The 4n Series Method has been utilized to categorize, analyze and predict structures for transition metal carbonyl, borane, hydrocarbon and Zintl ion clusters. The method is being extended to study carbonyl chalcogenide clusters. Adequate examples have been given to demonstrate the application of the 4n series method to categorize clusters and where possible predict their possible skeletal structures. In this paper, the method is being applied to the study of carbonyl chalcogenide cluster complexes. What has been found is the striking structural similarity of a wide range of carbonyl chalcogenide clusters to those of corresponding hydrocarbon clusters. It was observed that when a derived hydrocarbon from a cluster, F CH = C n H q , is such that nq, the "hydrocarbon character" becomes reduced and the typical cluster tendencies increase. When n = q, the situation becomes more or less a borderline case. When q=0, then F CH = C n . When the series becomes bi-capped or more, then the equivalent carbon cations are obtained.