Synthesis and Structural Comparison of a Series of Divalent Ln(Tp^R,R‘)₂(Ln = Sm, Eu, Yb) and Trivalent Sm(Tp^Me₂)₂X (X = F, Cl, I, BPh₄) Complexes

Abstract

Reaction of LnI2 (Ln = Sm, Yb) with two equivalents of NaTp(Me2) or reduction of Eu(Tp(Me2))2OTf gives good yields of the highly insoluble homoleptic Ln(II) complexes, Ln(Tp(Me2))2 (Ln = Sm (1a), Yb (2a), Eu (3a)). Use of the additionally 4-ethyl substituted Tp(Me2,4Et) ligand produces the analogous, but soluble Ln(Tp(Me2,4Et))2 (1-3b) complexes. Soluble compounds are also obtained with the Tp(Ph) and Tp(Tn) ligands (Tn = thienyl), Ln(Tp(Ph))2 (Ln = Sm, 1c; Yb, 2c) and Ln(Tp(Tn))2 (Ln = Sm, 1d; Yb, 2d). To provide benchmark parameters for structural comparison the series of Sm(Tp(Me2))2X complexes (X = F, 1e; Cl, 1f; Br, 1g; I, 1h; BPh4, 1j) were prepared either via oxidation of the Sm(Tp(Me2))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 kappa(3)-Tp ligands are parallel to one another. In the series of Sm(Tp(Me2))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(Tp(Me2))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(Tp(Me2))2](+) fragment can make available and the donor ability of the anionic group toward the hard Sm(III) center.

Steric Modulation of Coordination Number and Reactivity in the Synthesis of Lanthanoid(III) Formamidinates

“…Akin to lanthanoid complexes of the smaller N,N ′‐bis(aryl)formamidinates, the geometry about the lanthanoid centres of the 6 Ln species can be described as a trigonal prism with trigonal faces composed of N(1)F(1)N(4):N(2)O(1)N(3) ( 6 Ce ; Figure 7, Table 4, Scheme ). These mononuclear [LnL 2 F] complexes boast not only a rare terminal fluoride,8, 10, 12c, 13c, 36 but are also the first lanthanoid fluorides supported by organoamide ligands. Comparison with the few terminal LnF complexes indicates similar metric parameters, for example, higher coordinate [Sm(Tp*) 2 (F)] (SmF 2.089(3) Å; 6 Sm 2.093(2) Å),8, 36 and [Ce(1,2,4‐ t Bu 3 C 5 H 2 ) 2 F] (CeF 2.165(4) Å,13c 6 Ce 2.1217(15) Å).…”

“…These mononuclear [LnL 2 F] complexes boast not only a rare terminal fluoride,8, 10, 12c, 13c, 36 but are also the first lanthanoid fluorides supported by organoamide ligands. Comparison with the few terminal LnF complexes indicates similar metric parameters, for example, higher coordinate [Sm(Tp*) 2 (F)] (SmF 2.089(3) Å; 6 Sm 2.093(2) Å),8, 36 and [Ce(1,2,4‐ t Bu 3 C 5 H 2 ) 2 F] (CeF 2.165(4) Å,13c 6 Ce 2.1217(15) Å). The Ln(1)F(1) bonding of the 6 Ln complexes is consistent with a reduction in lanthanoid radius across the series (Table 4).…”

Variable nuclearity scorpionate-supported lanthanide polyhydrides: [(TpR,R′)LnH2]n (n=3, 4 and 6)

“…The yields of the hydride clusters 1 range from reasonable (Y) to moderate (Nd, Sm and Lu), but poor for Yb. The complex 1-Yb is unstable in solution and, during attempted crystallization deposits the very insoluble, purple divalent Yb(Tp Me2 ) 2 [24], formation of the latter is already observed during the hydrogenolysis reaction. Although analytically pure 1-Yb could not be obtained the tetranuclear cluster formulation was corroborated by solid-state X-ray structure determination (vide infra).…”

“…Although analytically pure 1-Yb could not be obtained the tetranuclear cluster formulation was corroborated by solid-state X-ray structure determination (vide infra). Small amounts of the similarly insoluble, purple Sm(Tp Me2 ) 2 [24] was also observed in the synthesis of 1-Sm, but the solution stability of this complex far exceeds that of 1-Yb.…”

Intramolecular Metal–Fluorocarbon Coordination, CF Bond Activation and Lanthanoid–Fluoride Clusters with Tethered Polyfluorophenylamide Ligands

“…In many cases, lanthanoid-induced C À F activation leads to the formation of heteroleptic fluorides, [4,19,[21][22][23][24][25]27] [Ln(L) 2 F], [Ln(L)F 2 ], or more complex species including cages and rings. [19, 22, 23, 27a,c] Other examples of these compounds have been made by selective deprotonation of tris(cyclopenta-A C H T U N G T R E N N U N G dienyl)lanthanoids [28] and by SnÀF [29] and PbÀF [30] activation, but rare earth heteroleptic fluorides remain a limited class. Their existence is of considerable interest given the potential for rearrangement into the corresponding highly stable and insoluble LnF 3 compounds.…”