Five alkali metal manganese(III) fluorophosphates, K2Mn(PO3F)F3 (I), Rb2Mn(PO3F)F3 (II), Rb2Mn2(PO3F)(PO4)F3 (III), Rb3Mn3(PO3F)2(PO4)F5 (IV), and CsMn(PO3F)F2 (V), were successfully synthesized using a hydrothermal method. The monofluorophosphate anion (PO3F)2− groups work as “chemical scissors” to promote low-dimensional spin structures with the aid of alkali metal cations. I and II had an S = 2 uniform chain structure formed by corner-sharing trans-MnO2F4 octahedra. III contained a quasi one-dimensional S = 2 spin chain composed of trans-MnO4F2 octahedra and trans-MnO2F4 octahedra through vertex-sharing fluorine atoms running along the [1−10] direction, whereas V exhibited a zigzag S = 2 spin chain built from the facial-MnO3F3 octahedron. In contrast, IV constitutes weakly coupled S = 2 spin trimers, where the three-dimensional (3D) framework contains two-dimensional {Mn3O4F4(PO3F)2}2− layers formed by trinuclear Mn-octahedral units via corner-sharing fluorine atoms separated by PO3F tetrahedra. Magnetic measurements confirmed that I and II possess antiferromagnetic (AFM) long-range ordering at low temperature, with intrachain exchange couplings Jintra/kB = −12.1(1) K for I and Jintra/kB = −8.1(2) K for II. The magnetic behaviour of IV was very complex, with three successive magnetic transitions owing to weak AFM coupling among S = 2 spin trimers. V shows an alternating S = 2 one-dimensional (1D) chain with canted AFM ordering at 16.5 K.
The isolation of a stable persistent carbazole-stabilized boron-centered monoradical anion 1˙−, which has a high spin density at the B atom, has been reported. It is characterized using the crystal structure and UV-vis absorption spectrum, as well as electron paramagnetic resonance spectroscopy. Interestingly, the B–N bond was activated by the boron-centered radical anion 1˙−, which had not been reported before.