Reduction from copper(II) to copper(I) upon collisional activation of (pyridine)₂CuCl⁺

Abstract

Electrospray ionization of dilute aqueous solutions of copper(II) chloride-containing traces of pyridine (py) as well as ammonia permits the generation of the gaseous ions (py)(2) Cu(+) and (py)(2) CuCl(+) , of which the latter is a formal copper(II) compound, whereas the former contains copper(I). Collision-induced dissociation of the mass-selected ions in an ion-trap mass spectrometer (IT-MS) leads to a loss of pyridine from (py)(2) Cu(+) , whereas an expulsion of atomic chlorine largely prevails for (py)(2) CuCl(+) . Theoretical studies using density functional theory predict a bond dissociation energy (BDE) of BDE[(py)(2) Cu(+) -Cl] = 125 kJ mol(-1) , whereas the pyridine ligand is bound significantly stronger, i.e. BDE[(py)CuCl(+) -py] = 194 kJ mol(-1) and BDE[(py)Cu(+) -py] = 242 kJ mol(-1) . The results are discussed with regard to the influence of the solvation on the stability of the Cu(I) /Cu(II) redox couple.

May interstellar leucine react with NO radicals present in interstellar/interplanetary medium? An ion-trap mass spectrometry study

“…A method has been proposed [33,34] and used [35][36][37] to estimate the enthalpies of fragmentations from these curves. To this end, it was suggested to consider the phenomenological appearance energy AEs (AEexp), i.e.…”

Rapid differentiation ofortho-,meta-, andpara-isomers of halogenated phenylmethylidene hydrazinecarbodithioates by metal complexation and electrospray ionization mass spectrometry

“…The collision‐induced dissociation (CID)‐MS experiments were performed by application of an excitation AC voltage to the end caps of the ion trap to induce collisions of the isolated ions (isolation width at 1.2 u) for a period of 30 ms and variable excitation amplitudes. Note that the software of the Finnigan ion trap applies a ‘normalized collision energy’ (see Finnigan Product Support Bulletin 104) by which the mass of the target ion is automatically considered in the calculation of the excitation amplitude in the CID experiments . Data acquisition and analysis were performed using the Xcalibur software package (version 2.0 SR1).…”

Clustering of palladium(II) chloride in acetonitrile solution investigated by electrospray mass spectrometry

“…The abundances of the various palladium-containing clusters given in the diagrams below refer to the integrated isotope envelopes after correction for the baseline as well as signals of the pure solvent. Low-energy CID was performed by application of an excitation AC voltage to the end caps of the ion trap to induce collisions of the mass-selected ions with the helium buffer gas for a period of 20 ms at a trapping parameter of q z = 0.25 [35][36][37]. For all mass spectra 200 scans were averaged with the XCalibur software.…”

“…The large amount of clustering in both positive and negative ion mode together with the low total ion currents compared to other metal(II) salts [20,23,25,26,28,31,32,36] or palladium complexes with larger ligands [27,44,45] suggests a significant amount of aggregation of PdCl 2 in acetonitrile solution. Provided these aggregates were comprising larger numbers of palladium atoms, the ESI mass spectra would always sample only the fractional amount of smaller clusters, either present in solution or formed in the ESI process itself, despite the fact that we applied relatively soft ionization conditions.…”