Three Novel End-to-End Single Azido-Bridged Ferromagnetic Copper(II) Chains: Synthesis, Crystal Structure, and Magnetic Behavior

Abstract

Three new single end‐to‐end azido‐bridged copper(II) chains [Cu(L1)(N3)]n(ClO4)n (1), [Cu(L2)(N3)]n(ClO4)n (2), and [Cu(L3)(N3)]n(ClO4)n (3) using three different tridentate Schiff bases L1, L2, and L3, obtained from condensation of pyridine‐2‐carbaldehyde with N,N‐dimethylethane‐1,2‐diamine, N,N‐diethylethane‐1,2‐diamine, and 4‐(2‐aminoethyl)morpholine, respectively, have been synthesized, and their crystal structures have been determined by X‐ray diffraction methods. Complex 1, C10H15CuN6ClO4, crystallizes in an orthorhombic system, space group P212121, with a = 7.434(3), b = 12.047(4), c = 17.404(6) Å, and Z = 4; complex 2, C12H19CuN6ClO4, crystallizes in an orthorhombic system, space group Pna21, with a = 14.723(5), b = 13.829(5), c = 8.002(5) Å, and Z = 4 and complex 3, C12H17CuN6ClO5, crystallizes in an orthorhombic system, space group Pna21, with a = 13.837(15), b = 14.804(2), c = 8.050(4) Å, and Z = 4. Each structure consists of a single end‐to‐end azido‐bridged copper(II) 1D chain where each copper(II) center possesses a square pyramidal geometry. Magnetic susceptibility data, measured from 4 to 300 K, show weak ferromagnetic interaction through the end‐to‐end bridging azido pathway in all the complexes. The magnetic data were fitted to a high temperature series‐expansion for a one‐dimensional system with S = 1/2 local spin based on the Hamiltonian H = −JΣSi·Si+1 for all the complexes, giving the parameters J = +2.15 cm−1, g = 2.23 for 1, J = +3.61 cm−1, g = 2.16 for 2, and J = +2.06 cm−1, g = 2.17 for 3. This unusual magnetic behavior through the end‐to‐end bridging azido pathway has been correlated to the structural parameters. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Sonochemical Synthesis and Characterization of the New Micro-Hexagonal-Rod Lead (II)-Azido Coordination Compound

“…This ligand has attracted much attention for two main reasons. First, the azide anion can behave as a bidentate bridging ligand (end-to-on, l 1,1 -N 3 ''EO'' [9][10][11], or end-to-end, l 1,3 -N 3 , ''EE'', bridging modes [12][13][14][15]), and as a tridentate bridging ligand (l 1,1,1 -N 3 [11] or l 1,1,3 -N 3 [16][17][18][19]) (Scheme 1). Both types of bidentate coordinations can mediate ferromagnetic and antiferromagnetic interactions between the metallic ions.…”

Synthesis, crystal structure, and properties of copper(II) and manganese(II) complexes with azide and 3,4-di(2′-pyridyl)-1,2,5-oxadiazole

“…The pseudohalide azide has been widely utilized not only as a versatile bridging ligand but also as an excellent magnetic coupler [2][3][4][5]. The magnetic coupling mediated through azide bridges is generally ferromagnetic in nature for the end-on (µ-1,1 or EO) mode and antiferromagnetic for the end-to-end (µ-1,3 or EE) mode [6]. For dicopper(II) complexes with the square pyramidal coordination geometry, the nature of the interaction is also strongly dependent upon the disposition of the azide bridges between metal ions.…”

“…For dicopper(II) complexes with the square pyramidal coordination geometry, the nature of the interaction is also strongly dependent upon the disposition of the azide bridges between metal ions. For symmetric EO azido bridges, which assume a basal-basal disposition between Cu(II) ions, it has been experimentally and theoretically demonstrated that the exchange is ferromagnetic for lower Cu-N-Cu angles (<108 • ) and antiferromagnetic for higher angles, but the asymmetric EO azido bridges, which assume a basal-apical disposition, have been found to transmit interactions varying from weak ferromagnetic to medium antiferromagnetic [6][7][8][9][10].…”

One novel polynuclear complex [Cu2(bpc)2(N3)4Ca(H2O)2Na2(H2O)2]n having three different transition and non-transition metal centres

“…In the bridging mode pattern it can act in end-on or endto-end modes, the former mode is rather less known. The azido ligand is an efficient superexchange pathway for propagating magnetic interaction between the paramagnetic centres such as copper(II), giving dimeric, tetranuclear, cubane, 1D, 2D and 3D complexes [6,7].On the other hand, a bpc dianion (2,2 0 -bipyridyl-3,3 0 -dicarboxylate) functions as a bridging ligand in a tridentate fashion through its two pyridine nitrogen atoms and one carboxylate oxygen atom [8].So far most of the coordination polymers are built with homoleptic ligands. Several examples have been reported, including the ligand combinations of terephthalate and 4,4 0 -bipy [9], carboxylate and bipyridine [10,11], pyrazine and 4,4 0 -bipy [12], oxalate and pyrazine [13], oxalate and 4,4 0 -bipy [14,15], phthalate and 4,4 0 -bipy [16], etc.…”

“…In the bridging mode pattern it can act in end-on or endto-end modes, the former mode is rather less known. The azido ligand is an efficient superexchange pathway for propagating magnetic interaction between the paramagnetic centres such as copper(II), giving dimeric, tetranuclear, cubane, 1D, 2D and 3D complexes [6,7].…”