Deprotonation of Iron Vinylidene Complexes Containing a dppe Ligand
摘要:
Two iron complexes each containing a 1-ferra-2,5-diphospha-[2.1.1] ring are prepared by deprotonation reaction of cationic vinylidene complexes [Fe]CC(Ph)CH2R+ ([Fe] = (eta(5)-C5H5)(dppe)Fe, R = CHCH2 and Ph). The deprotonation takes place at the methylene proton of the dppe ligand, which is followed by an intramolecular addition giving the product. For similar vinylidene complexes with R = CN, p-C6H4CN, and p-C6H4CF3, the deprotonation reaction gave the cyclopropenyl complexes. The deprotonation of the vinylidene complex with R = C6F5 gave both the cyclopropenyl complex and the product containing a 1-ferra-2,5-diphospha-[2.1.1] ring system. The electron-withdrawing ability of the substituent near the C-gamma-methylene group of the vinylidene ligand determines the selectivity of deprotonation. Characterizations of vinylidene, cyclopropenyl complexes, and a complex containing a 1-ferra-2,5-diphospha-[2.1.1] ring are carried out using single-crystal X-ray diffraction analysis.