Synthesis and structural characterization of mononuclear iron(II) ferracarboranes

Article abstract of DOI:10.1021/om00049a028

Neutral iron(II) ferracarboranes of the type [closo-3-CO-3-L-3-L′-3,1,2-FeC₂B₉H₁₁] (3, L = CO, L′ = PPh₃; 4, L = PPh₃, L′ = CH₃CN; 5, L = CO, L′ = CH₃CN; 6, L = CO, L′ = P(OCH₃)₃; 7, L = L′ = P(OCH₃)₃; 8, L = L′ = CO) have been prepared by the Cu(I) oxidation of the dimeric iron dicarbollide complex [closo-3-CO-3,3′-(μ-CO)-3,1,2-FeC₂B₉H ₁₁]₂^2- (2) in the presence of the designated monodentate ligands. Complexes 3, 4, 7, and 8 have been structurally characterized by single-crystal X-ray diffraction. Crystallographic parameters are as follows (compound: crystal system: space group; crystal parameters; Z; unique data (I > 3σ(I)); R,R_w). 3: monoclinic; A2/a; a = 18.384 (3) A?, b = 12.762 (2) A?, c = 23.059 (3) A?, β = 104.081 (4)°; 8; 1780; 7.4, 8.8. 4: monoclinic; C2/c; a = 28.050 (2) A?, b = 11.5715 (9) A?, c = 19.042 (2) A?, β = 116.846 (2)°; 8; 1702; 6.5, 7.7. 7: orthorhombic; Pbnm (standard setting Pnma); a = 10.397 (2) A?, b = 14.419 (3) A?, c = 15.092 (3) A?; 4; 1051; 7.1, 8.9. 8: monoclinic; P2₁/n; a = 6.971 (4) A?, b = 15.900 (9) A?, c = 11.237 (7) A?, β = 91.42 (2)°; 4; 1108; 6.2, 7.4. The closo 12-vertex icosahedral geometry comprising a polyhedral (d⁶Fe)C₂B₉ framework and the pseudooctahedral coordination exhibited by the iron atom are common structural features displayed by all four ferracarboranes.