Intermolecular ferromagnetic interaction in the crystal of a diphenyl nitroxide derivative. The role of spin-polarized hydrogen atoms located near a neighboring N–O site

Ground Triplet Spirobiradical: 2,2′,7,7′-Tetra(tert-butyl)-9,9′(10H,10′H)-spirobiacridine-10,10′-dioxyl

“…Two dihydroacridine skeletons are connected by an sp 3 -hybridized carbon atom to form a cruciform-shaped structure, as indicated by a dihedral angle of 89.44(1)° between the two acridine planes. The N1–O1 and N2–O2 bond lengths are 1.293(2) and 1.291(2) Å, respectively, which are close to the corresponding values of 2 [1.290(1) and 1.283(2) Å, respectively] and typical of 9,10-dihydroacridin-10-oxyls. , The N1–C1–C6–C5, N1–C13–C8–C9, N2–C22–C27–C26, and N2–C33–C28–C29 torsion angles are 178.4(1)°, −175.0(1)°, −179.1(1)°, and 179.8(1)°, respectively. These findings suggest that both acridine rings possess a slight butterfly-like curvature (Figures S4 and S5).…”

Crystallography and Magnetism of Two 1-(4-Nitroxylphenyl)pyrroles

“…DANO has been the most studied diarylnitroxide magnetic system its derivatives BTAO, DMAO, DEAO, DBAO and DPAO, and bis[3- tert -butyl-5-( N - tert -butylaminoxyl)phenyl]nitroxide (bNPhNO) …”

Galvinoxyl-inspired dinitronyl nitroxide: structural, magnetic, and theoretical studies

“…1b. However, since both nitrones and nitroxides have an N–O length of about 1.3 Å, 16,19,37,48–85 the bond length between the N and neighbouring sp 2 carbon atoms is important to determine the electron state of the N–O site. In fact, there is a difference in the N–C sp 2 length; the average lengths for nitrones are 1.31 Å (N–O: 1.29 Å), 48–53 those for aryl tert -butyl nitroxides are 1.43 Å (N–O: 1.29 Å), 16,19,37,45,54–71 and those for 10-oxy-9(10 H )acridines are 1.41 Å (N–O: 1.29 Å).…”