Investigation of possible spin frustration in isolated isosceles Mn^IIINi^II<inf>2</inf> Triangle: Experimental and theoretical studies

Spin frustration is a unique phenomenon in magnetic complexes, where if a spin fails to lower the total energy of the system, by orienting itself in relative to its adjacent spins, it is termed as frustrated. In this work, we discuss about the magnetic properties, and the possibility of spin frustration in our isolated [NiII2MnIII(hep)4(PhCO2)(N3)2] (Hhep = 2-(2-hydroxyethyl) pyridine) having an isosceles NiII2MnIII triangle. The triangular MnIIINiII2 core was held together by two μ3-alkoxide bridges. The magnetic properties of this complex were studied in detail. Variable temperature magnetic susceptibility data of the complex in the range of 1.8 to 300 K, indicates the presence of stronger intramolecular antiferromagnetic coupling between two NiII centres than between NiII and MnIII ions. Experimentally, the ground state of the complex was found to be a mixture of E(2,0) and E(1,1) states, suggesting our complex to be close to a spin frustrated system which was supported by ab initio calculations.