Aqua Complexes of [(2-Methoxyethyl)cyclopentadienyl]zirconium Trichloride

The behavior of [(η5:η1-C5H4CH2CH2OMe)ZrCl2(μ-Cl)]2 (1) toward a variety of solvents, and especially water, was investigated. The bidentate coordination of the C5H4CH2CH2OMe ligand is retained in chloroform, dichloromethane, benzene, acetone, thf, and acetonitrile. No stable adducts of 1 with the last three solvents could be isolated. In methanol and water, coordination of the ether side chain is broken; however, removal of solvent retains this coordination and the stable mono adducts (η5:η1-C5H4CH2CH2OMe)ZrCl3(MeOH) and (η5:η1-C5H4CH2CH2OMe)ZrCl3(H2O) were isolated. An X-ray structure of the thf solvate of the latter compound was determined: space group P21/c, a = 11.612(1) Å, b = 10.759(2) Å, c = 14.291(2) Å, β = 105.50(1)°, V = 1720.5(4) Å3, Z = 4, R = 0.062. The intramolecular coordination of the ether side chain is also broken in DMSO, but in this case it is not retained after removal of solvent. A cationic aqua complex [(η5-C5H4CH2CH2OMe)ZrCl2(H2O)(DMSO)2]+Cl- crystallized from the solution: space group P1̄, a = 8.297(1) Å, b = 10.097(1) Å, c = 12.883(1) Å, α = 71.12(1)°, β = 86.60(1)°, γ = 87.45(1)°, V = 1019.0(2) Å3, Z = 2, R = 0.049. Compound 1 is a Diels−Alder catalyst even under moist conditions.