See what you will probably never see in reality, thanks to the PCOD

Two-dimensional B₂O₃ models (not DFT-optimized) as predicted by GRINSP

They can be porous too...

Construction of these B₂O₃ models (3D, 2D, 1D and 0D) described in 2005 and 2010 in refs. [1 and 8] - BO₃ triangles interconnected exclusively by corner-sharing. See other works in a 2012 paper and in a 2016 thesis. Data from the 2009 (766 models) and 2010 (5118 models) PCOD updates.

Not exhaustive list (more will be added during the next weeks, maybe)...

References for these GRINSP predictions :

1- Inorganic structure prediction with GRINSP. A. Le Bail, J. Appl. Cryst. 38 (2005) 389-395. http://journals.iucr.org/j/issues/2005/02/00/cg5019/
2- Predicted corner-sharing titanium silicates. A. Le Bail, Z. Kristallogr., Suppl. 26 (2007) 203-208. https://www.researchgate.net/publication/228093494_Predicted_corner-sharing_titanium_silicates
3- Powerpoint file : Contribution to the "Gordon Conference Style" Workshop : Global Optimisation Techniques Applied to the Prediction of Structures, 5-7 July 2006, University College London (.ppt or zipped)
4- Advances in structure prediction of inorganic compounds. A. Le Bail, Report of 2nd Algerian Crystallography Congress, Algérie (2005). http://arxiv.org/abs/cond-mat/0606025
5- Hypothetical AlF₃ crystal structures, A. Le Bail, F. Calvayrac, J. Solid State Chem., 179 (2006) 3159-3166.
6- Inorganic structure prediction: too much and not enough, A. Le Bail, Solid State Phenomena 130 (2007) 1-6.
7- Frontiers between crystal structure prediction and determination by powder diffractometry, A. Le Bail, Powder Diffraction, S23 (2008) S5-S12.
8- Databases of virtual inorganic crystal structures and their applications, A. Le Bail, Phys. Chem. Chem. Phys. 12 (2010) 8521-8530. DOI: 10.1039/c003907c
Etc - search by yourself after all...