A Structural Investigation of the D2O Solvated, Acetone Solvated and Nonsolvated 1,4-Diazabicyclo[2.2.2]octane Complexes of the Half Sandwich Moiety [(η 5-C5H5)(CO)2Fe]

Abstract

Two new solvates of the dinuclear salt {(η ⁵-C₅H₅)(CO)₂Fe}₂(μ-DABCO)](BF₄)₂ (DABCO = 1,4-diazabicyclo[2.2.2]octane); 1 (D₂O solvate) and 2 (acetone solvate), and the mononuclear salt [(η ⁵-C₅H₅)(CO)₂Fe(DABCO)]BF₄, 3, have been synthesized and structurally characterized. The D₂O solvate, 1 forms crystals in the triclinic space group P1, the acetone solvate forms crystals in the monoclinic P2₁/c space group, while the unsolvated mononuclear salt, 3, forms crystals in the orthorhombic P2₁2₁2₁ space group. The respective unit cell parameters are: Compound 1, a = 7.66300(10) Å, b = 12.3133(2) Å, c = 13.9629(2) Å, α = 69.179(1) °, β= 77.114(1) ° and γ = 84.282(1) °; Compound 2, a = 17.3633(3) Å, b = 14.1688(3) Å, c = 11.3542(2) Å, β = 99.344(1) °; Compound 3, a=8.9936(2) Å, b=10.8949(3) Å, c=15.3417(4) Å. The DABCO ligand adopts a twisted conformation with N-C-C-N torsion angles ranging between –21.05(12) to –19.31(12) ° and 15.3(2) –15.7(2) ° in 1 and 2, respectively, whereas in 3, the CH₂ groups of each NCH₂CH₂N moiety are almost eclipsed, the torsion angles ranging from –2.89(18) to –1.50(16) °.

KEYWORDS Cyclopentadienyliron dicarbonyl complex, 1,4-diazabicyclo[2.2.2]octane (DABCO), X-ray crystallography.