Potential precursors for terminal ytterbium(II) imide complexes bearing the hydrotris(3- tert -butyl-5-methylpyrazolyl)borato ligand.

Monomeric, divalent ytterbium primary amides Tp t Bu,Me Yb(NHR)(thf) x (R = C 6 H 3 iPr 2 -2,6 = Ar iPr = Dipp, C 6 H 3 (CF 3 ) 2 -3,5 = Ar CF3 , SiPh 3 ) supported by the bulky hydrotris(3- t Bu-5-Me-pyrazolyl)borato scorpionate ligand are synthesized acccording to salt metathesis and protonolysis protocols, respectively. Yb(II) precursors comprise YbI 2 (thf) 2 , Yb[N(SiMe 3 ) 2 ] 2 (thf) 2 and Tp t Bu,Me Yb[N(SiMe 3 ) 2 ]. Complexes Tp t Bu,Me Yb(NHR)(thf) x readily engage in donor (thf) exchange with nitrogen donors like DMAP (4-dimethylaminopyridine) and pyridine. Treatment of Tp t Bu,Me Yb(NHAr CF3 )(thf) 2 with the Lewis acids AlMe 3 and GaMe 3 results in the heterobimetallic complexes Tp t Bu,Me Yb(NHAr CF3 )(MMe 3 ) (M = Al, Ga). Reactions of Tp t Bu,Me Yb(NHR)(thf) x (R = Ar iPr , Ar CF3 ) with the halogenating agents C 2 Cl 6 and TeBr 4 give access to trivalent complexes [Tp t Bu,Me Yb(NHR)(X)] (X = Cl, Br). The ytterbium(II) complexes under study display 171 Yb NMR chemical shifts in the range 582 ppm for Tp t Bu,Me Yb(NHAr CF3 )(GaMe 3 ) to 954 ppm for Tp t Bu,Me Yb(NHSiPh 3 )(dmap). The salt-metathesis route is also applicable for the synthesis of complexes Tp t Bu,Me Ln(NHAr iPr )(thf) (Ln = Sm, Eu) and Tp t Bu,Me Yb(NHAr Me ) (Ar Me = C 6 H 3 Me 2 -2,6).