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Thermochemistry and Photodissociation Studies of [CoL] + and [CoL 2 ] + , L=Pyrrole, Furan, Thiophene and Selenophene
Author(s) -
Nanayakkara Vajira K.,
Freiser Ben S.
Publication year - 1997
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199705)32:5<475::aid-jms489>3.0.co;2-p
Subject(s) - thiophene , furan , chemistry , pyrrole , allene , photochemistry , photodissociation , bond dissociation energy , propyne , medicinal chemistry , dissociation (chemistry) , organic chemistry , catalysis
[CoL] + and [CoL 2 ] + (L=pyrrole, furan, thiophene and selenophene) were generated in a prototype Nicolet‐FTMS 1000 Fourier transform mass spectrometer, where they were irradiated with light from a 2.5 kW Xe arc lamp. Photodissociation thresholds, obtained using energy cut‐off filters, yielded the bond energies D 0 (Co + −pyrrole)=59±3 kcal mol ‐1 , D 0 (Co + −furan)=57±3 kcal mol ‐1 , D 0 (Co + −thiophene)=61±3 kcal mol ‐1 and D 0 (Co + −selenophene)=64±3 kcal mol ‐1 (1 kcal=4.184 kJ), as well as D 0 ([Co(pyrrole)] + −pyrrole)⩽48±3 kcal mol ‐1 , D 0 ([Co(furan)] + −furan)⩽46±3 kcal mol ‐1 , D 0 ([Co(thiophene)] + −thiophene)⩽49±3 kcal mol ‐1 and D 0 ([Co(selenophene)] + −selenophene)⩽51±3 kcal mol ‐1 . The photoappearance threshold for [CoC 3 H 4 ] + , the CO loss product ion from [Co(furan)] + , yielded D 0 (Co + −C 3 H 4 )=either 33±6 or 32±6 kcal mol ‐1 , depending on whether C 3 H 4 was allene or propyne, respectively. Where possible, these bond energy measurements were further corroborated by ligand displacement reactions and competitive collision‐induced dissociation experiments.