The reaction of the carbido cluster anion [Re7C(CO)21]3- with I2, in MeCN, under CO, allows the removal of the Re(CO)3+ capping moiety, affording the octahedral cluster dianion [Re6C(μ-CO)(CO)18]2- almost quantitatively. The anion, characterized by single-crystal X-ray analysis as its [PPh4]+ salt, has an idealized Cs symmetry and consists of a carbon-centred metal octahedron surrounded by 18 terminal (three for each metal atoms) and one doubly bridging carbonyl ligand. The same species is obtained by dissolving the monoanion [Re7C(CO)22]- in MeCN. Variable-temperature 13C NMR spectra indicate that the bridging carbonyl, in solution, is completely delocalized on the cluster edges and interchanges with the terminal carbonyls. The ion [Re6C(μ-CO)(CO)18]2- can be reversibly protonated, affording [Re6(μ-H)C(μ-CO)(CO)18]-, characterized by single-crystal X-ray analysis as its [NEt4]+ salt (CH2Cl2 clathrate). The carbonyl connectivity pattern resembles that of the parent anion, although the presence of the H ligand in a doubly briding location (detected by the atom-pair potential method) lowers the symmetry to C1. The ion [Re6C(μ-CO)(CO)18]2- is also able to react with Group 11 cations, as Ag+, Cu+ or Au(PPh3)+, giving adducts which can be considered intermediate between molecular complexes and ion pairs, on the basis of the ν(CO) frequencies and of the 13C NMR spectrum of the silver derivative.
Synthesis and crystal structures of the carbido cluster anions [re6C(μ-CO)(CO)18]2- and [re6(μ-H)C(μ-CO)(CO)18] / T. Beringhelli, G. D'Alfonso, H. Molinari, A. Sironi. - In: JOURNAL OF THE CHEMICAL SOCIETY DALTON TRANSACTIONS. - ISSN 0300-9246. - :4(1992), pp. 689-695.
|Titolo:||Synthesis and crystal structures of the carbido cluster anions [re6C(μ-CO)(CO)18]2- and [re6(μ-H)C(μ-CO)(CO)18]|
BERINGHELLI, TIZIANA (Primo)
D'ALFONSO, GIUSEPPE (Secondo)
SIRONI, ANGELO AGOSTINO DANIELE (Ultimo)
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||1992|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1039/DT9920000689|
|Appare nelle tipologie:||01 - Articolo su periodico|