A calcium(II) coordination polymer showing two different bridging 2-carbamoyl-4-nitrobenzoate coordination modes

Abstract

Aqueous reaction of CaCO3 with 2-carbamoyl-4-nitrobenzoic acid (2-ca-4nbaH) results in the formation of a 1-D coordination polymer [Ca(H2O)2(2-ca-4nba)2] (1), which crystallizes in the centrosymmetric triclinic space group P1 bar. The structure consists of a central Ca(II), two coordinated waters, a symmetrical bridging (mu 2 eta(1):eta(1)) 2-ca-4nba, and a tridentate bridging (mu 2 eta(2):eta(1)) 2-ca-4nba. The calcium in 1 is coordinated by two water molecules and five oxygens of four symmetry-related 2-ca-4nba, resulting in a distorted pentagonal bipyramidal {CaO7} polyhedron. Pairs of {Ca(H2O)2} units are linked into a 1-D coordination polymer extending along the a-axis with the aid of pairs of bridging 2-ca-4nba ligands. In the infinite chain, alternating pairs of Ca(II) ions exhibit Ca...Ca separations of 4.124 and 4.855 angstrom.