Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands.

Liane Hilfert,Sida Wang,Farid M. Sroor,Phil Liebing,Volker Lorenz,Frank T. Edelmann

doi:10.1107/s2056989016012135

Abstract

Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis-(η5-cyclo-penta-dien-yl)(3-cyclo-propyl-N,N'-diiso-propyl-propynamidinato-κ2N,N')ytterbium(III), [Yb(C5H5)2(C12H19N2)] or Cp2Yb[( i Pr2N)2C-C≡C-c-C3H5] (1) and tris-(3-phenyl-N,N'-di-cyclo-hexyl-propynamidinato-κ2N,N')ytterbium(III), [Yb(C21H27N2)3] or Yb[(CyN)2C-C≡C-Ph]3 (Cy = cyclo-hex-yl) (2) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2, the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for Mr, μ etc. do not take these into account.

Highlights

Anionic amidinate ligands of the type [RC(NR0 )2] (R = H, alkyl, aryl; R0 = alkyl, cycloalkyl, aryl, SiMe3) are highly useful and versatile spectator ligands in organolanthanide chemistry
Over the past ca 25 years, lanthanide amidinates have witnessed an impressive transformation from laboratory curiosities to homogeneous catalysts as well as valuable precursors in materials science
We describe the synthesis and structural characterization of two new ytterbium(III)

Summary

Chemical context

Anionic amidinate ligands of the type [RC(NR0 )2] (R = H, alkyl, aryl; R0 = alkyl, cycloalkyl, aryl, SiMe3) are highly useful and versatile spectator ligands in organolanthanide chemistry. These readily available N-chelating ligands are generally regarded as sterically demanding cyclopentadienyl equivalents (Collins, 2011; Edelmann, 2013). The cyclopropyl group was chosen because of the well-known electrondonating ability of this substituent to an adjacent electrondeficient atom or group This would give us the rare chance to electronically influence the amidinate ligand system rather than altering only its steric demand.

Structural commentary

Supramolecular features

Database survey

Synthesis and crystallization

Refinement