Two W^V–Mn^IIIbimetallic assemblies built by octacyanotungstate(v) and Mn^IIISchiff bases: molecular structures and a spin-flop transition

Abstract

Two W(V)-Mn(III) bimetallic compounds, [Mn(Cl-salmen)(H(2)O)2]{[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8].2H(2)O (1.2H(2)O) [5-Clsalmen = N,N'-(1-methylethylene)bis(5-chlorosalicylideneiminato) dianion], which contains trinuclear Mn(2)W and isolated Mn(III) moieties, and [Mn(3-MeOsalcy)(H(2)O)2]3[W(CN)(8)].2H(2)O (2.2H(2)O) [3-MeOsalcy = N,N'-(trans-1,2-cyclohexanediylethylene)bis(3-methoxysalicylideneiminato) dianion] molecules were prepared in redox processes and characterized using X-ray analysis and magnetic measurements. Compound 1 is composed of the {[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8]}- trimer, in which two CN groups among eight in [W(CN)8](3-) bridge W(5+) and two Mn(3+) ions and the remaining CN ligands are hydrogen-bonded to water molecules or unbound, and the [Mn(Cl-salmen)(H(2)O)2]+ cation. Subsequently, two water molecules of the isolated cation are subject to hydrogen bonds. For 2, there are no covalent bonds among the subunits and six serial stacks of [Mn(3-MeOsalcy)(H(2)O)2]+ units are all hydrogen-bonded. The many hydrogen bonds found in both complexes eventually lead to three-dimensional networks. The magnetic studies for 1 reveal that antiferromagnetic interactions (J = -5.4 cm(-1)) between W(V) and Mn(III) centers within the trimer are transmitted via the bridging CN groups. Intermolecular antiferromagnetic couplings (zJ' = -0.2 cm(-1)) are also observed. The static and dynamic magnetic data of 1 demonstrate the existence of a field-induced spin-flop transition occurring among the clusters and monomeric molecules.

Neutral Low-Dimensional Assemblies of a Mn(III) Schiff Base Complex and Octacyanotungstate(V): Synthesis, Characterization and Magnetic Properties

“…Some bond distances and angles defining the coordination polyhedrons geometry are shown in Table 2. The W-C bond distances vary from 2.151(7) to 2.168(6) Å with average value of 2.156(6) Å and W-C-N angles are close to 180 º with a greatest deviation from linearity of 1.58 º, which is consistent with the data obtained for related compounds [50,57,69,70,77]. The coordination environment of the Mn ion is an elongated tetragonal bipyramid because of the Jahn-Teller distortion.…”

“…The Mn-N-C bond angle is less than 180° and equal to 160.8°. Such a flexion is typical for the cyanide bridged Mn III -M(CN)n complexes [69][70][71]57,77,82,84,85]. As in the case of related 0D [82] and 1D [48] compounds, [Mn III (SB + )M III (CN)6(H2O)], M III = Fe, Mn, and Cr, the Schiff-base ligand is in an envelope conformation with a torsion angle comprising the Nimine-C-C-Nimine core and a dihedral angle between aromatic rings.…”

“…However, the assemblies of the paramagnetic [W(CN)8] 3− precursor and manganese(III) Schiff base complex, [Mn(SB)] + , are fairly limited and poorly studied in comparison with the large family of bimetallic compounds comprising of [Mn(SB)] + cation and the 3d metal hexacyanides that are extensively investigated both structurally and magnetically [76]. To the best of our knowledge, so far only six bimetallic low-dimensional magnetic systems involving [Mn(SB)] + and [W(CN)8] 3− units have been reported [55,54,[69][70][71]77].…”

Neutral Low-Dimensional Assemblies of a Mn(III) Schiff Base Complex and Octacyanotungstate(V): Synthesis, Characterization, and Magnetic Properties

“…Some bond distances and angles defining the coordination polyhedron geometry are shown in Table 2. The W-C bond distances vary from 2.151(7) to 2.168(6) Å with an average value of 2.156(6) Å and the W-C-N angles are close to 180 • with the greatest deviation from linearity of 1.58 • , which is consistent with the data obtained for the related compounds [50,57,69,70,77]. The coordination environment of the Mn ion is an elongated tetragonal bipyramid because of the Jahn-Teller distortion.…”

“…However, the assemblies of the paramagnetic [W(CN) 8 ] 3− precursor and manganese(III) Schiff base complex, [Mn(SB)] + , are fairly limited and poorly studied in comparison with the large family of bimetallic compounds comprised of the [Mn(SB)] + cation and the 3d metal hexacyanides that are extensively investigated both structurally and magnetically [76]. To the best of our knowledge, so far only six bimetallic low-dimensional magnetic systems involving [Mn(SB)] + and [W(CN) 8 ] 3− units have been reported [54,55,[69][70][71]77].…”