Abstract |
New diamine bis-phenol compounds of salan-(HOPh CHNH(CH2)(2)NHCHPh OH, Ph = 2,4-(CMe2Ph) C6H2, H(2)L1) and salen-type (HOPh CHN(CHPh)(2)NCHPh OH, Ph = 2,4-(BuC6H2)-Bu-t, H2L2 and HOPh CHN(1,1 -2-binaphthyl) NCHPh OH, Ph = 2,4-(BuC6H2)-Bu-t, H(2)L3), as well as their oxido vanadium derivatives are described. VO((OPr)-Pr-i) 3 was used as starting material for the preparation of [VO((OPr)-Pr-i)(L1)], 1, [VO((OPr)-Pr-i)(L2)], 3, and (mu-O)\[VO((OPr)-Pr-i)(m-O)(L-3)VO]\(2), 5. An intramolecular redox process involving the reduction of V(V) to V(IV) converts 3 into [VO(L2)], 4. The reactions of 1 and 5 with Me3SiCl give [VOCl(L1)], 2, and [VOCl(L3)], 6, respectively. All complexes were tested as catalysts for the sulfoxidation of thioanisole using H2O2 as oxidant. In general, the compounds display high activity and selectivity, although salantype complexes (1 and 2) perform better. Comparison of complexes 5 and 6 shows that the monomeric species is more active and selective. Well-defined complexes, 5 and 6, display better catalytic performance than systems using 1:1.5 [VO(acac)(2)] and H(2)L3. (C) 2018 Published by Elsevier B.V. |