contains Al3+ and C4-
but it is exception.
some more exception are calcium carbide (CaC2 ). There are some organic ionic compounds, such as sodium acetate (NaCH3CO2 ), in which the formal charge is not on a carbon atom...
but normaly carbon dosen 't form becose To get a stable octet by ionic bonding, carbon would have to either lose 4 electrons or gain 4 electrons. Either process would take way too much energy