Oxygen atom transfer, coupled electron-proton transfer, and correlated electron-nucleophile transfer reactions of oxomolybdenum(IV) and dioxomolybdenum(VI) complexes
- Univ. of Melbourne, Victoria (Australia)
The oxo-Mo(IV) complexes LMoO(S{sub 2}PR{sub 2}-S,S{prime}) [L = hydrotris(3,5-dimethylpyrazol-1-yl)boreate; R = Me, Et, Pr{sup i}, Ph] were prepared by reacting MoO(S{sub 2}PR{sub 2}){sub 2} and KL in refluxing toluene. The dioxo-Mo(VI) complexes cis-LMoO{sub 2}(S{sub 2}PR{sub 2}-S) (R = Pr{sup i}, Ph) were prepared by oxidation of the oxo-Mo(IV) complexes or by reaction of LmoO{sub 2}Cl with NaS{sub 2}PR{sub 2}. Oxygen atom transfers from Me{sub 2}SO to LMoO(S{sub 2}Pr{sub 2}) were first-order with respect to Me{sub 2}SO and complex; the overall second-order rate constants at 40{degrees}c range from 9.0(1) x 10{sup -5} M{sup -1}{center_dot}s{sup -1} for LMoO(S{sub 2}PMe{sub 2}) to 2.08(4) x 10{sup -4} M{sup -1}{center_dot}s{sup -1} for LMoO(S{sub 2}PPr{sub 2}); activation parameters were in the ranges of {Delta}H{double_dagger} = 63(1) to 73(1) kJ{center_dot}mol{sup -1}, {Delta}S{double_dagger} = -88(1) to -111(1) J{center_dot}K{sup -1}{center_dot}mol{sup -1}, and {Delta}G{double_dagger} = 100(2) kJ{center_dot}mol{sup -1} for LMoO(S{sub 2}-PMe{sub 2}) to 98(2) kJ{center_dot}mol{sup -1} for LMoO(S{sub 2}PPr{sub 2}). Oxygen atom transfer from pyridine N-oxide to LMoO(S{sub 2}PPr{sub 2}) was also second-order with a rate constant of 1.54(5) x 10{sup -3} M{sup -1}{center_dot}s{sup -1} at 40{degrees}C, {Delta}H{double_dagger} = 62(1) kJ{center_dot}mol{sup -1}, {Delta}S{double_dagger} = -90(1) J{center_dot}K{sup -1}{center_dot}mol{sup -1}, and {Delta}G{double_dagger} = 90(1) kJ{center_dot}mol{sup -1}. The second-order rate laws and large negative entropies of activation are consistent with associative mechanisms for the above reactions.
- OSTI ID:
- 258385
- Journal Information:
- Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 4 Vol. 35; ISSN 0020-1669; ISSN INOCAJ
- Country of Publication:
- United States
- Language:
- English
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