The reactions of the unsaturated cluster anion [Re3(μ-H) 4(CO)10]- (1) with 1,2-, 1,3- and 1,4-diazines (used as solvents) have been investigated. The reaction with 1,2-diazine at room temperature gives quantitatively the anion [Re3(μ-H) 2(μ-η2-N2C4H 4)(CO)10]- (3), containing a diazine bridging through the two N atoms, characterised by single crystal X-ray analysis. The orthometallated isomer [Re3(μ-H)3(μ-η 2-N2C4H3)(CO)10] - (4) was obtained by refluxing 3 in toluene. The reaction of [NEt4]1 in molten 1,4-diazine (60°C) affords the anion [Re 3(μ-H)3(μ-η2-N2C 4H3)(CO)10]- (5), containing orthometallated pyrazine. The slow reaction of [NEt4]1 with 1,3-diazine at room temperature gives two orthometallated isomers 6, corresponding to the metallation of carbon C2 (6a) and C6 (6b), respectively (6b/6a ratio ca. 1.2). Differently from what previously found for the analogous cluster anion containing orthometallated pyridine, the metallation reaction of diazines showed little reversibility, and poor conversion of 5 and 6 to the starting anion 1 was observed after several days under 100 atm of H 2. Competition experiments, performed by dissolving [NEt 4]1 in equimolar mixtures of pyridine/pyrazine or pyridine/pyrimidine, showed that the anion with metallated pyridine was the kinetically preferred product and that at longer times it slowly converted to the derivatives with metallated diazines (5 or 6). © 2003 Elsevier Science B.V. All rights reserved.
Competition studies on the activation of the C-H bond of diazines by the unsaturated triangular cluster anion [Re3(μ-H) 4(CO)10] / T. Beringhelli, G. D'Alfonso, D. Maggioni, M. Panigati, P. Mercandelli, A. Sironi. - In: JOURNAL OF MOLECULAR CATALYSIS. A: CHEMICAL. - ISSN 1381-1169. - 204-205(2003), pp. 361-369.
|Titolo:||Competition studies on the activation of the C-H bond of diazines by the unsaturated triangular cluster anion [Re3(μ-H) 4(CO)10]|
BERINGHELLI, TIZIANA (Primo)
D'ALFONSO, GIUSEPPE (Secondo)
MERCANDELLI, PIERLUIGI (Penultimo)
SIRONI, ANGELO AGOSTINO DANIELE (Ultimo)
|Parole Chiave:||C-H bond activation ; Carbonyl clusters ; Diazines ; Orthometallation ; Rhenium|
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||2003|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/S1381-1169(03)00318-2|
|Appare nelle tipologie:||01 - Articolo su periodico|