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. 2016 Oct 4;72(Pt 11):1526-1531.
doi: 10.1107/S2056989016015322. eCollection 2016 Nov 1.

Formation and structure of the first metal complexes comprising amidino-guanidinate ligands

Farid M Sroor  1 , Phil Liebing  2 , Cristian G Hrib  2 , Daniel Gräsing  2 , Liane Hilfert  2 , Frank T Edelmann  2
Affiliations

Formation and structure of the first metal complexes comprising amidino-guanidinate ligands

Farid M Sroor et al. Acta Crystallogr E Crystallogr Commun. .

Abstract

The first metal complexes comprising amidino-guanidinate ligands have been prepared and structurally characterized, namely bis-[μ-N,N',N'',N'''-tetraisopropyl-1-(1-butyl-amidinato)guanidinato-κ3N1,N2:N2]bis-[(tetra-hydro-furan)lithium], [Li2(C18H37N4)2(C4H8O)2], (2), and [bis-(tetra-hydro-furan)-lithium]-di-μ-chlorido-{(N,N'-di-cyclo-hexyl-1-butyl-amidinato-κ2N1,N2)[N,N',N'',N'''-tetra-cyclo-hexyl-1-(1-butyl-amidinato)guanidinato-κ2N1,N2]holmate(III)}, [HoLiCl2(C4H8O)2(C17H31N2)(C30H53N4)], (3). The novel lithium amidino-guanidinate precursors Li[ n BuC(=NR)(NR)C(NR)2] [1: R = Cy (cyclo-hex-yl), 2: R = i Pr) were obtained by treatment of N,N'-diorganocarbodi-imides, R-N=C=N-R (R = i Pr, Cy), with 0.5 equivalents of n-butyl-lithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ-prepared 2 afforded the unexpected holmium 'ate' complex [ n BuC(=NCy)(NCy)C(NCy)2]Ho[ n BuC(NCy)2](μ-Cl)2Li(THF)2 (3) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidino-guanidinate ligand.

Keywords: amidinate ligands; amidino­guanidinate; crystal structure; guanidinate ligands; holmium; lithium.

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Figures

Figure 1
Figure 1
Reaction scheme: Formation of amidino­guanidinate ligands from the reaction of n-butyl­lithium with excess carbodi­imide.
Figure 2
Figure 2
The mol­ecular structure of compound 2 in the crystal. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity. Symmetry operator to generate equivalent atoms: 2 − x, 1 − y, −z.
Figure 3
Figure 3
The mol­ecular structure of compound 3 in the crystal, illustrating the disorder of one cyclo­hexyl group and both THF ligands. Displacement ellipsoids drawn at the 50% probability level and H atoms have been omitted for clarity.
See this image and copyright information in PMC

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