2D polymeric water–chloride/bromide sheets comprising a unique pentagon-like dichloride/dibromide-trihydrate cluster in the solid state have been observed as [Co(bpca)2]+ (bpca = bis(2-pyrimidylcarbonyl)amidate anion) counterions. Both compounds were obtained by the reaction of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT) with CoX2 (X = Cl, Br) in water. Solid-state multinuclear magnetic resonance spectroscopy and XRD provide insight into the structures.
![Graphical abstract: Interaction of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT) with CoX2 (X = Cl, Br) in water: trapping of new self-assembled water–chloride/bromide clusters in a [Co(bpca)2]+ host (bpca = bis(2-pyrimidylcarbonyl)amidate anion)](http://hg.y866.cn/compound/lib/scimg/usr/1/C5NJ01125F.jpg)