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Issue 29, 2010
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Samarium complexes of a σ-/π-pyrrolide/arene based macrocyclic ligand

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A bis-pyrrolide macrocyclic ligand [L = trans-calix[2]benzene[2]pyrrole(H)] containing two aromatic phenyl rings in the macrocycle backbone was reacted with SmCl3(THF)3 to afford the corresponding [LSmIIICl] (1) complex. Its crystal structure showed the ligand adopting the σ-bonding mode with the pyrrolide moieties and the π-bonding with the two aromatic rings. Reaction of 1 with MeLi in THF gave a mixture of two compounds. The major was a C–H activated complex [LSmIII(THF)] (2a) where the bonding mode of the pyrrolide rings was switched from σ- to π- as a result of the deprotonation and metallation of one of the two aromatic rings. The minor component was an unusual [(L)SmIII(HL′)] (2b) complex containing both a regular ligand and an “N-confused” macrocyclic ligand. The two ligands wrapped the Sm center with the regular ligand adopting a bonding mode similar to 1. The second ligand instead acted as a simple σ-bonded monodentate ligand, only using one nitrogen atom of one pyrrolide ring. However, this particular pyrrolide moiety has been isomerized by shifting the ring attachment to the macrocycle (N-confused system). In addition, the second pyrrolide ring has been protonated at the nitrogen atom. Complex 2b was obtained as major compound and in analytically pure form by reacting 1 with NaH.

Graphical abstract: Samarium complexes of a σ-/π-pyrrolide/arene based macrocyclic ligand

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Supplementary files

Article information

04 Feb 2010
28 Apr 2010
First published
21 May 2010

Dalton Trans., 2010,39, 6853-6857
Article type

Samarium complexes of a σ-/π-pyrrolide/arene based macrocyclic ligand

S. Ilango, B. Vidjayacoumar and S. Gambarotta, Dalton Trans., 2010, 39, 6853
DOI: 10.1039/C002514N

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