Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes.

Electrospray-ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2 ZrMe2 ], [Cp2 ZrMe(Cl)], and [Cp2 ZrCl2 ] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion-pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios.

External-stimuli responsive photophysics and liquid crystal properties of self-assembled "phosphole-lipids".

A series of new amphiphilic phosphonium materials that combine the electronic features of phospholes with self-assembly features of lipids were synthesized. Variable concentration/temperature and 2D NMR studies suggested that the systems undergo intramolecular conformation changes between a "closed" and "open" form that are triggered by intermolecular interactions. The amphiphilic features of the phospholium species also induce liquid crystalline and soft crystal phase behavior in the solid state, which was studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable temperature powder X-ray diffraction (VT-PXRD).

Unraveling the roles of the acid medium, experimental probes, and terminal oxidant, (NH4)2[Ce(NO3)6], in the study of a homogeneous water oxidation catalyst.

The oxidation of water catalyzed by [Ru(tpy)(bpy)(OH(2))](ClO(4))(2) (1; tpy = 2,2';6'',2''-terpyridine; bpy = 2,2'-bipyridine) is evaluated in different acidic media at variable oxidant concentrations. The observed rate of dioxygen evolution catalyzed by 1 is found to be highly dependent on pH and the identity of the acid; e.g.

Direct observation of key intermediates by negative-ion electrospray ionisation mass spectrometry in palladium-catalysed cross-coupling.

Negative-ion electrospray ionisation mass spectrometry with an anionic phosphine ligand enables detection of key intermediates in the Sonogashira reaction. MS/MS techniques are used to generate a Hammett plot for the key reductive elimination step.

Insight into water oxidation by mononuclear polypyridyl Ru catalysts.

A family of compounds based on the mononuclear coordination complex [Ru(tpy)(bpy)(OH(2))](2+) (1b; tpy = 2,2':6',2''-terpyridine, bpy = 2,2'-bipyridine) are shown to be competent catalysts in the Ce(IV)-driven oxidation of water in acidic media. The systematic installation of electron-withdrawing (e.g.

Gas-phase reactivity of ruthenium carbonyl cluster anions.

Partially-ligated anionic ruthenium carbonyl clusters react with alkenes, arenes, and alkanes in the gas phase; the products undergo extensive C-H activation and lose dihydrogen and carbon monoxide under collision-induced dissociation conditions. Triethylsilane and phenylsilane are also reactive towards the unsaturated clusters, and oxygen was shown to rapidly break down the cluster core by oxidative cleavage of the metal-metal bonds. These qualitative gas-phase reactivity studies were conducted using an easily-installed and inexpensive modification of a commercial electrospray ionization mass spectrometer.

Ionic liquids enable electrospray ionisation mass spectrometry in hexane.

Addition of a lipophilic ionic liquid to non-polar, hydrocarbon solvents (such as hexane and toluene) permits electrospray ionisation mass spectrometric analysis of dissolved analytes.