Magnetostructural Investigation of Orthogonal 1-Aryl-3-Phenyl-1,4-Dihydrobenzo[e][1,2,4]triazin-4-yl Derivatives

3-Phenyl-1,4-dihydrobenzo[e][1,2,4] triazinyl radicals with the N(1) position substituted with naphth-2-yl (1b), naphth-1-yl (1c), pyren-1-yl (1d), anthracen-9-yl (1e), 2-tri-fluoromethylphenyl (1f), 3-trifluoromethylphenyl (1g), and 2-iodophenyl (1h) were characterized by using single-crystal X-ray diffraction, variable-temperature magnetic susceptibility, and DFT computational methods. The substituent at N(1) is essentially orthogonal to the heterocycle plane in 1f and 1h, and with a high torsion angle in 1c and 1d. Radicals 1c and 1h form unusual infinite chains with crisscrossing hetero-co-facial pi-pi interactions, whereas radical 1d forms analogous homo-co-facial arrangements. Infinite chains of homo-co-facial pi-pi dimers are found in 1b, 1f and 1g; in the latter the position of the CF3 group controls the slippage of the dimers in the chain. No pi-pi parallel arrangements were found in 1e. Magnetic susceptibility measurements demonstrated strong antiferromagnetic interactions in 1b (J= -264 +/- 4 cm(-1)) and 1f (J= -134 +/- 1 cm(-1)), while weak intradimer ferromagnetic interactions were found in 1g (J(2)=+ 21 perpendicular to 1 and J(1)= -15 perpendicular to 1 cm(-1)). Other derivatives exhibit typical weak antiferromagnetic exchange interactions in a range of -5 to -10 cm(-1).