Mass Spectrometry of Metal Complexes of Bis-Quinolizidine Alkaloids: Electron Ionization and Fast Atom Bombardment Mass Spectral Study of Copper(II) (–)-Sparteine and (–)-α-Isosparteine Complexes

Abstract

The electron ionization (EI) and fast atom bombardment (FAB) mass spectral fragmentations of ten copper(II) dichloride (dibromide, diformate, diacetate and dithiocyanate) complexes of (-)-sparteine and (-)-alpha-isosparteine were investigated. Fragmentation pathways, elucidation of which was assisted by accurate mass measurements and metastable transitions (EI-MS), as well as FAB/collision-induced dissociation (CID) mass spectral measurements are discussed. The data obtained create the basis for the differentiation of the ligand (sparteine or alpha-isosparteine) in the investigated complexes. The comparison of the results with those obtained previously for corresponding zinc(II) complexes forms the basis for the differentiation of metals in these compounds. The results show that both EI-MS and FAB-MS are very useful tools for the differentiation of ligands, as well as metals in the series of Zn(II) and Cu(II) dichloride (dibromide, diacetate, diformate, dithioacetate) complexes of (-)-sparteine and (-)-alpha-isosparteine.

JMS Letters

“…Table 2 presents the values of m 1 , m 2 , and m 3 coefficients for compounds 1-6 as : Table 2, the differences between the m 1 -m 3 values of 5 and 6 can be sufficient to distinguish the copper (II) of 2-methylsparteine 6 from the zinc (II) complex of 2-methylsparteine 5. It ought to be pointed out that, as was shown by us earlier, [17] the copper complex 6 have higher values of m 1 , m 2 , and m 3 coefficients than those of the zinc complex 1. Moreover, the zinc complex 2 have lower values of m 2 and m 3 than m 2 and m 3 of copper complex 6.…”

“…[10][11][12][13][14][15] Some effort has been devoted to the electron ionization and fast atom bombardment mass spectral study for differentiation of ligand, as well as metals in the series of Zn +2 and Cu +2 dichloride (dibromide, diacetate, diformate, dithioacetate) complexes of (-)-sparteine and (-)-aisosparteine. [16,17] Several principles are fragmentally used to predict stabilities and binding preferences: the Irving-Williams series [18] and the hard-soft acid-base concept. The Irving-Williams series state the complex stabilities should typically follow their order Co +2 < Ni +2 < Cu +2 > Zn +2 .…”

“…and (-)-a-isosparteine has been previously used in our laboratory. [16,17] Low-resolution and high-resolution mass spectra were recorded using a model 432 two-sector mass spectrometer [AMD-Intectra GmbH D-27243 Harpstedt, Germany] ionizing voltage 70 eV, accelerating voltage 8 kV, mass resolution 10 000 at 10% valley. Samples were introduced by a direct insertion probe at a source temperature of~150 C. The elemental compositions of the ions were determined by peak matching method relative to perfluorokerosene.…”

“…make impossible the determination of atom of metal in the investigated complexes 5 and 6. So, for establishing whether it is possible to differentiate the metal atom based on the comparison of the values of the coefficients m (as it was established by us earlier [17] ), we calculated these coefficients that is, the abundances of selected fragment ions relative to the abundances of the oddelectron fragment ions C 16 H 28 N 2 (m/z 248). Table 2 presents the values of m 1 , m 2 , and m 3 coefficients for compounds 1-6 as : Table 2, the differences between the m 1 -m 3 values of 5 and 6 can be sufficient to distinguish the copper (II) of 2-methylsparteine 6 from the zinc (II) complex of 2-methylsparteine 5.…”

Mass Spectrometry of Bis-Quinolizidine Alkaloids: FAB-MS of Oxo-Substituted Sparteines

“…show antihypertensive, antipyretic, anti-inflammatory, antiarrhythmic, diuretic, hypoglicemic, hypotensive, antidiabetic, respiratory depressant and stimulant, and uterotonic properties [5, 6]. The mass spectrometry study of bis-quinolizidine alkaloids has been stimulated by the evidence of the method's ability to distinguish their stereoisomers, metamers, and positional isomers [7–14]. The main characteristic of the so-called “hard” electron-impact induced ionization (EI) of mass fragmentation of bis-quinolizidine alkaloid molecular ions is the dependence of the fragmentation pathway of the bis-quinolizidine skeleton on the stereochemistry of the A/B and C/D ring junctions.…”