High-Spin Nitrenes with s-Triazine Skeleton

Abstract

Heteroatomic high-spin molecules are suitable for a model study of room-temperature stable molecular based magnetics. We studied high-spin nitrenes (S = 1 and 2) with s-triazine skeleton, which were generated by the photolysis of the polyazide precursor. We identified mononitrene 1 (S = 1) and bisnitrene 2 (S = 2) for the first time by single-crystal ESR measurements. The fine-structure parameters were determined by the angular dependence of resonance fields. The determined fine-structure parameters were |D| = 1.402 cm⁻¹ and |D| = 0.280 cm⁻¹ for mononitrene 1 and bisnitrene 2, respectively. The large D values indicate that π-spin delocalization effects were hampered by introducing heteroatoms to π-spin systems. The hyperfine splittings due to the monovalent nitrogen nucleus of 1 were observed with magnetic field along the principal axis of the fine structure tensor. The hyperfine splitting constant was about 0.0018 cm⁻¹. The temperature dependence of ESR signals showed that 1 and 2 were triplet and quintet in the ground state, respectively.

Key Words:

• high-spin nitrene
• s-triazine
• single-crystal
• ESR
• heteroatomic perturbation
• hyperfine
• splittings