Cleavage of the Fe—Fe Bond of （Me2SiSiMe2） [η^5－C5H4Fe（CO）2]2 with Na／Hg and Molecular Structure of the Ring－Opened Complex

The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain.

Cleavage of the Fe–Fe Bond of (Me2SiSiMe2)[η5‐C5H4Fe (CO)2]2 with Na/Hg and Molecular Structure of the Ring‐Opened Complex

The reaction of the title cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe—Fe bond to afford bis‐sodium salt (Me₂SiSiMe₂) [η⁵‐C₅H₄Fe (CO)₂Na]₂ (4). The latter was not isolated and was used directly to react with MeI, PhCH₂Cl, CH₃C(O)Cl, PhC(O)Cl, Cy₃SnCl (Cy = cyclohexyl) or Ph₃SnCl to afford corresponding ring‐opened derivatives (Me₂SiSiMe₂) [η5‐C₅H₄Fe (CO)₃R]₂ [5, R=Me; 6, R = PhCH₂; 7, R = CH₃C(O); 8, R = PhC (O); 9, R = Cy₃Sn or 10, R = Ph₃Sn]. The crystal and molecular structures of 10 were determined by X‐ray diffraction analysis. The molecule took the desired anti conformation around the Si—Si bond. The length of the Si—Si bond is 0.2343(3) nm, which is essentially identical to that in the cyclic structure of 1 [0.2346(4) nm]. This result unambiguously demonstrates that the Si—Si bond in the cyclic structure of 1 is not subject to obvious ring strain.