Novel Cu<sup>II</sup>–M<sup>II</sup>–Cu<sup>II</sup>(M = Cu or Ni) trinuclear and [NaI2CuII6] hexanuclear complexes assembled by bi-compartmental ligands: syntheses, structures, magnetic and catalytic studies
Abstract
In the present work, two compartmental ligands H2L(1) and H2L(2) were in situ generated during the syntheses of new trinuclear complexes, [Cu2Ni(L(1))(2,2'-bpy)2(NO3)2][ClO4]2 (), [Cu3(L(2))(NO3)2][ClO4]2 (), and [Cu3(L(2))(NCS)2(NO3)](+) that co-crystallize in with a [Cu6(L(2))2Na2(NO3)6(NCS)4] unit to give the final molecular formula [Cu6(L(2))2Na2(NO3)6(NCS)4][Cu3(L(2))(NCS)2(NO3)]2(NO3)2·5H2O (). The magnetic property studies of revealed weak Cu(II)-Cu(II) ferromagnetic interactions in compound (JCu-Cu/kB = +1.4(1) K) and (JCu-Cu/kB = +1.6) while in intranuclear Cu(II)-Ni(II)-Cu(II) compound , the magnetic coupling between two Cu(II) ions is switched off by the diamagnetic square planar Ni(II) bridge. The catalytic epoxidation of two olefins, namely styrene and cyclooctene, by tert-BuOOH (TBHP) was also explored in the presence of a catalytic amount of , or in MeCN. For styrene oxidation, exhibited ∼57% styrene epoxide selectively (conversion ∼37%) with a TON of about 925 along with benzaldehyde (∼43%), whereas exhibited conversion up to ∼63% (TON ∼ 1575) with a good selectivity towards epoxide (∼71%). For compound , this conversion is more important (TON ∼ 8108) probably due to the presence of more active sites involved in the epoxidation. The concerted path was found to be operative for styrene oxidation while a radical path was suggested for the oxidation of cyclooctene.