Gas Phase Ion Thermochemistry of Tetraaza Complexes Such as CyclamM2+ with H2O, CH3OH, NH3, and Other Ligands, Where M2+ = Mn2+, Ni
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- 作者：Arthur T. Blades ; Paul Kebarle
- 刊名：Journal of Physical Chemistry A
- 出版年：2006
- 出版时间：November 2, 2006
- 年：2006
- 卷：110
- 期：43
- 页码：12055 - 12062
- 全文大小：118K
- 年卷期：v.110,no.43(November 2, 2006)
- ISSN：1520-5215
文摘
Tetraaza complexes with M2+ were produced in the gas phase by Electrospray (ESI) of solutions containingsalts of M2+dinitrates and a tetraaza compound such as cyclam. The complex CyclM2+ formed in solutionand transferred to the gas phase via ESI was introduced into a reaction chamber containing known partialpressures of a ligand L. Equilibria between CyclM2+ and L establish CyclMLn2+ = CyclMLn-12+ + L andthe equilibrium constants Kn,n-1 are determined with a mass spectrometer. Determinations at differenttemperatures lead to not only the 
G0n,n-1 values but also the H0n,n-1 and S0n,n-1 values. Data for n = 1,2, and 3 were obtained for L = H2O and CH3OH. The G01,0, H01,0 as well as G02,1, H02,1 values, whenM2+ = Mn2+ and Zn2+, were larger than those for Ni2+ and Cu2+. The ligand field theory and the Irvine-Williams series predict a reverse order, i.e., stronger bonding with Ni2+ and Cu2+ for simple ligand reactionswith M2+. An examination of the differences of the reactions in solution and gas phase provides a rationalefor the observed reverse order for the CyclM2+ + L reactions. Differences between gas phase and solutionare found also when M2+ = Cu2+, but the tetraaza macrocycle is changed from, 12-ane to 14-ane to 15-ane.The strongest bonding in solution is with the 14-ane while in the gas phase it is with the 15-ane. Bond freeenergies, G01,0, for CyclCu2+ with L = H2O, CH3OH, NH3, C2H5OH, C3H7OH, (C2H5)2O, and CH3COCH3,are found to increase in the above order. The order and magnitude of the G01,0 values is close to G01,0values observed with potassium K+ and the same ligands. These results show that the cyclam in CyclCu2+leads to an extensive shielding of the +2 charge of Cu2+. Ligands with gas phase basicities that are relativelyhigh, lead to deprotonation of CyclM2+. The deprotonation varies with the nature of M2+ and providesinformation on the extent of electron transfer from the N atoms of the cyclam, to the M2+ ions.
G0n,n-1 values but also the H0n,n-1 and S0n,n-1 values. Data for n = 1,2, and 3 were obtained for L = H2O and CH3OH. The G01,0, H01,0 as well as G02,1, H02,1 values, whenM2+ = Mn2+ and Zn2+, were larger than those for Ni2+ and Cu2+. The ligand field theory and the Irvine-Williams series predict a reverse order, i.e., stronger bonding with Ni2+ and Cu2+ for simple ligand reactionswith M2+. An examination of the differences of the reactions in solution and gas phase provides a rationalefor the observed reverse order for the CyclM2+ + L reactions. Differences between gas phase and solutionare found also when M2+ = Cu2+, but the tetraaza macrocycle is changed from, 12-ane to 14-ane to 15-ane.The strongest bonding in solution is with the 14-ane while in the gas phase it is with the 15-ane. Bond freeenergies, G01,0, for CyclCu2+ with L = H2O, CH3OH, NH3, C2H5OH, C3H7OH, (C2H5)2O, and CH3COCH3,are found to increase in the above order. The order and magnitude of the G01,0 values is close to G01,0values observed with potassium K+ and the same ligands. These results show that the cyclam in CyclCu2+leads to an extensive shielding of the +2 charge of Cu2+. Ligands with gas phase basicities that are relativelyhigh, lead to deprotonation of CyclM2+. The deprotonation varies with the nature of M2+ and providesinformation on the extent of electron transfer from the N atoms of the cyclam, to the M2+ ions.