Preparation, Crystal Structures, and Thermal Studies of Alkaline Earth Nitrocarboxylates

Abstract

Abstract The preparation, crystal structures, and thermal properties of [Ca(pyr) 2 (4‐nba) 2 ] n ( 1 ) (pyr = pyrazole; 4‐nba = 4‐nitrobenzoate) {[Ca(H 2 O) 2 (3‐npth)] · H 2 O} n ( 2 ) (3‐npth = 3‐nitrophthalate), [Mg(H 2 O) 5 (3‐npth)] · 2H 2 O ( 3 ), and [Mg(H 2 O) 4 (2‐nba) 2 ] ( 4 ) (2‐nba = 2‐nitrobenzoate) are reported. The anhydrous Ca II compound 1 and the diaqua Ca II ‐3‐nitrophthalate monohydrate 2 are one‐dimensional coordination polymers containing a hexacoordinate Ca II ion located on a center of inversion in 1 and a heptacoordinated Ca II ion in 2 . In 1 , the 4‐nitrobenzoate moiety acts as a μ 2 ‐bridging bidentate ligand, whereas the 3‐nitrophthalate anion exhibits a μ 3 ‐bridging pentadentate coordination mode in 2 . The hexacoordinate Mg II ‐containing compounds 3 and 4 do not contain a [Mg(H 2 O) 6 ] 2+ unit and the central Mg II ion is coordinated to at least one monodentate carboxylate unit namely the monodentate 3‐npth molecule in 3 and two trans monodentate 2‐nba molecules in 4 . Hydrogen bonding between the lattice water molecules results in the formation of a water dimer in 3 . A comparative study of 17 alkaline earth nitrocarboxylates is described.