51306-09-3Relevant articles and documents
Thermodynamic stabilities of Cu+ and Li+ complexes of dimethoxyalkanes (MeO(CH2)nOMe, n = 2-9) in the gas phase: Conformational requirements for binding interactions between metal ions and ligands
Mishima, Masaaki,Maeda, Hideyuki,Than, Soe,Irie, Maki,Kikukawa, Kiyoshi
, p. 616 - 623 (2007/10/03)
The relative free energy changes for the reaction ML+ = M + + L (M = Cu+ and Li+) were determined in the gas phase for a series of dimethoxyalkanes (MeO(CH2)nOMe, n = 2-9) by measuring the equilibrium constants of ligand-transfer reactions using a FT-ICR mass spectrometry. Stable 1:1 Cu+-complexes (CuL +) were observed when the chain is longer than n = 4 while the 1:2 complexes (CuL2+) were formed for smaller compounds as stable ions. The dissociation free energy for CuL+ significantly increases with increasing chain length, by 10 kcal mol-1 from n = 4 to 9. This increase is attributed to the release of constrain involved in the cyclic conformation of the Cu+-complexes. This is consistent with the geometrical and energetic features of the complexes obtained by the DFT calculations at B3LYP/6-311G level of theory. On the contrary, the corresponding dissociation free energy for LiL+ increases only 3 kcal mol -1 from n = 2 to 9, although the structures of the 1:1 Li +-complexes are also considered to be cyclic. From these results it is concluded that the Cu[MeO(CH2)nOMe]+ requires linear alignment for O-Cu-O, indicating the importance of sd σ hybridization of Cu+ in the first two ligands binding energy, while the stability of the Li+ complex is less sensitive to binding geometries except for the system forming a small ring such as n = 1 and 2. Copyright
