A multifrequency high-field EPR (9-285 GHz) investigation of a series of dichloride mononuclear penta-coordinated Mn(II) complexes

The electronic structure of a series of I I penta-coordinated dichloride mononuclear Mn(I 1) complexes [Mn(L)Cl-2] (L = Cl-terpy, Br-terpy, OH-terpy, phenyl-terpy, tolyl-terpy, mesityl-terpy, EtO-terpy, Me2N-terpy, tBu(3)-terpy, py-phen, and dpya) has been investigated by a multifrequency EPR study (9-285 GHz). The X-ray structures of [Mn(Br-terpy)Cl-2], [Mn(EtO-terpy)Cl-2] [Mn(Me,N-terpy)Cl-2] and [Mn(tolyl-terpy)Cl-2] are described. The spin Hamiltonian parameters have been determined for all complexes and show that the steric and electronic effects of the N-tridentate ligand L do not induce appreciable variations on the zero field splitting parameters. The magnitude of D, close to 0.3 cm(-1), is governed by the chloride anion. High-field EPR spectroscopy allows the determination of electronic parameters of mononuclear Mn(II) complexes characterized by relatively large magnitudes of D and the unambiguous interpretation of the X-band spectra of these kinds of complexes. (c) 2005 Elsevier B.V. All rights reserved.