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The reaction of the decadentate ligand tpmen (H4tpmen = N,N,N'N'-tetrakis[(6-carboxypyridin-2-yl)methyl]ethylenediamine) with MnCl2·4H2O in aqueous solution gives a homodinuclear complex [Mn2(H2O)2(tpmen)]·16H2O, which has been characterized by elemental analysis, thermal gravimetric and single-crystal X-ray diffraction analysis. The complex crystallizes in the orthorhombic system, space group Cmca, a = 28.786(5) Å, b = 11.5033(19) Å, c = 14.437(2) Å, Z = 8, R1 = 0.0432, wR2 = 0.0786. The tpmen ligand contains four picolinate groups, two of which bind each Mn(II) to form a dinuclear complex. The geometry around the Mn(II) is distorted octahedral with two nitrogen and two oxygen atoms from the picolinate groups and two oxygen atoms from coordinated water. The variable-temperature (2-300 K) magnetic susceptibilities shows an antiferromagnetic interaction between Mn(II) ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two new carboxylate-bridged clusters of [Ni 3 ] and [Cu 2 ] were obtained solvothermally. • The structures respectively bear a linear trinuclear or paddle-wheel dinuclear structure. • Their magneto-structural correlations were discussed detailedly. Two carboxylate-bridged transition metal clusters, trinuclear [Ni 3 (CPA) 6 (bipy) 2 ] (1) and dinuclear [Cu 2 (CPA) 4 (DMSO) 2 ] (2), have been successfully prepared respectively based on mixed ligands of 4-chlorophenylacetic acid (HCPA) and 2,2′-bipyridine (bipy) or the single ligand of HCPA. Single crystal X-ray diffraction analyses reveal that complex 1 crystallizes in triclinic P -1 space group and has a structure of linear trinuclear [Ni 3 ] cluster, and 2 crystallizes in monoclinic P 2 1 / n space group and includes a paddle-wheel dinuclear [Cu 2 ] entity. The magnetic susceptibilities of 1 and 2 were quantitatively analyzed based on a linear trinuclear [Ni 3 ] model with Hamiltonian Ĥ = - JŜ 1 Ŝ 2 - JŜ 2 Ŝ 3 and a dimer [Cu 2 ] model with Ĥ = - JŜ 1 Ŝ 2 , respectively, resulting in g = 2.18(1), J = -0.79(1) cm−1 for 1 and g = 2.19(1), J = -321(1) cm−1 for 2. These confirms that the neighboring spin centers both display antiferromagnetic coupling in 1 and 2. [ABSTRACT FROM AUTHOR]