Cyclopentadienyl Yttrium Complexes Bearing a Fluorinated Aryloxide Functionality

The ligand C5H5(CH2CArF2OH) (3) (ArF = 3,5-C6H3(CF3)2) was prepared in moderate yield
(65%) by ring opening of the epoxide ArF2C(O)CH2 (2) with NaCp. Epoxide 2 was accessible
in two steps from commercially available precursors. Reaction of the dilithium salt of 3 with
YCl3 afforded the ate complex {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}2Y-Li+{THF}2 (4a).
Exposure of 4a to vacuum resulted in partial desolvation to {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}2Y-Li+{THF} (4b). The chloride complex {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}YCl{THF}2 (5) could only be prepared by protonolysis of {Y[N(SiMe3)2]2(THF)2(μ-Cl)}2 with
1 equiv of 3. Metathesis reactions of 5 with 1 equiv of NaN(SiMe3)2, NaCp, and LiCH(SiMe3)2
afforded {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}Y{N(SiMe3)2}{THF}n (6a, n = 2; 6b, n =
1), {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}Y{η5-C5H5}{THF}n (8a, n = 2; 8b, n = 1), and
{η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}Y{CH(SiMe3)2}{THF}2 (9), respectively. Metathesis
of 5 with 2 equiv of Na[N(SiMe3)2] or LiCH(SiMe3)2 afforded the anionic “ate” complexes
{η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}{N(SiMe3)2}2Y-Na+{THF}2 (7) and {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}{CH(SiMe3)2}2Y-Li+{THF}2 (10), respectively. The phenoxide {η5:η1-C5H4[CH2C(O)(3,5-C6H3(CF3)2)2]}Y{O-2,6-t-Bu2C6H3}{THF}2 (11) could not be prepared by
salt metathesis but was isolated by protonolysis of Y[O-2,6-t-Bu2C6H3][CH(SiMe3)2]2[THF]2
with 1 equiv of 3. The crystal structures of ate complex 4a and phenoxide 11 were established
by X-ray crystallography.