The Ground Spin States of Tris[p-(N-oxyl-N-tert-butylamino)phenyl] amine, -Methyl, and -Borane. Prospects of Further Studies

An exploratory study has been carried out on new poly(aminoxyl) radicals as potential bridging ligands for 2p/3d-hybrid-spin metal complexes having network structures. Temperature dependence of the magnetic susceptibility data on the title amine N in the range 2–300 K was analyzed to show that its ground state was a doublet with a quartet state lying 559 K (=1.11 kcal mol-1) above the doublet. B3LYP/6-31G*//B3LYP/6-31G computations on a simplified model molecule (Nʹ) confirmed the doublet ground state by 0.84 kcal mol-1. The methyl compound (C) is a triplet diradical with a singlet state lying 410 K above the triplet. The hexamethyl derivative (Bʹ) of the title borane B has a doublet ground state with an energy gap to a quartet state by 9.9 K. The electronic structures are described qualitatively by p-(N-oxyl-tert-butylamino)phenyl homologues of (·H2C) 3X in which X=N,C·, and B atoms, and carries two, one, and no PI-electrons, respectively. N and Bʹ showed two reversible redox waves. MnII(hfac)2 and C gave a black–violet crystalline complex in which the 3d and 2p spins ordered at 60 K.