Synthesis and X-ray structure of the MnIICl2 and MnIIIF2 complexes of N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane.: High-field electron paramagnetic resonance and density funtional theory studies of the Mn(III) complex.: Evidence for a low-lying spin triplet state

Two manganese complexes, (py(2)(NMe)(2))(MnCl2)-Cl-ll (1) and [(py(2)(NMe)2)(MnF2)-F-lll](+) (2), are here described with the macrocyclic ligand py(2)(NMe)(2) (py(2)(NMe)(2) = N,N-dimethyl-2,11-diaza[3,3](2,6)pyridinophane). For both, the crystal structure is reported. The UV-visible spectrum of 2 exhibits a very broad near-infrared (NIR) band corresponding to the transition between the two e(g)-type orbitals split by the Jahn-Teller effect. A negative D value of ca. -4 cm(-1) was estimated by high-field and high-frequency electron paramagnetic resonance (HF-EPR) spectroscopy, which was consistent with symmetry considerations. Density functional theory (DFT) calculations on 2 support the B-5(1) electronic ground state predicted from the X-ray structure. Moreover, to explain the large value of the D parameter, a spin triplet first excited spin state was postulated to occur at low energy. This was confirmed by the DFT calculations.