Collision induced dissociation (CID) to probe the outer sphere coordination chemistry of bis-salicylaldoximate complexes.

Ligand-ligand interactions in the outer coordination sphere make an important contribution to the effects of 3-substituents on the stabilities of anionic Cu(II) salicylaldoximato complexes [CuL(L-H)](-). When substituents contain a different number of bonds the interpretation of CID tandem mass spectrometry must take into account the ability of ions to redistribute energy acquired in collisions within different numbers of vibrational modes.

Binuclear cobalt complexes of Schiff-base calixpyrroles and their roles in the catalytic reduction of dioxygen.

The syntheses and characterization of a series of binuclear cobalt complexes of the octadentate Schiff-base calixpyrrole ligand L are described. The cobalt(II) complex [Co(2)(L)] was prepared by a transamination method and was found to adopt a wedged, Pac-man geometry in the solid state and in solution. Exposure of this compound to dioxygen resulted in the formation of a 90:10 mixture of the peroxo [Co(2)(O(2))(L)] and superoxo [Co(2)(O(2))(L)](+) complexes in which the peroxo ligand was found to bind in a Pauling mode in the binuclear cleft in pyridine and acetonitrile adducts in the solid state.

Enhanced acidity of Zn2+ in the presence of small numbers of water molecules.

Experiments performed on gas phase [Zn(H2O)N]2+ complexes, for N in the range 4-7, show the ions readily undergo unimolecular (metastable) decay with respect to proton release via the reaction [Zn(H2O)N]2+--> Zn(2+)OH(-)(H2O)M + H3O(+)(H2O)N-M-2. To account for these products, it is proposed that the larger complexes have a stable [Zn(H2O)4]2+ core to which additional molecules are retained in an outer shell through hydrogen bonding. At N = 7, this arrangement would make it possible for proton release to be associated with a chain of up to four water molecules, which equates with ideas proposed for the activity of Zn2+ in metalloenzymes.

Probing the self-assembly of inorganic cluster architectures in solution with cryospray mass spectrometry: growth of polyoxomolybdate clusters and polymers mediated by silver(I) ions.

Cryospray mass spectrometry (CSI-MS) has been used to probe the mechanism of self-assembly of polyoxometalate clusters in solution. By using CSI-MS and electronic absorbance spectroscopy it was possible to monitor in real-time the self-assembly of polymeric chains based on [Ag 2Mo 8O 26] (2-) n building blocks. The role of the Ag (I) ion in the solution state rearrangement of molybdenum Lindqvist ({Mo 6}) into the silver-linked beta-octamolybdate ({Mo 8}) structure (( n-C 4H 9) 4N) 2 n [Ag 2Mo 8O 26] n ( 1) is revealed in unprecedented detail.

The solvation of Mg2+ with gas-phase clusters composed of alcohol molecules.

The dication Mg2+ has been clustered with a range of different alcohols to form [Mg(ROH)N]2+ complexes, where N lies in the range 2-10. Observations on the chemistry of the complexes reveal two separate patterns of behavior: (i) unimolecular metastable decay, where at small values of N the complexes undergo rapid charge separation via Coulomb explosion; and (ii) electron capture-induced decay, where collisional activation promotes bond-breaking processes via charge reduction. For the latter it has been possible to identify a generic set of reactions that are common to all of the different [Mg(ROH)N]2+ complexes; however, there are examples of reactions that are specific to individual alcohols and values of N.

A gas-phase study of the preferential solvation of Mn(2+) in mixed water/methanol clusters.

The kinetic shift that exists between two competing unimolecular fragmentation processes has been used to establish whether or not gas-phase Mn(2+) exhibits preferential solvation when forming mixed clusters with water and methanol. Supported by molecular orbital calculations, these first results for a metal dication demonstrate that Mn(2+) prefers to be solvated by methanol in the primary solvation shell.

The solvation of Cu2+ with gas-phase clusters of water and ammonia.

A detailed study has been undertaken of the gas-phase chemistry of [Cu(H2O)N]2+ and [Cu(NH3)N]2+ complexes. Ion intensity distributions and fragmentation pathways (unimolecular and collision-induced) have been recorded for both complexes out as far as N=20. Unimolecular fragmentation is dominated by Coulomb explosion (separation into two single charged units) on the part of the smaller ions, but switches to neutral molecule loss for N>7.

Gas-phase study of the chemistry and coordination of lead(II) in the presence of oxygen-, nitrogen-, sulfur-, and phosphorus-donating ligands.

Using a pickup technique in association with high-energy electron impact ionization, complexes have been formed in the gas phase between Pb(2+) and a wide range of ligands. The coordinating atoms are oxygen, nitrogen, sulfur, and phosphorus, together with complexes consisting of benzene and argon in association with Pb(2+). Certain ligands are unable to stabilze the metal dication, the most obvious group being water and the lower alcohols, but CS(2) is also unable to form [Pb(CS(2))(N)](2+) complexes.

Fragmentation pathways of [Mg(NH3)n]2+ complexes: electron capture versus charge separation.

New experimental results are presented from a detailed study of gas-phase [Mg(NH(3))(n)](2+) complexes and their fragmentation pathways. The reactions examined range from those observed as metastable (unimolecular) decompositions through to collision-induced processes, which have been accessed using a variety of collision gases. Measurements of ion intensity distributions coupled with unimolecular decay studies show that [Mg(NH(3))(4)](2+) not only is the most intense species detected but also sits at a critical boundary between complexes that are unstable with respect to charge separation and those that are sufficiently solvated to be deemed stable on the time scale of the experiment.