Structure and Magnetism of an Ideal One-Dimensional Chain Antiferromagnet [CNH][Fe(SO)] with a Large Spin of = 5/2.

Isolated large-spin Heisenberg antiferromagnetic uniform chain is quite rare. Here, we have successfully synthesized an ideal one-dimensional (1D) = 5/2 linear-chain antiferromagnet [CNH][Fe(SO)], which crystallizes in a trigonal lattice with the space group 3. A broad maximum at = 18 K is observed in the magnetic susceptibility curve. Notably, no long-range magnetic ordering is observed down to 2 K even if the material has a large Curie-Weiss temperature of θ = -25.5 K. High-field magnetization at 2 K shows a linear increase until saturation at 30 T, and a high-field electron spin resonance (ESR) reveals the absence of a zero-field spin gap. The intrachain interaction and interchain interaction ' are determined. Quite a small ratio of '/ < 2.5 × 10 suggests that [CNH][Fe(SO)] behaves as an ideal 1D uniform linear-chain antiferromagnet, in which the magnetic ordering is prevented by the extremely small interchain interaction and quantum fluctuation even for a classical spin of = 5/2.