Crystal Structure of TaCl(NMe2)4 and Its Reactions with Lithium Amides and Water. Indirect Observation of an Equilibrium among TaCl(NMe2)4, Ta(NMe2)5 and Ta2(μ-Cl)2(NMe2)6Cl2

Reactions of TaCl(NMe 2 ) 4 ( 2 ) with LiNR 2 (R = SiMe 3, Et), yielding Ta(NMe 2 ) 4 (NR 2 ) (R = SiMe 3, 4; Et, 7 ), Ta(NMe 2 ) 5 ( 1 ), (Me 2 N) 3 TaN(SiMe 3 )SiMe 2 CH 2 ( 5 ), and Ta(NMe 2 ) 3 (NEt 2 ) 2 ( 8 ), respectively, suggest the presence of an equilibrium among TaCl(NMe 2 ) 4 ( 2 ), Ta(NMe 2 ) 5 ( 1 ), and Ta 2 (μ-Cl) 2 (NMe 2 ) 6 Cl 2 ( 3 ): 2 2 ⇌ 1 + 0.5 3 . New products Ta(NMe 2 ) 4 (NR 2 ) have been characterized. Ta(NMe 2 ) 4 (NEt 2 ) ( 7 ), Ta(NMe 2 ) 5 ( 1 ), and Ta(NMe 2 ) 3 (NEt 2 ) 2 ( 8 ) are in a slow exchange: 2 7 ⇌ 1 + 8 with an equilibrium constant of K eq = 0.25(0.01) at 90 °C. The following are also reported: X-ray crystal structure and a one-step synthesis of TaCl(NMe 2 ) 4 ( 2 ), reaction of 2 with H 2 O giving Ta 2 (μ-Cl) 2 (μ-O)(NMe 2 ) 6 ( 9 ), X-ray structure of 9, and preparation of LiNEt 2 solid.