The cluster anion [Fe3(CO)9(μ3-S-t-C4H9)]−, which is easily obtained by deprotonation from the cluster compound Fe3(CO)9(μ2-H)(μ3-S-t-C4H9), reacts with XCl2 by elimination of t-C4H9Cl and Cl− to give the clusters Fe3(CO)9(μ3-S)(μ3-X) (X = PR: I, X = AsR: II, X = SO: III), in which one edge of the iron triangle is opened. The μ3-PR-bridged clusters I can also be obtained by reactions of SCl2 with the