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The Synthesis, Structures and Polymorphism of the Dimeric Trivalent Rare‐Earth 3,5‐Dimethylpyrazolate Complexes [Ln(Me 2 pz) 3 (thf)] 2
Author(s) -
Deacon Glen B.,
Harika Rita,
Junk Peter C.,
Skelton Brian W.,
Werner Daniel,
White Allan H.
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201400099
Subject(s) - chemistry , lanthanide , tetrahydrofuran , crystallography , homoleptic , pyridine , crystal structure , lanthanide contraction , cerium , metal , ligand (biochemistry) , coordination number , stereochemistry , ion , medicinal chemistry , inorganic chemistry , solvent , biochemistry , receptor , organic chemistry
A variety of rare‐earth 3,5‐dimethylpyrazolate (Me 2 pz) complexes have been synthesised by (i) the direct reaction of Hg‐activated metal with Me 2 pzH as a pro‐ligand at elevated temperatures, (ii) by redox transmetalation/protolysis with the lanthanoid element, Hg(C 6 F 5 ) 2 , and Me 2 pzH, and (iii) by protolysis of tris[bis(trimethylsilyl)amido]cerium(III) with Me 2 pzH. Each product, upon crystallisation from tetrahydrofuran (thf), formed a dimeric complex, [Ln(Me 2 pz) 3 (thf)] 2 (Ln = La, Ce, Pr, Nd, Ho, Yb, or Lu). Despite the common formulation, two completely different structures were observed in two distinct crystallographic “domains of existence”, together presumptively spanning the gamut of Ln and Y. For the larger rare‐earth ions (La–Pr), there are two terminal η 2 ‐Me 2 pz ligands and one thf donor on each Ln atom, with the metal atoms being linked by a pair of bridging pyrazolate ligands of an uncommon type (η 2 :η 5 ), resulting in formal ten‐coordination. A Me 2 pzH complex [Ce(Me 2 pz) 3 (Me 2 pzH)], although not isomorphous, has a similar structure. For the smaller rare‐earth elements (Nd–Lu), the bridging is entirely different, with two μ‐κ 1 ( N ):κ 1 ( N ) pyrazolate and two unusual bridging thf ligands. Each Ln atom also has two chelating Me 2 pz ligands, resulting in formal eight‐coordination. Crystallisation of [Nd(Me 2 pz) 3 (thf)] 2 from pyridine yields monomeric, nine‐coordinate [Nd(Me 2 pz) 3 (pyridine) 3 ] with only chelating Me 2 pz ligands.