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.