Structure and magnetism of analogous O-bridged (phenolato) and S-bridged (thiophenolato) binuclear copper(II) complexes. Crystal structure of the binuclear S-bridged complex µ-[2,6-bis(4′-cyclohexyl-4′-hydroxy-2′,3′-diazabuta-1′,3′-dien-1′-yl)-4-methylthiophenolato(3–)-S,N²,O(Cu^1,2)]-methanol-µ-(pyrazolyl-N,N′)-dicopper(II)

Abstract

Magnetostructural correlations are made on the matched pair of O‐bridged and S‐bridged binuclear Cu(II) complexes (Ia) and (Ib).

The structure, magnetism and EPR spectra of a (μ-thiophenolato)(μ-pyrazolato-N,N′) double bridged dicopper(ii) complex

“…60 As a result, the energy gap between symmetric and antisymmetric orbitals (ε(φ″ AS ) − ε(φ″ S )) is reduced, thus leading to a weaker antiferromagnetic interaction. As an example, due to the pyramidal disposition of the sulfur bridge atom, the antiferromagnetic interactions in thiophenolato/pyrazolato-bridged complexes is significantly weaker than the coupling observed for a related series of the approximately planar phenolato/pyrazolato-and alkoxido/pyrazolato-bridged complexes, [Cu 2 (L-O)( pz)], where L = 2,6-bis(4′cyclohexyl-4′-hydroxy-2′,3′-diazabuta-1′,3′-dien-1′-yl)-4-methylphenolate(3-) ( J 0 = −382 cm −1 ), 18 2,6-bis[(2-phenoxy)iminomethyl]-4-methylphenolate(3-) ( J 0 = −457 cm −1 ), 16 1,3-bis(salicylideneamino)propan-2-ol ( J 0 = −310 cm −1 ), 63 1,4-bis-(salicylideneamino)butan-2-ol ( J 0 = −545.6 cm −1 ), 68 and 1,5-bis-(salicylideneamino)pentan-3-ol ( J 0 = −595 cm −1 ). 63 The antiferromagnetic coupling J 0 = −26(2) cm −1 obtained here for [Cu 2 L( pz)(DMSO)] is stronger than J 0 = −3.6 cm −1 (using our definition of J 0 ) reported for [Cu 2 (L-S)( pz)(CH 3 OH)] 18 due to the smaller displacement of the bridging sulfur atom from the Cu-ligand best-plane and the greater Cu-S-Cu angle in the former compound.…”

“…1,2 Based on this, and in order to understand the factors responsible for the magnetic-exchange interactions occurring between metal centres coupled via bridging ligands, several types of binuclear metal complexes of compartmental ligands with various bridging groups such as pyrazolate, 14,15 phenolate, 16 alkoxide, 17 and thiophenolate 18 have been synthesized and studied both structurally and magnetically. 19 While the peculiar magnetic properties of bimetallic complexes of phenol-based compartmental ligands have been widely investigated, [20][21][22][23] very few papers have analyzed the magnetic properties of the corresponding thiophenolato-bridged complexes, 18,24,25 possibly because thiolates are more readily oxidized and the chemistry required to generate such compounds is less well-developed. Robson and coworkers 18,26 initially designed and synthesized two S-protected binucleating ligand precursors I and II (Scheme 1) from which some binuclear transition metal(II)-complexes were isolated (III in Scheme 1).…”

“…19 While the peculiar magnetic properties of bimetallic complexes of phenol-based compartmental ligands have been widely investigated, [20][21][22][23] very few papers have analyzed the magnetic properties of the corresponding thiophenolato-bridged complexes, 18,24,25 possibly because thiolates are more readily oxidized and the chemistry required to generate such compounds is less well-developed. Robson and coworkers 18,26 initially designed and synthesized two S-protected binucleating ligand precursors I and II (Scheme 1) from which some binuclear transition metal(II)-complexes were isolated (III in Scheme 1). [26][27][28][29] The free thiophenolato ligands are liberated via a metal-promoted S-deprotection process, occurring during the formation of the complex in a "one-pot" reaction.…”

“…atoms to the coordination spheres of the metals to the type III complexes. After the pioneering work of Robson et al 18,26 on these complexes, there was further no research on this class of compartmental thiophenolato-bridged complexes, and according to the Cambridge Structural Database (CSD), no structural data are yet available for type III complexes.…”

Magnetic properties of dinuclear copper(II) complexes with simple pyrazolate bridges

“…2 The pyrazolate bridge in binuclear copper() co-ordination compounds is generally present with another bridging group such as alcoholate, phenolate, thiolate, acetate or azide. [3][4][5][6][7][8][9][10][11] Another possibility is the use of pyrazole derived ligands, which present chelating arms at the 3 and 5 positions of the pyrazole moiety, thus permitting the incorporation of two metal centres in close proximity. [12][13][14][15][16] We herein report the syntheses, crystal structure and magnetic properties of binuclear copper() complexes, bibridged or monobridged by simple pyrazolate ligands.…”