New homoleptic rare earth 3,5-diphenylpyrazolates and 3,5-di-tert-butylpyrazolates and a noteworthy structural discontinuity

Rad, Nazli E.;Junk, Peter C.;Deacon, Glen B.;Wang, Jun

Abstract

Direct thermally induced reactions between rare earth metals (Ln = Y,Ce, Dy, Ho, and Er) activated by Hg metal and 3,5-diphenylpyrazole (Ph(2)pzH) or 3,5-di-tert-butylpyrazole (tBu(2)pzH) yielded either homoleptic complexes [Ln(n)(R(2)pz)(3n)] or a heteroleptic complex [Ln(Ph(2)pz)(3)(Ph(2)pzH)(2)] From Ph(2)pzH, [Ce-3(Ph(2)pz)(9)], [Dy-2(Ph(2)pz)(6)], [Ho-2(Ph(2)pz)(6)], and [Y(Ph(2)pz)(3)(Ph(2)pzH)(2)] were isolated. The first has a bowed trinuclear Ce-3 backbone with two eta(2) pyrazolate ligands on the terminal metal atoms and one on the middle, and bridging by both mu-eta(2):eta(2) and mu-eta(2):eta(5) ligands between the terminal and the central Ce atoms. Although both the Dy and Ho complexes are dinuclear, the former has the rare mu-eta(2):eta(1) bridging whilst the latter has mu-eta(2):eta(2) bridging. Thus the dysprosium complex is seven-coordinate and the holmium is eight-coordinate, in contrast to any correlation with Ln(3+) ionic radii, and the series has a remarkable structural discontinuity. The heteroleptic Y complex is eight coordinate with three chelating Ph(2)pz and two transoid unidentate Ph(2)pzH ligands. From tBu(2)pzH, dimeric [Ln(2)(tBu(2)pz)(4)] (Ln = Ce, Er) were isolated and are isomorphous with eight coordinate Ln atoms ligated by two chelating terminal tBu(2)pz and two mu-eta(2):eta(2) tBu(2)pz donor groups. They are also isomorphous with previously reported La, Nd, Yb, and Lu complexes.

Journal

Zeitschrift fuer Anorganische und Allgemeine Chemie

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645

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1521-3749

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Wiley-Blackwell

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DOI

10.1002/zaac.201900015