Synthesis and Structural Comparison of a Series of Divalent Ln(TpR,R‘)2 (Ln = Sm, Eu, Yb) and Trivalent Sm(TpMe2)2X (X = F, Cl, I, BPh4) Complexes

Reaction of LnI2 (Ln = Sm, Yb) with two equivalents of NaTpMe2 or reduction of Eu(TpMe2)2OTf gives good yields of the highly insoluble homoleptic Ln(II) complexes, Ln(TpMe2)2 (Ln = Sm (1a), Yb (2a), Eu (3a)). Use of the additionally 4-ethyl substituted TpMe2,4Et ligand produces the analogous, but soluble Ln(TpMe2,4Et)2 (1−3b) complexes. Soluble compounds are also obtained with the TpPh and TpTn ligands (Tn = thienyl), Ln(TpPh)2 (Ln = Sm, 1c; Yb, 2c) and Ln(TpTn)2 (Ln = Sm, 1d; Yb, 2d). To provide benchmark parameters for structural comparison the series of Sm(TpMe2)2X complexes (X = F, 1e; Cl, 1f; Br, 1g; I, 1h; BPh4, 1j) were prepared either via oxidation of the Sm(TpMe2)2 or salt metathesis from SmX3 (X = Cl, Br, I). The solid-state structures of 1−3a, 1b, 1−2c and 1e, 1f, 1h, and 1j were determined by single-crystal X-ray diffraction. The homoleptic bis-Tp complexes are all six-coordinate with trigonal antiprismatic geometries, planes of the κ3-Tp ligands are parallel to one another. In the series of S...