Cationic Tetrylene-Iron(0) Complexes: Access Points for Cooperative, Reversible Bond Activation and Open-Shell Iron(−I) Ferrato-Tetrylenes**

Abstract

The open-shell cationic stannylene-iron(0) complex 4 (4=[PhiPDippSn⋅Fe⋅IPr]+; PhiPDipp={[Ph2PCH2Si(iPr)2](Dipp)N}; Dipp=2,6-iPr2C6H3; IPr=[(Dipp)NC(H)]2C:) cooperatively and reversibly cleaves dihydrogen at the Sn−Fe interface under mild conditions (1.5 bar, 298 K), in forming bridging hydrido-complex 6. The One-electron oreduction of the related GeII−Fe0 complex 3 leads to oxidative addition of one C−P linkage of the PhiPDipp ligand in an intermediary Fe−I complex, leading to FeI phosphide species 7. One-electron reduction reaction of 4 gives access to the iron(−I) ferrato-stannylene, 8, giving evidence for the transient formation of such a species in the reduction of 3. The covalently bound tin(II)-iron(−I) compound 8 has been characterised through EPR spectroscopy, SQUID magnetometry, and supporting computational analysis, which strongly indicate a high localization of electron spin density at Fe−I in this unique d9-iron complex.