Reactions of SnMe2-bridged biscyclopentadienes with molybdenum carbonyl to give compounds containing Mo–Sn–Mo units

In the reactions of double-bridged biscyclopentadienes (EMe2)(SnMe2)(RC5H3)2 (E = C (1), E = Si (2 or 4), E = Ge (3)), or single-bridged biscyclopentadiene (SnMe2)(tBuC5H4)2 (5) with Mo(CO)6 in refluxing xylene, the bridging SnMe2 group migrates from the ligand to the molybdenum atoms to give compounds (6–10) containing the Mo–Sn–Mo units; the bridging group EMe2 (E = C or Si in 1, 2, or 4) does not migrate. It is noteworthy that [(η5-C5H5)Mo(CO)3]2SnMe2 (8) obtained from the reaction of (GeMe2)(SnMe2)(C5H4)2 (3) with Mo(CO)6 is a degermylated and SnMe2 group migrated product, another outcome worth mentioning is that the complex 9 is afforded only in the rac-configuration. The stability of complexes (6, 7, and 10) containing the Mo–Sn–Mo unit toward heat and light was also studied. The molecular structures of 6, 9, and 10 were determined by X-ray diffraction.

Graphical abstractReactions of double-bridged biscyclopentadienes (EMe2)(SnMe2)(RC5H3)2 (E = C (1), E = Si (2 or 4), E = Ge (3)), or single-bridged biscyclopentadiene (SnMe2)(tBuC5H4)2 (5) with Mo(CO)6 in the refluxing xylene were studied. The bridging group SnMe2 in the ligands generally migrated twice to the Mo atoms to give compounds (6–10) with the Mo–Sn–Mo structural unit. In addition, the migrating ability of bridging groups EMe2 (E = Sn, Ge, and Si) are compared, and a plausible stepwise migration mechanism is proposed.Figure optionsDownload full-size imageDownload as PowerPoint slide