GAS-PHASE ION-MOLECULE CHEMISTRY OF TRANSITION METAL COMPLEX NEGATIVE IONS: A FLOWING AFTERGLOW STUDY (ELECTRON TRANSFER, LIGAND SUBSTITUTION, CATALYSIS, ORGANOMETALLIC

Twelve transition metal complex negative ions were generated by either electron attachment or dissociative electron attachment to.;neutral transition metal complexes in a flowing afterglow apparatus. These twelve negative ion complexes were (OC)(,4)Fe('-), (OC)(,5)Cr('-),;(OC)(,4)MnH('-), (OC)Fe(NO)(,2)('-), (OC)(,2)Co(NO)('-), ((eta)('3)-C(,3)H(,5))Co(CO)(,2)('-), ((eta)('1)-C(,3)H(,5))Co(CO)(,3)('-), (eta)('3)-CpCo(CO)(,2)('-), (OC)(,3)Fe('-), and ((eta)('4)-C(,4)H(,6))Fe(CO)(,x)('-).;(x = 1-3). The reactions of the first eight complexes with the series of halomethanes CF(,3)I, CF(,3)Br, CF(,3)Cl, CCl(,4), CCl(,3)Br, CH(,3)I, CH(,3)Br, CH(,3)Cl,;CH(,2)Cl(,2), CHCl(,3), CFCl(,3), and CF(,2)Cl(,2), and the series of ligand substi- tution neutrals PF(,3), P(CH(,3))(,3), NO, SO(,2), O(,2), CH(,3)CN, CF(,3)CH(,2)ONO,;CH(,3)COCH(,3), CH(,3)COCF(,3), CF(,3)COCF(,3), CH(,3)COCOCH(,3), CF(,2)=CF(,2), C(CN)(,2)=C(CN)(,2), CH(,2)=CHCH(,3), CH(,2)=CHCN, CH(,2)=CHCO(,2)CH(,3),;CH(,2)=CHOC(,2)H(,5), CH(,2)=CHBr, CS(,2), CO, and P(OCH(,3))(,3) were investigated.;The major or exclusive product in the reactions of the negative ion transition metal complexes with the various halomethanes was halogen atom transfer (i.e. (OC)(,4)Fe('-) + CCl(,4) (--->) (OC)(,4)FeCl('-) + (.)CCl(,3)).;Correlations between the reactivity of the respective complexes in terms of the bimolecular ion-molecule rate constant (k(,total)) for the halogen atom transfer reactions, and the following three kinetic or thermochemical properties of the halomethanes were attempted; (i) the carbon halogen bond dissociation energy (D(DEGREES)(C-X)), (ii) the electron affinity (EA), and (iii) the thermal electron attachment rate constant k(,TEA). A correlation between k(,total) and k(,TEA) was obtained leading to a proposed electron transfer mechanism in the halogen atom transfer reactions.;The reactions with ligand substitution neutrals occurred primarily with displacement of a carbonyl ligand. Adduct formation in some of the ligand substitution reactions of (OC)Fe(NO)(,2)('-), (OC)(,2)Co(NO)('-), and ((eta)('3)-C(,3)H(,5))Co(CO)(,2)('-) was proposed to occur by a coordination switch of the nitrosyl or allyl ligand from 3-electron to 1-electron donor ligands.;The following thermochemical values were derived from the present study; EA(CpCo(CO)(,2)) (LESSTHEQ) 0.29 eV, EA(((eta)('3)-C(,3)H(,5))Co(CO)(,3)) = 0.62 (+OR-) 0.1 eV, and EA (Mn(CO)(,3)(O)) (TURN) 3.5 eV. In addition, numerous other relative ligand binding energies were determined.;The reactions (OC)(,4)Fe('-) with hydrogen atoms, (OC)(,3)Fe('-) with CO, N(,2), CH(,2)=CHCH(,3), CH(,2)=C=CH(,2), C(,2)H(,2), and CH(,3)Br, and ((eta)('4)-C(,4)H(,6))- Fe(CO)('-) with H(,2) and D(,2) are reported and discussed.