Four new Cu(II)-azido complexes of formula [CuL(N(3))] (1), [CuL(N(3))](2) (2), [Cu(7)L(2)(N(3))(12)](n) (3), and [Cu(2)L(dmen)(N(3))(3)](n) (4) (dmen = N,N-dimethylethylenediamine) have been synthesized using the same tridentate Schiff base ligand HL (2-[1-(2-dimethylaminoethylimino)ethyl]phenol, the condensation product of dmen and 2-hydroxyacetophenone). The four compounds have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Complex 1 is mononuclear, whereas 2 is a single mu-1,1 azido-bridged dinuclear compound. The polymeric compound 3 possesses a 2D structure in which the Cu(II) ions are linked by phenoxo oxygen atoms and two different azide bridges (mu-1,1 and mu-1,1,3). The structure of complex 4 is a double helix in which two mu-1,3-azido-bridged alternating one-dimensional helical chains of CuL(N(3)) and Cu(dmen)(N(3))(2) are joined together by weak mu-1,1 azido bridges and H-bonds. The complexes interconvert in solution and can be obtained in pure form by carefully controlling the conditions. The magnetic properties of compounds 1 and 2 show the presence of very weak antiferromagnetic exchange interactions mediated by a ligand pi overlap (J = -1.77) and by an asymmetric 1,1-N(3) bridge (J = -1.97 cm(-1)), respectively. Compound 3 presents, from the magnetic point of view, a decorated chain structure with both ferro- and antiferromagnetic interactions. Compound 4 is an alternating helicoidal chain with two weak antiferromagnetic exchange interactions (J = -1.35 and -2.64 cm(-1)).

A tetra-nuclear, star-shaped hetero-metallic copper(II)-manganese(II) complex, [{CuL(H(2)O)}(2)(CuL)Mn](ClO(4))(2) (1) has been synthesized by reacting the "complex as ligand" [CuL] with Mn(ClO(4))(2) where H(2)L is the tetradentate di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Upon treatment with the polyatomic anions azide, cyanate, or thiocyanate in methanol medium, complex 1 transforms into the corresponding trinuclear species [(CuL)(2)Mn(N(3))(2)] (2), [(CuL)(2)Mn(NCO)(2)] (3) and [(CuL)(2)Mn(NCS)(2)] (4). All four complexes have been structurally and magnetically characterized. In complex 1 the central Mn(II) ion is encapsulated by three terminal [CuL] units through the formation of double phenoxido bridges between Mn(II) and each Cu(II). In complexes 2-4 one of the CuL units is replaced by a couple of terminal azide, N-bonded cyanate or N-bonded thiocyanate ions respectively and the central Mn(II) ion is connected to two terminal Cu(II) ions through a double asymmetric phenoxido bridge. Variable temperature magnetic susceptibility measurements show the presence of moderate ferrimagnetic exchange interactions in all the cases mediated through the double phenoxido bridges with J values (H = -JS(i)S(i + 1)) of -41.2, -39.8 and -12.6 cm(-1) (or -40.5 and -12.7 cm(-1) if we use a model with two different exchange coupling constants) for the tetranuclear MnCu(3) cluster in compound 1 and -20.0, -17.3 and -32.5 cm(-1) for the symmetric trinuclear MnCu(2) compounds 2-4. These ferrimagnetic interactions lead to spin ground states of 1 (5/2 - 3*1/2) for compound 1 and 3/2 (5/2 - 2*1/2) for compounds 2-4.

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Two new Mn(III) complexes of formulas [MnL(1)(N(3))(OMe)](2) (1) and [MnL(2)(N(3))(2)](n) (2) have been synthesized by using two tridentate NNO-donor Schiff base ligands HL(1){(2-[(3-methylaminoethylimino)-methyl]-phenol)} and HL(2) {(2-[1-(2-dimethylaminoethylimino)methyl]phenol)}, respectively. Substitution of the H atom on the secondary amine group of the N-methyldiamine fragment of the Schiff base by a methyl group leads to a drastic structural change from a methoxido-bridged dimer (1) to a single μ(1,3)-azido-bridged 1D helical polymer (2). Both complexes were characterized by single-crystal X-ray structural analyses and variable-temperature magnetic susceptibility measurements. The magnetic properties of compound 1 show the presence of weak ferromagnetic exchange interactions mediated by double methoxido bridges (J = 0.95 cm(-1)). Compound 2 shows the existence of a weak antiferromangetic coupling along the chain (J = -8.5 cm(-1)) through the single μ(1,3)-N(3) bridge with a spin canting that leads to a long-range antiferromagnetic order at T(c) ≈ 9.3 K and a canting leading to a weak ferromagnetic long-range order at T(c) ≈ 8.5 K. It also exibits metamagnetic behavior at low temperatures with a critical field of ca.1.2 T due to the weak antiferromagnetic interchain interactions that appear in the canted ordered phase.

Four new cadmium(II) complexes [Cd2(bz)4(H2O)4(μ2-hmt)]·Hbz·H2O (1), [Cd3(bz)6(H2O)6(μ2-hmt)2]·6H2O (2), [Cd(pa)2(H2O)(μ2-hmt)] n (3), and {[Cd3(ac)6(H2O)3(μ3-hmt)2]·6H2O} n (4) with hexamine (hmt) and monocarboxylate ions, benzoate (bz), phenylacetate (pa), or acetate (ac) have been synthesized and characterized structurally. Structure determinations reveal that 1 is dinuclear, 2 is trinuclear, 3 is a one-dimensional (1D) infinite chain, and 4 is a two-dimensional (2D) polymer with fused hexagonal rings consisting of CdII and hmt. All the CdII atoms in the four complexes (except one CdII in 2) possess seven-coordinate pentagonal bipyramidal geometry with the various chelating bidentate carboxylate groups in equatorial sites. One of the CdII ions in 2, a complex that contains two monodentate carboxylates is in a distorted octahedral environment. The bridging mode of hmt is μ2- in complexes 1−3 but is μ3- in complex 4. In all complexes, there are significant numbers of H-bonds, C−H/π, and π−π interactions which play crucial roles in forming the supramolecular networks. The importance of the noncovalent interactions in terms of energies and geometries has been analyzed using high level ab initio calculations. The effect of the cadmium coordinated to hmt on the energetic features of the C−H/π interaction is analyzed. Finally, the interplay between C−H/π and π−π interactions observed in the crystal structure of 3 is also studied.