Pentacoordinate and Hexacoordinate Mn(III) Complexes of Tetradentate Schiff-Base Ligands Containing Tetracyanidoplatinate(II) Bridges and Revealing Uniaxial Magnetic Anisotropy

摘要

Crystal structures and magnetic properties of polymeric and trinuclear heterobimetallic Mn-III center dot center dot center dot Pt-III center dot center dot center dot Mn-III coordination compounds, prepared from the Ba[Pt(CN)(4)] and [Mn(L4A/B)(C1)] (1a/b) precursor complexes, are reported. The polymeric complex [{Mn(L4A)}(2){mu(4)-Pt(CN)(4)](n) (2a), where H(2)L4A = N,N'-ethylene-bis(salicylideneiminate), comprises the {Mn(L4A)} moieties covalently connected through the [Pt(CN)4]2 bridges, thus forming a square-grid polymeric structure with the hexacoordinate Mnill atoms. The trinuclear complex [{Mn(L4B)}2{mu-Pt(CN)(4)] (2b), where H(2)L4B = N,N'-benzene-bis(4-aminodiethylene-salicylideneiminate), consists of two [{Mn(L4B)} moieties, involving pentacoordinate Mnill atoms, bridged through the tetracyanidoplatinate (II) bridges to which they are coordinated in a trans fashion. Both complexes possess uniaxial type of magnetic anisotropy, with D (the axial parameter of zero-field splitting) = 3.7(1) in 2a and -2.2(1) cm(-1) in 2b. Furthermore, the parameters of magnetic anisotropy 2a and 2b were also thoroughly studied by theoretical complete active space self-consistent field (CASSCF) methods, which revealed that the former is much more sensitive to the ligand field strength of the axial ligands.