Competing Large and Small Angles in a Double End‐On Azido Copper(II) Binuclear Complex: A Combined Experimental and Theoretical Study of Magnetic Interactions

Abstract

The structure and magnetic properties of double azidobridged Cu II binuclear complex 1 with the chelating chiral ligand (S,S)-2,2Ј-isopropylidenebis(4-phenyl-2-oxazoline) were analyzed by combining experimental and theoretical techniques. The Cu II ions adopt a square pyramidal geometry with different degrees of distortion, whereas the two endon azido bridges disposed at the equatorial positions exhibit significantly different Cu-N-Cu angles, 110.6 and 97.3°, which are respectively smaller and larger than the critical 108°value distinguishing the ferromagnetic and antiferromagnetic regimes. The asymmetry in 1 arises from the use of the bulky asymmetric ligand, giving rise to two different magnetic pathways between the Cu II ions. The magnetic pathway along the large Cu-N-Cu angle value dominates over the small one, resulting in a net antiferromagnetic behavior with J = -78.6 cm -1 . On the basis of wavefunction cal-

Metal ions directing the geometry and nuclearity of azido-metal(ii) complexes derived from bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)amine

“…[1][2][3][4] In addition to the terminal monodentate nature of the azido ligand [1][2][3][4] many bridging coordination modes were reported where a magnetic super-exchange mechanism is known to occur through various modes. [5][6][7][8][9][10][11][12][13][14][15][16] These include single and double μ 1,3 -N 3 (end-to-end, EE) [5][6][7][8][9][10][11][12][13][14][15][16][17] and μ 1,1 -N 3 (endon, EO), [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] μ 1,1,3 -N 3 , μ 1,1,1 -N 3 ...…”

Tricomponent Azide, Tetrazolate, and Carboxylate Cobridging Magnetic Systems: Ferromagnetic Coupling, Metamagnetism, and Single‐Chain Magnetism

“…The crossover from FM to AF is in good agreement with that predicted for double-azide-bridged Cu II dimers using DFT calculations. [23] Obviously, the FM interaction observed in the tetrazolate-bridging compound 1, which has f= 1168, does not follow this trend. We note that the azide bridge at this angle induces AF coupling, as suggested by experimental and theoretical studies, [23] and that the tetrazolate N-N bridge induces weak AF coupling, as indicated by a recent Cu II dinuclear compound with a double tetrazolate bridge.…”

“…[23] Obviously, the FM interaction observed in the tetrazolate-bridging compound 1, which has f= 1168, does not follow this trend. We note that the azide bridge at this angle induces AF coupling, as suggested by experimental and theoretical studies, [23] and that the tetrazolate N-N bridge induces weak AF coupling, as indicated by a recent Cu II dinuclear compound with a double tetrazolate bridge. [24] Orbital counter-complementarity [12a,b, 25] of the two dissimilar bridges may be evoked to explain the overall FM coupling observed in 1.…”

An Imidazolate‐ and Azide‐Bridged Copper(II) Coordination Polymer Consisting of Alternating Di‐ and Mononuclear Units

“…Therefore, the exchange interactions through the interchain EE-azide bridge (J 3 ) should be low. Secondly, in the double EO-azide-bridged dinuclear core, the magnetic 3d [32,33] and are known to be correlated to the Cu-N azide -Cu angle (θ). As θ increases from about 85 to 104°, J gradually decreases, and finally enters the antiferromagnetic regime (J Ͻ 0) when θ Ն104°.…”