Manuscript number: asia.202400964 Synthesis and structures of oxide -centred alkali metal (K, Li)/lanthanoid (Ln3 or 4) 3,5-dimethylpyrazolate cages - Herbert Schumann revisited.

Reaction of lanthanoid tris(3,5-dimethylpyrazolate) compounds, [Ln(Me2pz)3(thf)]2 (Ln = La 1a, Ce, Pr, Dy 1b, Yb, Lu) with potassium or lithium bistrimethylsilylamide and with or without added 3,5-dimethylpyrazole, or of lanthanoid tris(bistrimethylsilyl)amide complexes with potassium bistrimethylsilylamide and 3,5-dimethylpyrazole have yielded a variety of oxide centred Ln3 or Ln4/(K or Li)1-3 multinuclear cages, namely, [La4O(Me2pz)11K(thf)2] (2a), [La4O(Me2pz)11Li(Me2pzH)]⋅0.5Hexane (2b), [La4O(Me2pz)10(Me2pzH)] (2c) (from heating 1a in toluene), [Ce3O(Me2pz)9K2(dme)2] (3a), [Ce3O(Me2pz)9Li2(thf)2]⋅0.5Hexane (3b) and [Ce(Me2pz)5Li2(thf)3] (3c), which crystallized together, [Ce3O(Me2pz)10K3(thf)3] (3d), [Pr3O(Me2pz)10K3(thf)3] (4), [Dy3O(Me2pz)9K2(thf)2]·THF (5), [Yb3O(Me2pz)9K2(thf)2]·THF (6), and [Lu3O(Me2pz)9K2(thf)2]⋅THF (7). Crystals of {[K8(Me2pz)8(thf)2]⋅THF}∞ (8) were also obtained from the preparation of 7. From reaction of [Ce(Me2pz)3(thf)]2 with potassium tert-butoxide in toluene, the cerium(IV) heterobimetallic polymer [Ce2(Me2pz)6(OtBu)4K2]∞ (9) was isolated. In the Ln3O and the Ln4O cages, the Ln atoms have triangular and distorted tetrahedral arrangements about the central oxygen, respectively. All metals are bound to the cages by a variety of pyrazolate binding modes, with up to five different exhibited in some structures, and a new coordination mode, μ4-1κ(N):2κ(N'):η5:η5, was observed in two complexes.
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