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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Triplet Spin-State Capped Deltahedral Structures Rather than Singlet Spin-State Oblatocloso Structures as
Artiom Găină-Gardiuta1, Alexandru Lupan1, R Bruce King2
1Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, RO-400028 Cluj-Napoca, Romania.
Abstract:
Density functional studies show that the singlet spin-state flattened oblatocloso deltahedral structures found experimentally in the dimetallaboranes Cp*2Re2BH2 (Cp* = Me5C5; n = 8-12) of the third row group 7 element rhenium are not favored for analogous dimetallaboranes Cp2Mn2B2H2 (n = 8-14) of its first row congener manganese. Instead, the energetically preferred structures for the dimanganaboranes are higher spin-state triplet and quintet spin-state structures. This appears to be related to the lower ligand field splittings in complexes of the first row transition-metal manganese relative to analogous complexes of the third row transition-metal rhenium. The lowest-energy Cp2Mn2B2H2 (n = 8-13) structures typically have a central MnB2 closo deltahedron with one face capped by the second CpMn unit. However, for the 14-vertex Cp2Mn2B12H12 system the lowest-energy structures consist of B12 icosahedra with faces capped by both CpMn units. The thermochemistry of cluster buildup reactions of the type Cp2Mn2B2H2 + BH → Cp2Mn2B1H1 suggests that the 11- and 13-vertex structures are likely to be favored products in reactions of cyclopentadienylmanganese derivatives with borane sources. The paramagnetism of the predicted triplet and quintet spin states for the lowest-energy dimanganaboranes Cp2Mn2B2H2 (n = 8-14) suggests possible applications in novel magnetic materials.
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