The preformed nickel(II) complex of the 14-membered macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane (cyclam, L), when treated with 4,4 0 -(dimethylsilanediyl)diphthalic acid (H 4 A) in a DMF/H 2 O mixture (4:1 v/v) under heating, leads to [Ni(L)] 3 (HA) 2 Á3DMF (IÁDMF). Redissolution of this compound in a DMF/H 2 O/MeOH mixture (4:1:30 v/v/v) with mild acidification under gentle heating results in the formation of a similar compound but containing water and methanol molecules of crystallization, [Ni(L)] 3 (HA) 2 Á5H 2 OÁ2MeOH (IIÁH 2 O). At lower temperature and concentration of reactants and longer reaction time, single crystals of composition {[{Ni(L)} 3 (HA) 2 ]Á4CH 3 OH} n (IIÁMeOH) were isolated. Single-crystal X-ray diffraction analysis of this compound, which, according to PXRD is isostructural with (1,4,8,11-tetraazacyclotetradecane-4 N)trinickel(II)] methanol tetrasolvate], {[Ni 3 (C 18 H 13 O 8 Si) 2 (C 10 H 24 N 4 ) 3 ]Á4CH 3 OH} n . It is built up of the monoprotonated tricarboxylate HA 3À ligand coordinated in a monodentate manner in the axial positions of two crystallographically independent Ni II cations, one of which is located on a crystallographic inversion centre. Both metal ions adopt a slightly tetragonally elongated trans-N 4 O 2 octahedral geometry. The compound has a lamellar structure with polymeric layers oriented parallel to the (102) plane, which are in turn linked via hydrogen bonds involving protonated carboxylic acid groups of the ligand. Bulk compounds IÁDMF and IIÁH 2 O were characterized by FT-IR and diffuse reflectance spectroscopy and thermogravimetry, which provide evidence of their structural differences. research papers Acta Cryst. (2020). C76, 419-426 Gavrish et al. A 2D nickel(II) polymer 423 Figure 3(a) The crystal structure of IIÁMeOH, viewed down the [201] direction, and (b) a view of the layer parallel to the (102) plane. Methyl groups on the Si atom, H atoms on the C atoms of the macrocycle and the carboxylate groups, the minor-disorder component of the cyclam ligand and methanol molecules of crystallization have been omitted. Hydrogen bonds are shown as dashed lines. research papers Acta Cryst. (2020). C76, 419-426 Gavrish et al. A 2D nickel(II) polymer 425