William J. Evans, Michael A. Greci, Mohammad A. Ansari and Joseph W. Ziller
Structural evidence has been obtained which suggests that the monoanionic polydentate moiety, Zr2(OPri)9–, obtainable from KZr2(OPri)9 and Zr2(OPri)8(PriOH)2, can function as a replacement for cyclopentadienyl-containing ligand sets in established types of organolanthanide compounds. The Zr2(OPri)9– unit has been found to replace the ligand set [(C5Me5)(thf)2]– (thf = tetrahydrofuran) in [(C5Me5)(thf
)2Sm(µ-I)]2 and the ligand set [(C5H5)2]2– in [(C5H5)2Nd(thf
)(µ-Cl)]2. The complex KZr2(OPri)9 reacts with LnI2(thf
)2 (Ln = Eu or Sm) in toluene to form the isostructural, isomorphous complexes {[Zr2(OPri)9]Ln(µ-I)}2, which crystallize from toluene (1: {[Zr2(OPri)9Eu(µ-I)}2, P21/n, a = 12.082(2), b = 19.309(3), c = 17.294(3) Å, β = 92.805(11)°, U = 4029.4(12) Å3 and Dc = 1.637 g cm–3 for Z = 2; 2: {[Zr2(OPri)9]Sm(µ-I)}2, P21/n, a = 12.071(2), b = 19.273(3), c = 17.279(2) Å, β = 92.679(12)°, U = 4015.4(8) Å3 and Dc = 1.640 Mg m–3 for Z = 2). The face-sharing bioctahedral Zr2(OPri)9– unit uses two of its central isopropoxide ligands and one additional isopropoxide on each zirconium to attach to the lanthanide metal, which has a distorted octahedral co-ordination environment completed by two bridging iodide ligands. The complex Zr2(OPri)8(PriOH)2 reacts with NdCl3 in thf to form {[Zr2(OPri)9]NdCl(µ-Cl)}2 3, which crystallizes from toluene [C
2/c, a = 25.283(5), b = 12.505(3), c = 18.162(2) Å, β = 119.802(9)°, U = 8553.6(22) Å3 and Dc = 1.515 Mg m–3 for Z = 4]. In 3 the Zr2(OPri)9– unit again functions as a tetradentate ligand as in 1 and 2. Two bridging and one terminal chloride complete the pentagonal bipyramidal environment of Nd. A derivative of 3 in which the terminal chlorides are replaced by bridging pivalate groups is obtained by reacting NdCl3 with KO2CBut and Zr2(OPri)8(PriOH) in thf to form {[Zr2(OPri)9]Nd(µ-O2CBut)(µ-Cl)}2 4, which crystallizes from toluene [P
, a = 12.267(3), b = 14.217(4), c = 14.700(3) Å, α = 88.08(2), β = 71.98(2), γ = 78.37(2)°, U = 2386.7(10) Å3 and Dc = 1.485 Mg m–3 for Z = 1].