Synthesis and structure of a complex having a quartet ground state with three entirely different spin carriers: Nitronyl nitroxide, o-semiquinone, and Cu-II

A "spin diverse" S = 3/2 ground-state complex, NN-SQCuTp(Cum,Me), has been prepared. The three S = 1/2 spin carriers are nitronyl nitroxide (NN), o-se miquinone (o-SQ), and cupric ion. The solid-state structure of the Zn-II de rivative, NN-SQZnTp(Cum,Me) (C56H69BN8O4Zn), was determined: monoclinic, P2 (1)/c, a = 12.5781(12) Angstrom, b = 17.7408(17) Angstrom, c = 24.440(2) An gstrom, alpha = 90.00 degrees, beta = 98.240(2)degrees, gamma = 90.00 degre es, Z = 4. The results of X-ray structural characterization of the Zn-II de rivative suggest substantial interaction between the two spin carriers NN a nd o-SQ. Indeed, strong intramolecular exchange coupling has been determine d by variable-temperature magnetic susceptibility studies. Intraligand ferr omagnetic exchange is considerably greater than kT, such that only the trip let state is populated at 300 K, and Cu-II-ligand exchange is ferromagnetic , with J = +75 cm(-1).