On the superexchange mechanism in polymeric, pyrazine-bridged copper(II) complexes

2,3-Pyrazinedicarboxylates of cobalt(II), nickel(II), and copper(II); magnetic properties and crystal structures

“…This is because the magnitude of the exchange is determined from the overlap of the dX2-yl magnetic orbital and the pyrazine T-system, which becomes significant only when the pyrazine ring is canted out of the xy-plane. In Cu(pyz)(NO,),, for example (27,28), where the canting angle is about 50°, the exchange interaction (-J = 3.7 cm-I) is significantly greater than that observed here for 6.…”

Magnetic order and enhanced exchange in the quasi-one-dimensional molecule-based antiferromagnet Cu(NO3)2(pyz)3

“…In 1 and 2 the angles between pyz and the plane containing the d x 2 Ày 2 orbitals are similar (511 and 551 respectively) and we find that J in 1 is smaller despite the tilt angle being closer to the theoetically ideal value of 451 which would be expected to maximize p-overlap. 18 This is consistent with an X-ray charge-density study on 1 and the 3D coordination polymer [Cu(NO 3 )(pyz) 2 ]NO 3 ÁH 2 O (3). 9 Bond ellipticity profiles ruled out p-type exchange between the Cu d yz and d xy orbitals and the pyz p orbitals, favouring a s-only exchange mechanism.…”

Synthesis, crystal structure and properties of bis(hexafluoroacetylacetonato)tetrazinecopper(II)

“…If we consider the complicated structure of 1 with different coordination polyhedrons and geometry, it is not unexpected to obtain a higher g value. Similar examples have been reported previously [26]. Furthermore, the dissociation and loss of some tetz at room temperature during sample preparation would also contribute a higher observed Curie constant when the magnetic data were processed using the molecule weight of the pure material.…”