Most molecular carbido complexes are clusters, usually featuring carbide as a six-fold bridging ligand. Examples include [C(CO)], and [C(CO)]. Though exceptions exist, such as the nonanuclear Ruthenium cluster (μ-C)Ru(CO) (μ-η: η:η-CH) containing a tripped trigonal prism geometry around the carbide.
The iron carbonyl carbides exist not only in the encapsulated carbon ([C(CO)]) but also with exposed carbon centres as in FeC(CO) and FeC(CO)
Bimetallic and exotic clusters such as metal carbide clusterfullerenes (MCCF's) have also been able to be prepared.