Two Routes of Electrophilic Addition and Unexpected Cluster Core Transformation in the Reactions of the K2[Fe3(μ3‐Q)(CO)9] (Q = Se, Te) Clusters with iPr2PCl

The reactions of the K2[Fe3(μ3-Q)(CO)9] (Q = Se (K2[1a]), Te (K2[1b])) clusters with iPr2PCl in THF lead to the formation of mixtures of two products: [{Fe2(CO)6(μ-PiPr2)}2(μ4,η2-Q2)] (2a, 2b) and [Fe3(μ3-Q)(μ-PiPr2)2(CO)7] (3a, 3b). The compounds 3a and 3b are the products of addition of two {PiPr2}+ units to two Fe-Fe edges of the initial cluster accompanied by the elimination of two CO-ligands. The compounds 2a and 2b are the products of the initial cluster core fragmentation followed by assembling of the diiron fragments via Q–Q bond formation. In contrast to that the reaction of K2[1a] with iPr2PCl in CH2Cl2 leads mostly to the electrophilic insertion of {PiPr2}+ into the Se–Fe bond and formation of [(μ-H)Fe3(μ3,η2-SePiPr2)(CO)9] (4a). Reaction of K2[1b] with iPr2PCl in CH2Cl2 leads primarily to unstable unidentified products, although 2b and 3b in minor amounts present in the reaction solution. The crystal structures of 2a, 2b, 3a and 4a were determined by single-crystal X-ray diffraction.