The behavior of [(eta(5):eta(1)-C5H4CH2CH2OMe)ZrCl2(mu-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 (eta(5):eta(1)-C5H4CH2CH2OMe)ZrCl3(MeOH) and (eta(5): eta(1)-C5H4CH2CH2OMe)ZrCl3(H2O) were isolated. An X-ray structure of the thf solvate of the latter compound was determined: space group P2(1)/c, a = 11.612(1) Angstrom, b = 10.759(2) Angstrom, c = 14.291(2) Angstrom, beta = 105.50(1)degrees, V = 1720.5(4) Angstrom(3), 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 [(eta(5)-C5H4CH2CH2-OMe)ZrCl2(H2O)(DMSO)(2)]Cl-+(-) crystallized from the solution: space group P (1) over bar, a = 8.297(1) Angstrom, b = 10.097(1) Angstrom, c = 12.883(1) Angstrom, alpha = 71.12(1)degrees, beta = 86.60(1)degrees, gamma = 87.45(1)degrees, V = 1019.0(2) Angstrom(3), Z = 2, R = 0.049. Compound 1 is a Diels-Alder catalyst even under moist conditions.