Abstract
In recent work we have reported the synthesis and physical properties of near-linear Ln(II) (Ln = lanthanide) complexes utilizing the bulky bis(silylamide) {N(SiiPr3)2}. Herein, we synthesize trigonal-planar Ln(II) complexes by employing a smaller bis(silylamide), {N(SitBuMe2)2} (N**), to study the effects of this relatively rare Ln geometry/oxidation state combination on the magnetic and optical properties of complexes. We show that the charge-separated trigonal-planar Ln(II) complexes [K(2.2.2-cryptand)][Ln(N**)3] (Ln = Sm (1), Eu (2), Tm (3), Yb (4)) can be prepared by the reaction of 1.5 equiv of [{K(N**)}2] with LnI2THF2 (Ln = Sm, Yb) or LnI2 (Ln = Eu, Tm) and 1 equiv of 2.2.2-cryptand in Et2O. Complex 3 is the first structurally characterized trigonal-planar Tm(II) complex. In the absence of 2.2.2-cryptand, [K(DME)3][Sm(N**)3] (5) and [Ln(N**)2(μ-N**)K(toluene)2] (Ln = Sm (6), Eu (7)) were isolated in the presence of DME (dimethoxyethane) or toluene, respectively. The 1:1 reaction of [{K(N**)}2] with LnI2THF2 (Ln = Sm, Yb) in THF gave the four-coordinate pseudo-tetrahedral Lewis base adducts [Ln(N**)2(THF)2] (Ln = Sm (8), Yb (9)) and the cyclometalated complex [Yb(N**){N(SitBuMe2)(SitBuMeCH2)}(THF)] (10). Complexes 1-10 have been characterized as appropriate by single-crystal XRD, magnetic measurements, multinuclear NMR, EPR, and electronic spectroscopy, together with CASSCF-SO and DFT calculations. The physical properties of 1-4 are compared and contrasted with those of closely related near-linear Ln(II) bis(silylamide) complexes.
Highlights
F-block complexes are typified by high formal coordination numbers and flexible geometries due to their large ionic radii and predominantly electrostatic bonding regimes.[1]
Divalent precursors were used in this study since, as stated above, we have found that synthetic routes to [Ln(N**)3] starting materials from LnX3 (X = Cl, I) for the smaller Ln ions were plagued by side-reactions, as previously observed with bulky cyclopentadienyl systems.[44]
We have reported a series of anionic trigonal-planar bis(silylamide) complexes comprising the “traditional” divalent metals Sm, Eu, and Yb, together with Tm
Summary
F-block complexes are typified by high formal coordination numbers and flexible geometries due to their large ionic radii and predominantly electrostatic bonding regimes.[1] Distortion from ideal polyhedra is common and is undesirable when specific coordination geometries are sought for particular applications, for example in magnetic[2] or catalytic[3] materials Demanding ligands, such as the archetypical bis(silylamide) {N(SiMe3)2} (N′′), have been frequently utilized to afford metal complexes with low coordination numbers.[4] As N′′ and its group 1 metal salts MN′′5,6 are commercially available or can be synthesized relatively a plethora of complexes of the formula [MIII(N′′)3] with p-,7,8 d-,9 and fblock elements[10,11] have been reported, with their low coordination numbers often providing interesting reactivity profiles.[12] Solid-state structures of [MIII(N′′)3] complexes are typified by either trigonal-planar (D3h) or trigonal-pyramidal (C3v) geometries, with all f-block examples exhibiting the latter shape. We employ a suite of experimental and theoretical techniques to investigate the physical properties of trigonal-planar Ln(II)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
