Cobalt(II) and nickel(II) complexes of isoquinoline‐1‐carboxylate

trans‐Di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­cobalt(II) dihydrate, Co(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, and trans‐di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­nickel(II) dihydrate, Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, contain the same isoquinoline ligand, with both metal atoms residing on a centre of symmetry and having the same distorted octahedral coordination. In the former complex, the Co—O(water) bond length in the axial direction is 2.167 (2) Å, which is longer than the Co—O(carboxylate) and Co—N bond lengths in the equatorial plane 2.055 (2) and 2.096 (2) Å, respectively]. In the latter complex, the corresponding bond lengths for Ni—O(water), Ni—O(carboxylate) and Ni—N are 2.127 (2), 2.036 (2) and 2.039 (3) Å, respectively. Both crystals are stabilized by similar stacking interactions of the ligand, and also by hydrogen bonds between the hydrate and coordinated water molecules.