Organometallic Compounds of the Lanthanides. 141.¹ Synthesis, Molecular Structure, and Solution Behavior of Some Lanthanum(III) and Ytterbium(II) Complexes Containing New Tridentate 1,2- and 1,3-Bis(2-(dimethylamino)ethyl)cyclopentadienyl Ligands

K[C 5 H 4 (CH 2 CH 2 NMe 2 )] reacts with 2-(dimethylamino)ethyl chloride in THF, forming an inseparable 1.5:1 mixture of isomeric 1,2- and 1,3-disubstituted bis((dimethylamino)ethyl)cyclopentadiene, which on deprotonation with KH gives a mixture of the corresponding potassium salts K[1,2-C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 ] (K[1,2-Do 2 C 5 H 3 ]; 1 ) and K[1,3-C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 ] (K[1,3-Do 2 C 5 H 3 ]; 2 ). Addition of LaI 3 (THF) 3 to the mixture of 1 and 2 suspended in THF causes the formation of the half-sandwich complexes (η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,2)LaI 2 (THF) ( 3 ) and (η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,3)LaI 2 (THF) ( 4 ), which can successfully be separated because of their different crystal shapes. The analogous reaction with YbI 2 (THF) 2 causes the precipitation of crystalline (η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,2)YbI(THF) 2 ( 5 ). The noncrystallizing 1,3-isomer left in solution reacts with (C 5 Me 5 )Na, forming the polymeric mixed-metallocene ate complex {Na[μ 2 -(η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,3)(η 5 -C 5 Me 5 )Yb(μ 2 -I)Yb[μ 2 -(η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,3)(η 5 -C 5 Me 5 )} n ( 6 ). The reaction of 5 with (C 5 Me 5 )K or (C 5 H 4 t Bu)Na results in the formation of the sandwich complexes (η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,2)Yb(η 5 -C 5 H 4 t Bu) ( 7 ) and (η 5:η 1:η 1 -C 5 H 3 (CH 2 CH 2 NMe 2 ) 2 -1,2)Yb(η 5 -C 5 Me 5 ) ( 8 ), respectively. The novel compounds have been characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Additionally, X-ray structural analyses of 3 − 8 were performed.