Syntheses and crystal structures of [(C 6 H 5 CH 2 C 5 H 4 ) 2 GdCl.THF] 2 and (C 6 H 5 CH 2 C 5 H 4 ) 2 ErCl.THF

[(C 6 H 5 CH 2 C 5 H 4 ) 2 GdCl.THF] 2 (1) and (C 6 H 5 CH 2 C 5 H 4 ) 2 ErCl.THF (2) were prepared by the reaction of LnCl 3 (LnGd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, 1 H NMR, 13 C NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2 1 /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) nm 3 , 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, P 2 1 2 1 2 1 space group with a =0.8645(2), b =1.1394(3), c =2.5289(4) nm, V =2.4919(9) nm 3 , 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 Gd 3+ are located in the opposite direction (139°); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er 3+ are located in the same direction (6.5°).