New tricyanoiron(III) building blocks for the construction of molecule-based magnets

Abstract

A series of tricyanoiron(III) complexes with the general formula mer-[Fe III (5-Xsap)(CN) 3 ] 2 (X = H, Me, MeO, Cl or Br, sapH 2 = N-salicylidene-o-aminophenol) have been synthesized. These complexes were characterized by IR, ESI-MS, UV/Vis, elemental analysis and magnetic measurements. The structures of (PPh 4 ) 2 [Fe III (sap)(CN) 3 ] and (PPh 4 ) 2 [Fe III (5-Mesap)(CN) 3 ] have been determined by X-ray crystallography. These low-spin d 5 tricyanoiron(III) complexes are potential building blocks for the construction of molecule-based magnets. cyano, iron, Schiff base, building block, molecule-based magnet

Experimental and Theoretical Investigations of Magnetic Exchange Pathways in Structurally Diverse Iron(III) Schiff-Base Complexes

“…In the case of homoleptic complex anions [FeL 2 ] − , the resultant chromophore {FeN 2 O 4 } is not able to accommodate ligand-field strength to stabilize the low-spin state of the central iron­(III) atom; therefore, such complexes are high spin (HS) ( S = 5/2, 6 A 1g in octahedral geometry). Actually, the only low-spin (LS) Fe­(III) complex involving the L 2– ligand is (PPh 4 ) 2 [FeL­(CN) 3 ] (where PPh 4 + is the tetraphenylphosphonium cation), where the strong ligand field is induced by the cyanido ligands . Other mononuclear and polynuclear heteroleptic complexes are reported as the HS complexes in which the bridging between the Fe­(III) centers is provided by the phenoxy O atoms from the L 2– ligands and the magnetic exchange interactions are reported as antiferromagnetic .…”

“…Actually, the only lowspin (LS) Fe(III) complex involving the L 2− ligand is (PPh 4 ) 2 [FeL(CN) 3 ] (where PPh 4 + is the tetraphenylphosphonium cation), where the strong ligand field is induced by the cyanido ligands. 27 Other mononuclear and polynuclear heteroleptic complexes are reported as the HS complexes in which the bridging between the Fe(III) centers is provided by the phenoxy O atoms from the L 2− ligands and the magnetic exchange interactions are reported as antiferromagnetic. 26c Only very recently, the 3-methoxy-substituted (H 2 3MeO-L) derivative of the H 2 L ligand was used for the preparation of heterobimetallic 3d-4f complexes: tetranuclear Ni 2 Ln 2 , 28 hexanuclear Ni 4 Ln 2 , 29 and trinuclear Fe 2 Ln.…”