Crystal structure, assembly process, and single-molecule magnet behavior of a triangular prismatic {Co9} cluster.

Using the polydentate ligand of H4L with the CoII ion, a triangular prism-type nine-nucleus cluster [Co9(L)3(CH2OCH2OH)6]·3.5H2O ({Co9}-Eg, H4L = 6,6'-(1H,1'H-[3,3'-bi(1,2,4-triazole)]-5,5'-diyl)dipicolinic acid) was constructed. Ion fragmentation during the formation of the {Co9}-Eg cluster was tracked using time-dependent electrospray ionization mass spectrometry. In addition, we proposed two possible formation processes (i) H4L → CoL → Co2L → Co6L3 → Co7L3 → Co9L3 and (ii) H4L → CoL → Co2L → Co3L → Co5L2 → Co7L3 → Co9L3. Magnetic studies show that {Co9}-Eg exhibits slow relaxation under a static zero field at low temperature, which is the main characteristic of single molecule magnets (SMMs).

Solvent effects on the structures and magnetic properties of two doubly interpenetrated metal-organic frameworks.

Two doubly interpenetrated coordination polymers [Co2(BDC)2(bpt)2]·nSolvent based on dimeric secondary building units and crystallizing with distinct solvent molecules (-H2O and -MeOH for nSolvent = 2H2O and MeOH·H2O, respectively) were obtained by employing 1,4-benzenedicarboxylate (BDC) and 1H-3,5-bis(4-pyridyl)-1,2,4-triazole) (bpt) as linkers. The structures consist of a square grid of dimers bridged by BDC and pillared by bpt. Thermogravimetry and PXRD indicate that the frameworks are stable and are retained up to 400 °C, but the structures are modified irreversibly. -H2O, high-symmetry Pna21, exhibits antiferromagnetic coupling within the dimer, while -MeOH, low-symmetry P21/n, exhibits ferromagnetic coupling. Upon desolvation, the -de and -de couplings are antiferromagnetic but reduced. Subsequent resolvation to -H2O and -MeOH resulted in a slight increase of the antiferromagnetic coupling without attaining the virgin states. The interesting difference of magnetic properties between -H2O and -MeOH, the solvated/desolvated phases, particularly at low temperature, indicates that there is a prominent solvent effect.

Samarium(III)-catalyzed C(sp3)-H bond activation: synthesis of indolizines via C-C and C-N coupling between 2-alkylazaarenes and propargylic alcohols.

A new rare earth metal and samarium-catalyzed C(sp(3))-H bond activation is reported in which 2-alkylazaarenes and propargylic alcohols were converted to indolizines. This process operates under mild conditions and solvent-free conditions. A broad scope of coupling partners has been established, and a likely mechanism has also been suggested.

Diaqua-bis(2,2'-biimidazole)cobalt(II) 4,4'-dicarboxy-biphenyl-3,3'-di-car-boxylate.

In the title compound, [Co(C(6)H(6)N(4))(2)(H(2)O)(2)](C(16)H(8)O(8)), the Co(II) cation and the organic anion occupy different crystallographic inversion centres and, as a consequence, the asymmetric unit comprises two half-mol-ecules. The benzene groups are coplanar. The four coordinating N atoms of the two bidentate biimidazole ligands define the equatorial plane of a slightly distorted octa-hedral CoO(2)N(4) geometry, and the water O atoms lie in the axial coordination sites. Translational (a,) and inversion-related symmetry operations link the Co complex mol-ecules and the negatively charged carboxyl-ate anions via inter-molecular N-H⋯O and O-H⋯O hydrogen bonds into sheets parallel to (01). The coordinated water mol-ecules connect the sheets through O-H⋯O hydrogen bonds, forming a three-dimensional framework. In addition, two intra-molecular O-H⋯O hydrogen bonds are observed between the carboxyl and carboxyl-ate groups.