Assembling Bi-, Tri- and Pentanuclear Complexes into Extended Structures Using a Desolvation Reaction:  Synthesis, Structure, and Magnetic Properties of Manganese(III)−Schiff-Base−Hexacyanoferrate Polymeric Compounds and Their Derived Extended Structures

Abstract

[Mn(BS)(H 2 O)]ClO 4 and [NEt 4 ] 3 [Fe(CN) 6 ] react in methanol or ethanol to give a binuclear [NEt 4 ] 2 [{Mn(BS)(S)}{Fe(CN) 6 }], 1, three trinuclear [NEt 4 ][{Mn(BS)(S)} 2 {Fe(CN) 6 }], 2 − 4, and a pentanuclear [Mn(BS)(S)] 4 [Fe(CN) 6 ]ClO 4, 5, heterometal complex, depending on the nature of the quadridentate Schiff-base ligands and regardless of the stoichiometric ratio of the precursor components (BS = saldmen = N, N ‘-(1,1-dimethylethylene)bis(salicylideneiminato) dianion, S = H 2 O for 1; BS = rac -salmen = rac - N, N ‘-(1-methylethylene)bis(salicylideneiminato) dianion, S = MeOH for 2; BS = rac -salcy = rac - N, N ‘-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion, S = MeOH for 3; ( R, R )-salcy = ( R, R )- N, N ‘-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion, S = H 2 O for 4; BS = saltmen = N, N ‘-(1,1,2,2-tetramethylethylene)bis(salycylideneiminato) dianion, S = H 2 O for 5 ). Complexes 1 and 2 have been characterized by X-ray analyses. Complex 1 consists of a discrete CN-bridged Mn(III)−Fe(III) binuclear unit [(H 2 O)Mn(saldmen)Fe(CN) 6 ] 2 - hydrogen-bonded into a one-dimensional chain structure. Complex 2 consists of a discrete centrosymmetric trinuclear unit [(MeOH)Mn(salmen)Fe(CN) 6 Mn(salmen)(MeOH)] - hydrogen-bonded, thus forming a two-dimensional network with a repeating cyclic octamer [−NC−Fe−CN−Mn−MeOH−] 4 unit. Complexes 1 − 5 led to desolvated forms 1 ‘− 5 ‘. Some of these forms ( 1 ‘− 3 ‘) show spontaneous magnetization according to an extended structure where the original magnetically isolated oligomeric forms now communicate with each other. In the case of 4 ‘ and 5 ‘, the desolvation probably occurs with a severe reorganization of the parent hydrogen-bonded extended structure, and hence, cooperative magnetic effects were not observed.