The reaction of Mn-2(CO)(7)(mu-S-2) 1, With Pt(PPh3)(2)(PhC2Ph) yielded the new complex, Mn-2(CO)(6)Pt(PPh3)(2)(mu(3)-S)(2), 3, by loss of CO and insertion of a Pt(PPh3)(2) group into the S-S bond of 1. Complex 3 was characterized crystallographically and was found to consist of an open Mn2Pt cluster with one Mn-Mn bond, 2.8154(14) A, one Mn-Pt bond, 2.9109(10) Angstrom, and two triply bridging sulfido ligands. Compound 3 reacts with CO to form adduct Mn-2(CO)(6)(mu-CO)Pt(PPh3)(2)(mu(3)-S)(2), 4. Compound 4 also contains an open Mn2Pt cluster with two triply bridging sulfido ligands but has only one metal-metal bond, Mn-Mn = 2.638(2) Angstrom. Under nitrogen, compound 4 readily loses CO and reverts back to 3.