10-Vertex closo-carborane: a unique ligand platform for porous coordination polymers

1,10-Dicarboxy-1,10-dicarba-closo-decaborane, a classical dicarboxylate spacer ligand type similar to the prototypical terephthalic acid, proved to be different not only from the latter, but also from its closest relative compound, 1,12-dicarboxy-closo-1,12-dicarbadecaborane, with regard to the topology of its derived PCPs. Highly porous and robust compounds of zinc (rob net) and cobalt ('quasi' pcu) as well as a topologically unexpected copper compound (lvt) define the individuality of the 10-vertex carborane cage as a new fundamental spacer type in PCP chemistry. A combination of a lower steric demand compared to the 12-vertex analogue, a preferred orientation angle of 45 degrees between the carboxylate planes and a moderately low rotation barrier are held responsible for the uniqueness of the 10-vertex analogue.