Small steric variations in ligands with large synthetic and structural consequences

Journal Publication ResearchOnline@JCU
Qayyum, Sadaf;Haberland, Kristina;Forsyth, Craig M.;Junk, Peter C.;Deacon, Glen B.;Kempe, Rhett
Abstract

The reaction of ytterbium metal with the aminopyridines2,6-(diisopropylphenyl)-[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (1, Ap'H) and (2,4,6-trimethylphenyl)-[6-(2,4,6-trimethylphenyl)pyridin-2-yl]amine (2, ApMeH) at elevated temperature under vacuum in the presence of mercury gave rise to divalent [Yb(Ap')2] (3) and trivalent [Yb(ApMe)3] (4), respectively. The single-crystal X-ray structure analysis of 3 revealed a four-coordinate ytterbium atom with two chelating (N,N') Ap' ligands inclined to each other at an angle of 126.93(7)° (Cl–Yb–C26). Additionally the complex forms intermolecular CAryl–H agostic interactions [Yb1···C17 2.981(2) Å and Yb1···H17 2.56(3) Å] (all H atoms refined). Complex 4 contains a six-coordinate ytterbium atom having three chelating (N,N') ApMe ligands and has distorted octahedral stereochemistry. The reaction of the potassium salts of Ap'H (5) and ApMeH (6) with [YbI2 (thf)4] in thf gave rise to the divalent lanthanoid complexes [Yb(Ap')2(thf)] (7), and [Yb(ApMe)2(thf)2] (8), respectively, and 7 was also obtained by redox transmetallation/ligand exchange from Yb metal, HgPh2 and Ap'H. X-ray crystal structures show that 7 and 8 have five- and six-coordinate ytterbium atoms and distorted trigonal-bipyramidal and distorted octahedral stereochemistry, respectively, the difference in coordination number reflecting the difference in steric demand of the Ap' and ApMe ligands.

Journal

European Journal of Inorganic Chemistry

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2008

ISBN/ISSN

1099-0682

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Issue

4

Pages Count

6

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Publisher

Wiley

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DOI

10.1002/ejic.200701098