Trinuclear heterometallic Cu^II–Mn^IIcomplexes of a salen type Schiff base ligand: anion dependent variation of phenoxido bridging angles and magnetic coupling

Abstract

Five new trinuclear heterometallic Cu(II)-Mn(II) complexes [(CuL)2Mn(O2CPh)2] (1), [(CuL)2Mn(N3)2] (2), [(CuL)2Mn(NCO)2] (3), [(CuL)2Mn(NO3)2] (4) and [(CuL)2Mn(Sal)2]·CH2Cl2 (5) have been synthesized with the di-Schiff base ligand H2L (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine and Sal = salicylate). These complexes with different anionic co-ligands have been synthesized to attain a large variation in phenoxido bridging angles and to investigate its consequence on magnetic properties. Single crystal X-ray diffraction analyses reveal that complexes 1, 2, 4 and 5 are linear, whereas 3 has an angular geometry. Variable temperature magnetic susceptibility measurements suggest that all five complexes possess an overall antiferromagnetic interaction between Cu(II) and Mn(II) ions, which results in a final ferrimagnetic ground state with spin 3/2 in the Cu(II)-Mn(II)-Cu(II) trinuclear structure. The weakest antiferromagnetic interaction (J(Cu-Mn) = -7.0 cm(-1)) is observed for 2 having the lowest value of the Cu-O-Mn angle (92.0°), while the strongest antiferromagnetic interaction (J(Cu-Mn) = -26.5 cm(-1)) is observed for 3 having the largest Cu-O-Mn angle (101.4°). Complexes 1, 4 and 5 show average Cu-O-Mn angles of 98.2°, 97.6° and 97.7°, respectively, that lead to intermediate antiferromagnetic interactions (J(Cu-Mn) = -9.6, -9.7, -9.3 cm(-1) respectively).

The Impact of Anion‐Modulated Structural Variations on the Magnetic Coupling in Trinuclear Heterometallic CuII–CoII Complexes Derived from a Salen‐Type Schiff Base Ligand

“…Previously, we have synthesized several trinuclear complexes with [CuL] as a metalloligand and diamagnetic Na I , Pb II , Zn II , Cd II , and Hg II or paramagnetic Ni II , Mn II , and Tb III central metal ions 6,8a,12. In the present study, we have prepared three trinuclear complexes by reactions between [CuL], Co(ClO 4 ) 2 · 6H 2 O, and the anionic coligands thiocyanate (SCN – ), benzoate (PhCOO – ), and azide (N 3 – ) in methanol (Scheme ).…”

Crystallization, Structure Determination and Reticular Twinning in Iron(III) Salicylate: Fe[(HSal)(Sal)(H2O)2]

“…Metal complexes of the mono-anionic ligand HSal − are well known from the literature. For recent examples of transition metal complexes, see [22][23][24][25]. In the majority of cases, the hydroxyl group is protonated and the carboxylate group deprotonated.…”

Synthesis of Hetero- and Homo-multinuclear Complexes with a Tetracyanonickelate Anion: Structural Characterization [Cu(bcen)Ni(CN)4]2

“…The τ 4 parameter is [360° -(α + β)]/141°, where α and β are the largest angles around the central metal in the complex; τ 4 = 1 for a regular tetrahedron and τ 4 = 0 for a regular square planar geometry. 38 Each [Ni(CN) 4 ] 2-group coordinates to two Cu(II) ions using two cis-cyanide ligands. Each Cu(bcen) unit is connected to two [Ni(CN) 4 ]…”