No abstract

The reaction of N,N-bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH), NaSCN/NaN(3), and metal (M) ions [M = Mn(II), Fe(II/III), Co(II)] in MeOH, leads to the isolation of a series of monomeric, trimeric, and tetrameric metal complexes, namely [Mn(bpaeOH)(NCS)(2)] (1), [Mn(bpaeO)(N(3))(2)] (2), [Fe(bpaeOH)(NCS)(2)] (3), [Fe(4)(bpaeO)(2)(CH(3)O)(2)(N(3))(8)] (4), [Co(bpaeOH)(NCS)(2)] (5), and [Co(3)(bpaeO)(2)(NO(3))(N(3))(4)](NO(3)) (6). These compounds have been investigated by single crystal X-ray diffractometry and magnetochemistry. In complex 1 the Mn(II) is bonded to one bpaeOH and two thiocyanate ions, while in complex 2 it is coordinated to a deprotonated bpaeO(-) and two azide ions. The oxidation states of manganese ions are 2+ for 1 and 3+ for 2, respectively, indicating that the different oxidation states depend on the type of binding anions. The structures of monomeric iron(II) and cobalt(II) complexes 3 and 5 with two thiocyanate ions are isomorphous to that of 1. Compounds 1, 2, 3, and 5 exhibit high-spin states in the temperature range 5 to 300 K. 4 contains two different iron(III) ions in an asymmetric unit, one is coordinated to a deprotonated bpaeO(-), an azide ion, and a methoxy group, and the other is bonded to three azide ions and two oxygens from bpaeO(-) and a methoxy group. Two independent iron(III) ions in 4 form a tetranuclear complex by symmetry. 4 displays both ferromagnetic and antiferromagnetic couplings (J = 9.8 and -14.3 cm(-1)) between the iron(III) ions. 6 is a mixed-valence trinuclear cobalt complex, which is formulated as Co(III)(S = 0)-Co(II)(S = 3/2)-Co(III)(S = 0). The effective magnetic moment at room temperature corresponds to the high-spin cobalt(II) ion (∼4.27 μ(B)). Interestingly, 6 showed efficient catalytic activities toward various olefins and alcohols with modest to excellent yields, and it has been proposed that a high-valent Co(V)-oxo species might be responsible for oxygen atom transfer in the olefin epoxidation and alcohol oxidation reactions.

Chiral copper(ii) complexes of the types [Cu(II)(R/S-ppme)(3)](ClO(4))(2) and [Cu(II)(R/S-ppme)(2)(SO(4))] have been synthesized by reactions of Cu(ClO(4))(2).6H(2)O and CuSO(4).5H(2)O with R/S-ppme in methanol under aerobic conditions (R/S-ppme = (R/S)-(+/-)-1-phenyl-N-(pyridine-2-ylmethylene)ethanamine). All complexes were isolated and characterized by X-ray crystallography and circular dichroism (CD): (Lambda)-[Cu(II)(R-ppme)(3)](ClO(4))(2) (1), (Delta)-[Cu(S-ppme)(3)](ClO(4))(2).H(2)O (2), (Delta)-[Cu(II)(R-ppme)(2)(SO(4))].4CH(3)OH (3), and (Lambda)-[Cu(II)(S-ppme)(2)(SO(4))].4CH(3)OH (4). 1 and 2 with ClO(4)(-) anions are formed as tris(R/S-ppme) copper(ii) complexes, while 3 and 4 with SO(4)(2-) are formed as bis(R/S-ppme) copper(ii) complexes. The structures of 1 with R-ppmes and 4 with S-ppmes show the same absolute configurations (Lambda). In contrast, 2 with S-ppmes and 3 with R-ppmes exhibit Delta configurations. In the electron paramagnetic resonance (EPR) spectra of 1 and 3, both compounds demonstrate z-axis elongated structures. The CD spectra of 1 and 2 show Cotton effects in an enantiomeric pattern; those of 3 and 4 also display the same effects.

In the title thio­cyanate-coordinated aza-macrocyclic copper(II) complex, [Cu(NCS)2(C24H38N6)], the CuII atom is coordinated by the four secondary N atoms of the aza-macrocyclic ligand and by the two N atoms of the thio­cyanate ions in a tetra­gonally distorted octa­hedral geometry. The average equatorial Cu—N bond length is shorter than the average axial Cu—N bond length [2.010 (2) and 2.528 (4) Å, respectively]. An N—H⋯N hydrogen-bonding inter­action between the secondary amine N atom and the adjacent thio­cyanate ion leads to a polymeric chain along the a axis.

A zigzag tetranuclear [Fe(4)(bpaeO)(2)(CH(3)O)(2)(N(3))(8)] possesses two different high-spin ferric sites and both ferromagnetic and antiferromagnetic interactions exist within the iron(III) ions.