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Silver(I) chloride reacts with 2‐mercapto‐3,4,5,6‐tetrahydropyrimidine (StpmH2, C4H8N2S) in DMSO with excess triethylamine to give a complex of formula {[Ag4Cl4(μ3‐StpmH2)4]n} (1). The product was characterized by elemental analyses, FTIR far‐IR, UV/Vis, and 1H and 109Ag NMR spectroscopic techniques. The 109Ag NMR spectroscopic data of the complexes {[Ag6(μ2‐Br)6(μ2‐StpmH2)4(μ3‐StpmH2)2]n} (2) and {[Ag4(μ2‐StpmH2)6](NO3)4}n (3) are also reported here for comparison. Crystal structure of complex 1 was determined by X‐ray diffraction at 100(1) K. Complex 1, C4H8AgClN2S, crystallized in the tetragonal system, space group P4cc, a = 15.7761(9) Å, b = 15.7761(9) Å, c = 6.9624(8) Å, V = 1732.8(2) Å3, Z = 2. Each metal ion is bonded to one terminal Cl atom and three μ3‐S atoms from three StpmH2 ligands. Four silver ions are bridged by four sulfur atoms forming an octagonal Ag4S4 core. Each AgI ion of one core is also bridged to an AgI ion of another core through a sulfur atom, which forms an infinite nanotube structure. A computational study utilizing the method of nucleus‐independent chemical shifts (NICS) showed that the Ag4S4 core exhibits strong quasiaromaticity at the geometric cage center. To the best of our knowledge, this is the first example of an AgI cluster that presents quasiaromaticity and stacking interactions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The use of the anion of 3-methyl-1,3,5-pentanetriol (mpt(3-)) in manganese carboxylate chemistry has afforded the new Mn(II/III)12 cluster [Mn(II)6Mn(III)6(mpt)6(CH3CO2)12(py)6]·3CH3CN (1·3CH3CN). Complex 1 was isolated in moderate yield by the reaction of Mn(CH3CO2)2·4H2O and H3mpt in a 2.6:1 molar ratio in a solvent mixture of acetonitrile and pyridine. The structure of 1 consists of alternating [Mn(II)2(CH3CO2)3(py)](+) and [Mn(III)2(μ-OR)2(CH3CO2)(py)](3+) dimeric units (three of each dimer), linked at each end by two alkoxo and one acetate bridges; the mpt(3-) ligands adopt the η(2):η(2):η(2):μ4 coordination mode. The overall metal topology of this new Mn12 wheel resembles a guitar plectrum, or a Reuleaux triangle. Complex 1 displays an unprecedented structural topology, being the first example of a Mn(II)6Mn(III)6 wheel constructed from alternating homovalent dimers and the only known Mn12 loop with the trigonal symmetry of a Reuleaux triangle (all other reported loops were ellipsoids). Variable-temperature, solid-state direct- and alternating-current magnetization studies were carried out on complex 1, revealing the presence of antiferromagnetic exchange interactions between the metal ions in the molecule, which lead to a spin ground-state value S = 0; the exchange coupling parameters J were calculated using density functional theory employing a hybrid B3LYP functional.

The synthesis, structural characterization and magnetic properties of a 1D coordination polymer based on a linear mixed valent [Mn(III)2Mn(II)] repeating unit are described. It displays single-chain magnet (SCM) behaviour with an energy barrier of ∼38 K and represents the first example of a mixed valent Mn-carboxylate SCM with a linear architecture.