Reactions of lanthanide triiodides with potassium bistrimethylsilyl amide have been investigated. For lanthanum, recrystallisation from THF-toluene led to monocrystals of the dimeric bisamide [La(mu -I){N(TMS)(2))(2)(THF)](2). We have shown that samarium diiodide and lanthanide triiodides are efficient for lanthanum and samarium reactions, a mixture of tris amides and iodo bisamides is obtained, while only the latter compound is obtained for ytterbium. (C) 2001 Elsevier Science B.V. All rights reserved.