Abstract[(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 witha=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),Dc“1.54 g.cm−3.R=0.0342 andRw“0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic,P212121space group witha=0.8645(2),b=1.1394(3),c=2.5289(4) nm,V=2.4919(9) nm3,Z=4,Dc“1.56 g.cm−3.R=0.0514,Rw“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 d