Energy-Resolved Collision-Induced Dissociation Studies of 1,10-Phenanthroline Complexes of the Late First-Row Divalent Transition Metal Cations: Determination of the Third Sequential Binding Energies

Abstract

The third sequential binding energies of the late first-row divalent transition metal cations to 1,10-phenanthroline (Phen) are determined by energy-resolved collision-induced dissociation (CID) techniques using a guided ion beam tandem mass spectrometer. Five late first-row transition metal cations in their +2 oxidation states are examined including: Fe(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+). The kinetic energy dependent CID cross sections for loss of an intact Phen ligand from the M(2+)(Phen)3 complexes are modeled to obtain 0 and 298 K bond dissociation energies (BDEs) after accounting for the effects of the internal energy of the complexes, multiple ion-neutral collisions, and unimolecular decay rates. Electronic structure theory calculations at the B3LYP, BHandHLYP, and M06 levels of theory are employed to determine the structures and theoretical estimates for the first, second, and third sequential BDEs of the M(2+)(Phen)x complexes. B3LYP was found to deliver results that are most consistent with the measured values. Periodic trends in the binding of these complexes are examined and compared to the analogous complexes to the late first-row monovalent transition metal cations, Co(+), Ni(+), Cu(+), and Zn(+), previously investigated.

Disassembly Mechanisms and Energetics of Polymetallic Rings and Rotaxanes with Ion Mobility Mass Spectrometry

“…15 The lability of [RingCu]is a result of Jahn-Teller distortions causing the elongation of one of the F-Cu II -O axes, 16 which is well-known from other Cu II complexes and its impact on periodic trends previously reported. 17,18 Jahn-Teller effects could also make [RingCu]more flexible, as observed before for related structures containing five-coordinate Cu II sites. 19 Notably, our data agree well with the M II trend for water-exchange reaction rate constants of the hexaaqua ions [M II (H2O)6] 2+ (Table S5, Figure S32), although a different stability trend from ESI-MS experiments has recently been reported for supramolecular terpyridine-based complexes (Ni II > Co II > Zn II > Fe II > Cu II > Cd II > Mn II ), indicating that the electronic environment of M II may be altered in the case of some ligands.…”

Cationic Noncovalent Interactions: Energetics and Periodic Trends

“…Trends in these values are comparable to those for the ligands discussed above. In addition, TCID methods have been used to measure the (Phen) 2 M 2+ –Phen BDE, where Phen = phenanthroline for M = Fe 2+ (211 ± 11 kJ/mol), Co 2+ (204 ± 12 kJ/mol), Ni 2+ (213 ± 13 kJ/mol), Cu 2+ (160 ± 10 kJ/mol), and Zn 2+ (170 ± 14 kJ/mol) . Here the value for Fe 2+ (Phen) 3 is obtained assuming dissociation comes from an excited quintet state of the Fe 2+ (Phen) 3 complex.…”

“…Trends in these values are comparable to those for the ligands discussed above. In addition, TCID methods have been used to measure 251 Here the value for Fe 2+ (Phen) 3 is obtained assuming dissociation comes from an excited quintet state of the Fe 2+ (Phen) 3 complex. If the singlet ground state is assumed, the BDE is 236 ± 17 kJ/mol, which does not agree well with theory.…”

Base-Pairing Energies of Proton-Bound Dimers and Proton Affinities of 1-Methyl-5-Halocytosines: Implications for the Effects of Halogenation on the Stability of the DNAi-Motif

“…The threshold regions of the measured CID cross-sections are modeled using procedures developed elsewhere [55][56][57][58][59][60][61][62] that have been found to reproduce CID cross-sections well [63][64][65][66][67]. Details regarding data handling and analysis procedures, which includes explicitly accounting for the internal and translational energy distributions of the reactant proton-bound dimers, the effects of multiple ion-neutral collisions, and the lifetime of the dissociating proton-bound dimers, are summarized in the Supplementary Information.…”