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

The open-shell cationic stannylene-iron(0) complex 4 (4=[ DippSn⋅Fe⋅IPr] ; Dipp={[Ph PCH Si( Pr) ](Dipp)N}; Dipp=2,6- Pr C H ; IPr=[(Dipp)NC(H)] C:) 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 Ge -Fe complex 3 leads to oxidative addition of one C-P linkage of the Dipp ligand in an intermediary Fe complex, leading to Fe 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 in this unique d -iron complex.