FT-ICR studies of polypyrazolyl-1-yl borates of europium(II) adducts

In this work we report the synthesis and characterization of europium(II) h ydrotris(parazol-1-yl)borate complexes, Eu(HBP3)(2)L-2 (L = bis(pentamethyl ene)urea, diphenylphosphineamide, 2-azacyclononanone, 2-azacycloheptanone). The characterization of the complexes was accomplished by Fourier transfor m ion cyclotron resonance mass spectrometry using electrospray ionization. For all the complexes, the Eu(HBPz(3))(2)L-2(+) ion was observed. To evalua te the relative bond strength of the ligand L to europium polypyrazolylbora te, infrared multiphoton dissociation (IRMPD) experiments were performed us ing a 40-W continuous-wave CO2 (lambda =10.46 mum) laser aligned on-axis wi th the ion cloud. The parent ion was dissociated to form the daughter ions, Eu(HBPZ(3))(2)L+ and Eu(HBPz(3))(2)(+). The kinetics for unimolecular diss ociation showed the relative bond strengths of the different adducts of the europium complex to be: dipheaylphosphineamide >2-azacyclononanone approxi mate to2-azacycLoheptanone. Dissociation experiments could not be made for the adduct with bis(pentamethylene)urea due to the weak bond. (C) 2001 Else vier Science B.V. All rights reserved.