Two new tetranuclear complexes, [Zn(2)Cr(2)(NCS)(4)(Dea)(2)(HDea)(2)].4DMSO (1; DMSO = dimethyl sulfoxide) and [Zn(2)Cr(2)(NCS)(4)(Dea)(2)(HDea)(2)].2CH(3)CN (2), were prepared from zinc oxide, Reinecke's salt, NH(4)[Cr(NCS)(4)(NH(3))(2)].H(2)O, ammonium thiocyanate, and a nonaqueous solution of diethanolamine (H(2)Dea) in a reaction carried out under open air. Both compounds have similar centrosymmetric crystal structures based on a tetranuclear {Zn(2)Cr(2)(mu(3)-O)(2)(mu-O)(4)} core. Variable-temperature magnetic susceptibility measurements of 1 and 2 show weak antiferromagnetic coupling between chromium centers. The magnetic data and high-field, high-frequency electron paramagnetic resonance spectra were analyzed in terms of the spin Hamiltonian H = JS(1).S(2) - j(S(1).S(2) + mu(B)B{g(1)}S(1) + D(Cr){S(z1)(2) - S(1)(S(1) + 1)/3} + E(Cr)(S(x1)(2) - S(y1)(2)) + mu(B)B{g(2)}S(2) + D(Cr){S(z2)(2) - S(2)(S(2) + 1)/3} + E(Cr)(S(x2)(2) - S(y2)(2)) + D(12){S(z1)S(z2) - S(1).S(2)/3} + E(12)(S(x1)S(x2) - S(y1)S(y2)) with J = 13.7 cm(-1), j = 1.1 cm(-1), D(Cr) = 0.3864 cm(-1), E(Cr) = -0.1104 cm(-1), D(12) = -0.1873 cm(-1), and E(12) = -0.0155 cm(-1) for 1 and J = 9.4 cm(-1), j = 0.8 cm(-1), D(Cr) = 0.3564 cm(-1), E(Cr) = -0.0647 cm(-1), D(12) = -0.1850 cm(-1), and E(12) = -0.0112 cm(-1) for 2. Density functional theory (DFT) calculations were employed to calculate the zero-field splitting on Cr(3+) ions. Calculations of the exchange integrals J were attempted by using the "broken-symmetry" DFT method.

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A new heterometallic Mn/Cr molecular wheel complex has been synthesized using zerovalent manganese, Reineckes salt, ammonium thiocyanate and triethanolamine (H(3)tea) as starting materials. The compound [Mn(3)Cr(4)(NCS)(6)(Htea)(6)] (1) has been characterized in terms of its electrochemical, IR and EPR spectroscopic as well as its magnetic properties. The magnetic susceptibility and magnetization data were treated simultaneously during the optimization routine and resulted in J(Mn-Cr) = +0.43 cm(-1), J(Cr-Cr) = -4.75 cm(-1), J(Mn-Mn) = +1.78 cm(-1), g(eff) = 1.878 with the ground state S = 15/2.

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Single crystals of the title heterometallic compound, [Fe(C12H8N2)3][Cr(NCS)4(C12H8N2)]2·3CH3CN·H2O or [Fe(Cphen)3][Cr(NCS)4(phen)]2·3CH3CN·H2O, were pre­pared using the one-pot open-air reaction of iron powder, Reineckes salt and 1,10-phenanthroline (phen) in acetonitrile. The asymetric unit consists of an [Fe(phen)3]2+ cation, two [Cr(phen)(NCS)4]− anions, three acetonitrile solvent mol­ecules and a water mol­ecule. The Fe and Cr atoms both show a slightly distorted octa­hedral FeN6 and CrN6 coordination geometry with adjacent angles in the range 79.67 (12)–95.21 (12)°. No classical hydrogen bonding involving the water molecule is observed.