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=[ PhiP DippSn⋅Fe⋅IPr] + ; PhiP Dipp={[Ph 2 PCH 2 Si( i Pr) 2 ](Dipp)N}; Dipp=2,6- i Pr 2 C 6 H 3 ; IPr=[(Dipp)NC(H)] 2 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 II -Fe 0 complex 3 leads to oxidative addition of one C-P linkage of the PhiP Dipp ligand in an intermediary Fe -I complex, leading to Fe I 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 d 9 -iron complex.