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

The reaction of YbI 2 with KTp Me2 gives (Tp Me2 )YbI(THF) 2 (1-Yb) as a thermally unstable product. Use of the more hindered KTp tBu,Me gave (Tp tBu,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 [(Tp tBu,Me )YbIL n ] (L = CN t Bu, n = 1; L = 3,5-lutidine, n = 2) are described. 2-Sm can be oxidized using AgBPh 4 to give [(Tp tBu,Me )SmI(THF) 2 ]BPh 4 . 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 (Tp tBu,Me )Ln{CH(SiMe 3 ) 2 } (Ln = Sm, 5-Sm; Yb, 5-Yb) and [(Tp tBu,Me )Ln{CH 2 (SiMe 3 )}(THF)] (Ln = Yb, 6a-Yb) and the triethylborohydrides [(Tp tBu,Me )Ln(HBEt 3 )(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 [(Tp tBu,Me )Sm{CH(SiMe 3 ) 2 }(THF)], 5a-Sm. © 2011 The Royal Society of Chemistry.