Electrospray Ionization Tandem Mass Spectrometric Study of Selected Phosphine-Based Ligands for Catalytically Active Organometallics.

Selected organometallic compounds are nowadays extensively used as highly efficient catalysts in organic synthesis. A great variety of different ligand systems exists, of which phosphine-based ligands are a significant subgroup. While mass spectrometry, predominantly electrospray ionization mass spectrometry (ESI-MS), is a standard analytical technique for the identification of new ligands and their metal complexes, there is little information on the behavior of phosphine-based ligands/molecules by electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) at low collision energies (<100 eV) in the literature.

Synthesis and characterization of cobalt SCS pincer complexes.

Unlabelled: The synthesis and characterization of two Co(II) complexes stabilized by a tridentate SCS pincer ligand are described. Paramagnetic [Co(κ-SCS-Et)] and [Co(κ-SCS-Bu)(κ-SCS-Bu)] were obtained via transmetalation protocol from CoBr and S(C-Br)S-R (R = Et, Bu). Oxidation of the latter with [CpFe]PF affords the diamagnetic 18 VE complex [Co(κ-SCS-Bu)]PF.

Characterization of selected organometallic compounds by electrospray ionization- and matrix-assisted laser desorption/ionization-mass spectrometry using different types of instruments: Possibilities and limitations.

Rationale: Organometallic compounds are becoming increasingly important in their industrial application as catalysts. Mass spectrometry is an essential tool for the structural confirmation of such organometallics. Because the analysis of this class of molecules can be challenging, the ionization behavior and structural confirmation of selected transition metal catalysts are described in this work.

-Selective Manganese-Catalyzed Semihydrogenation of Alkynes with H Directly Employed or In Situ-Generated.

Selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst -[Mn(dippe)(CO)(CHCHCH)] (dippe = 1,2-bis(di--propylphosphino)ethane) as a precatalyst is described. The required hydrogen gas is either directly employed or in situ-generated upon alcoholysis of KBH with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl, and terminal alkynes was readily hydrogenated to yield alkenes in good to excellent isolated yields.

Synthesis and Catalytic Reactivity of Cobalt Pincer Nitrosyl Hydride Complexes.

The synthesis, characterization, and catalytic activity of low-spin {CoNO} pincer complexes of the type [Co(PCP)(NO)(H)] are described. These compounds are obtained either by reacting [Co(PCP)(κ-BH)] with NO and EtN or, alternatively, by reacting [Co(PCP)(NO)] with boranes, such as NH·BH in solution. The five-coordinate, diamagnetic Co(III) complex [Co(PCP-Pr)(NO)(H)] was found to be the active species in the hydroboration of alkenes with anti-Markovnikov selectivity.