A study of the single-crystal-to-single-crystal transformation induced by temperature variation for the chain polymer Cu­(II) complex with nitronyl nitroxide showed that an increase in the hydrostatic pressure of up to ∼0.07 GPa completely changes the intracrystalline displacements of molecules relative to one another. This, in turn, significantly affects the interaction energy of the unpaired electrons of the paramagnetic centers and hence the form of the temperature dependence of the magnetic susceptibility χT. The cooling of crystals under normal conditions causes a rearrangement of the intrachain exchange clusters {>N–•O–Cu­(II)–O•–N<} accompanied by a shortening of the distances between the paramagnetic centers. This changes the character of exchange interactions and generates multistage spin transitions. An increase in the hydrostatic pressure leads to a drastic change in the O···O distances between the nitroxyl fragments of adjacent chains, an increase in the antiferromagnetic exchange between them, and complete suppression of spin transitions.

The reaction of cobalt(II) pivalate with a spin-labeled Schiff base (HL(1)) in organic solvents formed trinuclear complex [Co3(Piv)2L(1)2L(2)2]·Solv (Solv is Me2CO and/or C7H16 and CH3CN) containing both nitroxide L(1) and the product of its single-electron reduction, nitrone L(2). The formation of [Co3(Piv)2L(1)2L(2)2] was a consequence of an unusual phenomenon, which we called "redox-induced change in the ligand coordination mode". A reduction of L(1) to L(2) led to a change in the set of donor atoms and even in the size of the metallocycle. This phenomenon was also found for mononuclear [CrL(1)2L(2)] and [FeL(1)2L(2)]·Me2CO.