Syntheses and crystal structures of [(C6H5CH2C5H4)2GdCl.THF]2 and (C6H5CH2C5H4)2ErCl.THF

[(C₆H₅CH₂C₅H₄)₂GdCl.THF]₂ (1) and (C₆H₅CH₂C₅H₄)₂ErCl.THF (2) were prepared by the reaction of LnCl₃ (Ln? Gd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2₁/c space group with a=1.1432(2), b=1.2978(2), c=1.7604(3) nm, β=108.75(2), V=2.4732(9) nm³, Z=2(four monomers), D_c“1.54 g.cm^?3. R=0.0342 and R_w“0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P2₁2₁2₁ space group with a=0.8645(2), b=1.1394(3), c=2.5289(4) nm, V=2.4919(9) nm³, Z=4, D_c“1.56 g.cm^?3. R=0.0514, R_w“0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd³⁺ are located in the opposite direction (139°); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er³⁺ are located in the same direction (6.5°).