Thermochemistry and Photodissociation Studies of [CoL]+ and [CoL2]+, L=Pyrrole, Furan, Thiophene and Selenophene

✍ Scribed by Nanayakkara, Vajira K.; Freiser, Ben S.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 463 KB
• Volume: 32
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199705)32:5<475::aid-jms489>3.0.co;2-p

✦ Synopsis

CoL ] ' and (L = pyrrole, furan, thiophene and selenophene) were generated in a prototype Nicolet-[ CoL 2 ] ' 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-o † Ðlters, yielded the bond energies D0(Co'wpyrrole) = 59 » 3 kcal mol-1, D0(Co'wfuran) = 57 » 3 kcal mol-1, D0(Co'wthiophene) = 61 » 3 kcal mol-1 and D0(Co'wselenophene) = 64 » 3 kcal mol-1 (1 kcal = 4.184 kJ), as well as D0( [ Co(pyrrole) ] 'wpyrrole) O 48 » 3 kcal mol-1, D0([Co(furan) ] 'wfuran) O 46 » 3 kcal mol-1, D0( [ Co(thiophene) ] 'wthiophene) O 49 » 3 kcal mol-1 and D0( [ Co(selenophene) ] 'wselenophene) O 51 » 3 kcal mol-1.

The photoappearance threshold for the CO loss product ion from [ Co(furan) ] ', yielded [ CoC 3 H 4 ] ', 33 » 6 or 32 » 6 kcal mol-1, depending on whether was allene or propyne, D0(Co'wC 3 H 4 ) = either C 3 H 4 respectively. Where possible, these bond energy measurements were further corroborated by ligand displacement reactions and competitive collision-induced dissociation experiments.