Complexes of boric acid with sodium- and magnesium-salicylates were prepared and analyzed to examine the structural consequences resulting from the coordination of the salicylate ligand in mono- and bis-chelate modes. The complexes were isolated from aqueous solutions and characterized by FTIR (Fourier Transform Infrared), TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) techniques. Interpretation of their spectral patterns and thermal stabilities established systematic differences and allowed a direct comparison between the mono- and bis-chelate structures. Magnesium bis-salicylatoborate, [Mg(H2O)6][B(Sal)2]·4H2O, was obtained in crystal form and presented as a new type of double-layered material, a unique feature among the salicylatoborate structures reported so far.