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The international journal for inorganic, organometallic and bioinorganic chemistry
Paper
Dalton Trans., 2010, 39, 736 - 748, DOI: 10.1039/b905948b
Sodium complexes containing 2-iminopyrrolyl ligands: the influence of steric hindrance in the formation of coordination polymers
Clara S. B. Gomes, D. Suresh, Pedro T. Gomes, Luis F. Veiros, M. Teresa Duarte, Teresa G. Nunes and M. Conceição Oliveira
Iminopyrrolyl complexes of sodium were prepared from the reaction of 2-arylformiminopyrrole ligand precursors (aryl = C6H5 ( I); 2,6-Me2C6H3 ( II); 2,4,6-Me3C6H2 ( III); 2,6-iPr2C6H3 ( IV)) with one equivalent of sodium hydride. The resulting corresponding compounds 1–4, [{Na(
2:
2N,N
-iminopyrrolyl)}2n(OEt2)2x] (n
1; x = 0 or 1), were obtained in moderate to high yields and were characterised by NMR spectroscopy, high resolution mass spectrometry and X-ray diffraction, when suitable crystals were obtained. The X-ray structure of compound 1 (n
1; x = 0) reveals the formation of a coordination polymer with repeating units consisting of dimers that contain two iminopyrrolyl ligands chelating two sodium atoms, where both pyrrolyl rings exhibit bridging 
+ coordination to the Na atoms within the dimer; the self-assembling of the polymer is established by additional 
-bonds (
5-coordination) of each of the pyrrolyl rings to the sodium atoms of the adjacent dimer units. Conversely, the structure of complex DIV (n = x = 1) shows it as one of such dimers capped by two diethyl ether molecules, each coordinated to the sodium atoms (n = 2; x = 1). DFT calculations indicate that the differences between the structures of 1–4 arise from the increasing bulkiness imposed by the corresponding substituents of the iminic aryl groups.
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