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

• Published in: Inorganic chemistry Vol. 40; no. 20; pp. 5106 - 5116
• Main Authors: Hillier, Anna C, Zhang, Maunder, Graham H, Liu, Sung Ying, Eberspacher, Todd A, Metz, Mathew V, McDonald, Robert, Domingos, Ângela, Marques, Noémia, Day, Victor W, Sella, Andrea, Takats, Josef
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.09.2001
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic010325w

Reaction of LnI2 (Ln = Sm, Yb) with two equivalents of NaTpMe 2 or reduction of Eu(TpMe 2 )2OTf gives good yields of the highly insoluble homoleptic Ln(II) complexes, Ln(TpMe 2 )2 (Ln = Sm (1a), Yb (2a), Eu (3a)). Use of the additionally 4-ethyl substituted TpMe2,4Et ligand produces the analogous, but soluble Ln(TpMe 2 ,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(TpMe 2 )2X complexes (X = F, 1e; Cl, 1f; Br, 1g; I, 1h; BPh4, 1j) were prepared either via oxidation of the Sm(TpMe 2 )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 Sm(TpMe 2 )2X complexes the structure changes from seven-coordinate molecular compounds, with intact Sm-X bonds, for X = F, Cl, to six-coordinate ionic structures [Sm(TpMe 2 )2]X (X = I, BPh4), suitable crystals of the bromide compound could not be obtained. The dependence of the structures on the size of X is understandable in terms of the interplay between the size of the cleft that the [Sm(TpMe 2 )2]+ fragment can make available and the donor ability of the anionic group toward the hard Sm(III) center.