty much as you expected.


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We may regard oxyanions as complexes with oxide or oxo ligands; indeed such an approach may offer advantages in understanding the electronic structure of some of these ions. In that sense carbonate ion is indeed a complex with carbon as a central atom. 


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