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Dimeric [Mn(salpn)NCS] 2 (1) and polymeric [Mn(salpn)NCS] n (2) are formed by the reaction of Mn(CH 3 CO 2 ) 2 . 4H 2 0, the schiff base, and thiocyanate. The formation of the two polymorphic forms is solvent and temperature dependent. 1: orthorhombic, space group Pbca, with a = 12.573(2) A, b = 13.970(7) A, c = 18.891(9) A, and Z = 8. 2: orthorhombic, space group Pna2 1 , with a = 12.5277(14) A, b = 11.576(2) A, c = 11.513(2) A, and Z= 4. The dimers in 1 are held together by weak noncovalent S...π (phenyl) interactions leading to a chain along the a-axis. Each monomeric unit of the polymer in 2 is related to its adjacent ones by a 2-fold screw axis leading to a helix along the c-axis. The exchange coupling is nondetectable in the dimer. The magnetic susceptibility of the helical chain fits a classical chain law with J = -3.2 cm - 1 and shows a weak ferromagnetic ordering below 7 K due to spin canting effects.

Two structurally significant polyiodides have been synthesized as salts of manganese(II) trischelates and characterized by three-dimensional X-ray crystallographic data. The complex, [Mn(phen)3](I3)2 (1), where phen = 1,10-phenanthroline, crystallizes in the hexagonal space group R 3 with 6 mononuclear cations in a cell of dimensions, a = b = 16.456(3) A; c = 25.864(4) A. The structure has been refined to the final R1 (wR2) values of 0.0365 (0.0782) based on 1981 (F ≥ 4σF) observed independent reflections. The structure of the [Mn(phen)3]2+ cation is unexceptional, whereas there are two types of symmetric I3− ions with I–I distances of 2.828(1) and 2.912(1) A. The longer I3− ions and the trischelate cations form layers of hexagonal network, while the shorter I3− ions are present as linkages between the layers in the crystal. The complex, [Mn(bpy)3](I3)1.5(I8)0.25 (2), where bpy = 2,2′-bipyridine, crystallizes in the monoclinic space group C2/c with 8 mononuclear cations in a cell of dimensions, a = 29.321(1) A; b = 12.9177(4) A; c = 23.2863(8) A; β = 120.950(2)°. The structure has been refined to the final R1 (wR2) values of 0.0536 (0.1310) based on 4192 (F ≥ 4σF) observed independent reflections. The structure consists of [Mn(bpy)3]2+ cations, two types of I3− ions, and infinite linear polyiodide chains of the composition, (I82−)n. Powder diffuse reflectance spectra measured for the complexes are similar exhibiting features at 23.0, 20.8, 18.5 and 17.2 kK, and are characteristic of the presence of I3− ions. Room temperature magnetic susceptibility measurements gave the magnetic moments of 5.85 and 6.05 μB for 1 and 2, respectively; the values are consistent with the expected spin-only magnetic moment for high-spin d5 manganese(II) complexes. Single crystal EPR spectral measurements with the applied field aligned parallel to the trigonal or pseudo-trigonal symmetry axis of the molecules gave zero-field splitting (D) values of 0.154 cm−1 (g = 2.06) and 0.066 cm−1 (g = 2.03) for 1 and 2, respectively. A comparison of the conductivities of the complexes in a single crystal form reveals a higher anisotropic conductivity for 2, which is attributed to the presence of linear polyiodide chains.