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

Publication Name

Zeitschrift fuer Anorganische und Allgemeine Chemie

Volume

645

ISBN/ISSN

1521-3749

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Publisher

Wiley-Blackwell

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DOI

10.1002/zaac.201900015