N-Heterocyclic carbene complexes of silver, rhodium and iron: structures, dynamics and catalysis

Brucka, Marta Anna (2012) N-Heterocyclic carbene complexes of silver, rhodium and iron: structures, dynamics and catalysis. [Laurea magistrale], Università di Bologna, Corso di Studio in Advanced spectroscopy in chemistry [LM-DM270]
Documenti full-text disponibili:
Documento PDF
Download (11MB) | Anteprima


The research performed in the framework of this Master Thesis has been directly inspired by the recent work of an organometallic research group led by Professor Maria Cristina Cassani on a topic related to the structures, dynamics and catalytic activity of N-heterocyclic carbene-amide rhodium(I) complexes1. A series of [BocNHCH2CH2ImR]X (R = Me, X = I, 1a’; R = Bz, X = Br, 1b’; R = trityl, X = Cl, 1c’) amide-functionalized imidazolium salts bearing increasingly bulky N-alkyl substituents were synthetized and characterized. Subsequently, these organic precursors were employed in the synthesis of silver(I) complexes as intermediate compounds on a way to rhodium(I) complexes [Rh(NBD)X(NHC)] (NHC = 1-(2-NHBoc-ethyl)-3-R-imidazolin-2-ylidene; X = Cl, R = Me (3a’), R = Bz (3b’), R = trityl (3c’); X = I, R = Me (4a’)). VT NMR studies of these complexes revealed a restricted rotation barriers about the metal-carbene bond. However, while the rotation barriers calculated for the complexes in which R = Me, Bz (3a’,b’ and 4a) matched the experimental values, this was not true in the trityl case 3c’, where the experimental value was very similar to that obtained for compound 3b’ and much smaller with respect to the calculated one. In addition, the energy barrier derived for 3c’ from line shape simulation showed a strong dependence on the temperature, while the barriers measured for 3a’,b’ did not show this effect. In view of these results and in order to establish the reasons for the previously found inconsistency between calculated and experimental thermodynamic data, the first objective of this master thesis was the preparation of a series of rhodium(I) complexes [Rh(NBD)X(NHC)] (NHC = 1-benzyl-3-R-imidazolin-2-ylidene; X = Cl, R = Me, Bz, trityl, tBu), containing the benzyl substituent as a chiral probe, followed by full characterization. The second objective of this work was to investigate the catalytic activity of the new rhodium compounds in the hydrosilylation of terminal alkynes for comparison purposes with the reported complexes. Another purpose of this work was to employ the prepared N-heterocyclic ligands in the synthesis of iron(II)-NHC complexes.

Tipologia del documento
Tesi di laurea (Laurea magistrale)
Autore della tesi
Brucka, Marta Anna
Relatore della tesi
Correlatore della tesi
Corso di studio
Ordinamento Cds
Parole chiave
N-heterocyclic carbenes; silver, rhodium and iron organometallic complexes; catalysis; NMR spectroscopy; DFT calculations.
Data di discussione della Tesi
16 Luglio 2012

Altri metadati

Statistica sui download

Gestione del documento: Visualizza il documento