Solvothermal synthesis, structures, and magnetic properties of NiII compounds directed by N,N′-bridging auxiliary ligands

Syntheses, Crystal Structures, and Magnetic Properties of Two Mononuclear Nickel‐Nitronyl Nitroxide Radical Compounds

“…The best fit yields g Ni = 2.33, g rad = 2.00, D = 31.51 cm –1 and R = 6.11 × 10 –3 ( R = Σ[( χ M T ) obsd –( χ M T ) calcd ] 2 /Σ[( χ M T ) obsd ] 2 ). The g Ni value is consistent with the previously reported Ni II systems with a octahedral coordination arrangement 25,27…”

“…The direct‐current (dc) magnetic susceptibility of 1 was measured in the temperature range of 2–300 K in a dc field of 5000 Oe (Figure 4). The χ M T value of 1 at room temperature is 0.82 cm 3 · K · mol –1 , which is much smaller than the value expected for one Ni II ion (1.00 cm 3 · K · mol –1 for g = 2.0 and S = 1)25 and one radical (0.375 cm 3 · K · mol –1 ), which may indicate that the antiferromagnetic interaction between the Ni II ion and NIToPy radical is so strong that it is obvious even at room temperature. The χ M T values decrease rapidly with further decreasing the temperature, and reach a minimum of 0.51 cm 3 · K · mol –1 at 16 K, further confirming the strong antiferromagnetic interaction.…”

“…The χ M T value for 2 at room temperature is 2.00 cm 3 · K · mol –1 , which is near the sum value of one uncoupled Ni II ion (1.21 cm 3 · K · mol –1 ) ( g ≈ 2.22 and S = 1)25 and two free IM4Py radicals (0.75 cm 3 · K · mol –1 ) . In the temperature range of 40–300 K, the χ M T value is almost unchanged as the temperature decreasing (Figure 5).…”