Stable heteroleptic complexes of divalent lanthanides with bulky pyrazolylborate ligands--iodides, hydrocarbyls and triethylborohydrides.

The reaction of YbI2 with KTpMe2 gives (TpMe2)YbI(THF)2 (1-Yb) as a thermally unstable product. Use of the more hindered KTptBu,Me gave (TptBu,Me)LnI(THF)n (Ln = Sm, n = 2, 2-Sm; Ln = Yb, n = 1, 2-Yb). The crystal structures of both these compounds are reported. Adducts with neutral ligands such as pyridines and isonitriles can be prepared and the crystal structures of [(TptBu,Me)YbILn] (L = CNtBu, n = 1; L = 3,5-lutidine, n = 2) are described. 2-Sm can be oxidized using AgBPh4 to give [(TptBu,Me)SmI(THF)2]BPh4. Compounds 2-Sm and 2-Yb are useful starting materials for the preparation of heteroleptic compounds by metathesis with appropriate potassium reagents. The preparations and characterization of the hydrocarbyls (TptBu,Me)Ln{CH(SiMe3)2} (Ln = Sm, 5-Sm; Yb, 5-Yb) and [(TptBu,Me)Ln{CH2(SiMe3)}(THF)] (Ln = Yb, 6a-Yb) and the triethylborohydrides [(TptBu,Me)Ln(HBEt3)(THF)n] (Ln = Sm, n = 0, 7-Sm; Yb, n = 1, 7-Yb) are reported, as well as the crystal structures of 5-Sm and 5-Yb, and the THF adducts 6a-Yb and [(TptBu,Me)Sm{CH(SiMe3)2}(THF)], 5a-Sm.