A New Alternating Ferro‐Antiferromagnetic One‐Dimensional Azido‐Bridged (Arylazoimidazole)manganese(II), [Mn(TaiEt)(N₃)₂]_n [TaiEt = 1‐Ethyl‐2‐(p‐tolylazo)imidazole], Exhibiting Bulk Weak Ferromagnetic Long‐Range Ordering

Abstract

−), a versatile intermediary, coordinate to manganese(II) forming an alternating chain with the formula [Mn(TaiEt)(N 3 ) 2 ] n (1). The compound crystallizes in the triclinic P1 space group with a = 7.9297(7) Å , b = 9.5883(9) Å , c = 11.8366(11) Å , α = 103.555(2)°, β = 105.811(2)°, γ = 104.280(2)°, and Z = 2. The structure consists of neutral chains in which each manganese(II) center is alternately bridged by two end-on and two end-to-end azide ligands. The unsymmetrical arylazo heterocycle chelator creates a strong distortion around the metal center [N−Mn−NЈ bite 67.7°; Mn−NЈ(azo) distance 2.562 Å ]. The magnetic properties of 1 have been investigated over the temperature range 2−300 K. Magnetic data are analyzed

Thioether Bonded Nickel(II)‐Azoimidazole Complexes: Structures, Spectra and Electrochemical Oxidation to the Nickel(III) State

“…This observation does not fit to our previous experience with 3d-group metal complexes of azoimidazoles. In Mn II -azoimidazole-azido bridge the chelate, Mn[N(azo), N(imidazole)] chelate that Mn-N(azo) (2.54 Å) is longer than Mn-N(imidazole) (2.203 Å); [17,18] [12] Co[N(azo), N(imidazole)] unit Co-N(azo) (2.328 Å) Ͼ Co-N(imidazole) (2.010 Å); [19,20] Ni[N(azo), N(imidazole)] unit Ni-N(azo) (2.252 Å) Ͼ Ni-N(imidazole) (2.052 Å); [12,21] Cu[N(azo), N(imidazole)] unit Cu-N(azo) (2.632 Å) Ͼ Cu-N(imidazole) (1.973 Å). [9,22,23] The coordination of -S-R may have influence on the strength of bonding interaction.…”

Copper‐Azide‐Thioarylazoimidazoles – Structure, Spectra, Redox Properties, Magnetism and Theoretical Interpretation

“…Some of the transitions are new ( Table 2, Figure 3) in the complexes: these are characteristic of copper(II) azoheterocycles [16,19,22] and are the MLCT transitions involving dπ(Cu)Ǟπ*(arylazoheterocycle). By comparing them with values for copper(II)-1-alkyl-2-(arylazo)-imidazoles, [11][12][13]16] copper(II)-2(arylazo)pyridine, [19] copper(II)-pyridylthioazophenolates [22] and other pyridylthioethers, [23] we can assign the transitions at approximately 410 nm to the MLCT [dπ(Cu)Ǟπ*(azoimidazole)] band, and the absorption at approximately 740 nm is undoubtedly a d-d transition. [24] The visible ranges of the spectra of copper(I) complexes (3,4) show similar metal-to-ligand chargetransfer (MLCT) transitions at 710-765 nm and 410- complexes when bonded with conjugated organic chromophores.…”

“…These correspond to bridging ν asym -(N 3 ). [15,16,21] In complexes 3, ν(N 3 ) appears as a single sharp stretch at 2035-2045 cm -1 . The ν(N=N) and ν(C=N) appear at 1410-1415 and 1580-1590 cm -1 , respectively.…”

“…[24] The visible ranges of the spectra of copper(I) complexes (3,4) show similar metal-to-ligand chargetransfer (MLCT) transitions at 710-765 nm and 410- complexes when bonded with conjugated organic chromophores. [14][15][16] …”

“…[14][15][16] Azide may serve as an end-on (µ 1,1 ) and an endto-end (µ 1,3 ) bridging agent. In general the end-on coordination mode is associated with ferromagnetic coupling, whereas end-to-end bridging leads to antiferromagnetic interactions.…”