The reactions of E powder (E=S, Se) with a mixture of Cr(CO)6 and Mn2(CO)10 in concentrated solutions of KOH/MeOH produced two new mixed CrMncarbonyl clusters, [E2CrMn2(CO)9]2− (E=S, ; Se, ). Clusters and were isostructural with one another and each displayed a trigonal-bipyramidal structure, with the CrMn2 triangle axially capped by two μ3-E atoms. The analogous telluride cluster, [Te2CrMn2(CO)9]2− (), was obtained from the ring-closure of Te2Mn2 ring complex [Te2Mn2Cr2(CO)18]2− (). Upon bubbling with CO, clusters and were readily converted into square-pyramidal clusters, [E2CrMn2(CO)10]2− (E=Se, ; Te, ), accompanied with the cleavage of one CrMn bond. According to SQUID analysis, cluster was paramagnetic, with S=1 at room temperature; however, the Se analogue () was spectroscopically proposed to be diamagnetic, as verified by TD-DFT calculations. Cluster could be further carbonylated, with cleavage of the MnMn bond to produce a new arachno-cluster, [Te2CrMn2(CO)11]2− (). The formation and structural isomers, as well as electrochemistry and UV/Vis absorption, of these clusters were also elucidated by DFT calculations.