Versatility in the Coordination Modes of n ‐Chlorobenzoato Ligands: Synthesis, Structure and Magnetic Properties of Three Types of Polynuclear Mn II Compounds

Three different types of polynuclear manganese(II) compounds with chlorobenzoato bridges were obtained from the reaction of Mn( n ‐ClC 6 H 4 COO) 2 with 1,10‐phenanthroline (phen): three trinuclear compounds [Mn 3 (μ‐ n ‐ClC 6 H 4 COO) 6 (phen) 2 ] with n = 2, 3, 4 ( 1 – 3 ), one one‐dimensional system [Mn(μ‐3‐ClC 6 H 4 COO) 2 (phen)] n ( 4 ) and one neutral dinuclear compound [{Mn(4‐ClC 6 H 4 COO)(phen)} 2 (μ‐4‐ClC 6 H 4 COO) 2 (μ‐H 2 O)] ( 5 ). Compounds 1 , 3 , 4 and 5 were characterized by X‐ray diffraction and show four different coordination modes for the carboxylate ligand: as a bidentate bridge in a syn – syn mode or syn – anti mode, as a monodentate bridge and as a terminal monodentate ligand. The five compounds show weak antiferromagnetic coupling; the J values are –2.9, –2.8, –2.8, –1.8 and –3.6 cm –1 for compounds 1 – 5 , respectively. Each type of compound may be distinguished by their characteristic EPR spectrum at 4 K. Fairly good simulations of the spectra at 4 K for the trinuclear compounds 1 – 3 were obtained with ground state ZFS parameters, D 5/2 and E 5/2 , of 0.16 cm –1 and 0.05 cm –1 ( 1 ), 0.16 cm –1 and 0.043 cm –1 ( 2 ) and 0.16 cm –1 and 0.053 cm –1 ( 3 ), respectively. For the dinuclear complex 5 , the best simulation of the spectrum at 4 K was obtained with ZFS parameters of the ion, D Mn and E Mn , of 0.187 cm –1 and 0.061 cm –1 , respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)