QUANTITATIVE ZEOLITE TOPOLOGY CAN HELP TO RECOGNIZE ERRONEOUS STRUCTURES AND TO PLAN SYNTHESES

Eighty-five frameworks listed in the new Atlas and 11 dense tetrahedral structures are characterized with respect to smallest rings; bond angles, being part of such rings; symmetry; loop configuration; and topological and framework density. The properties are quantified by numbers so that general tendencies as well as exotic samples can be recognized: In diagrams, the parameters of 4-connected frameworks are found in relatively narrow fields, while some of the interrupted frameworks, one with partly octahedral coordination and one that was later found to be erroneous, appear outside the fields. Lowest density is obtained for structures of high symmetry with many small rings at the T-atoms. Zeolites and dense structures are distinct by the metric density but not by the topology. A comparison is made between 24 natural structures known in 1967 and the presently known 85 structures. Natural and synthetic samples are similar in many respects. However, some particular parameters and the loop configuration resembling a cube-vertex are hardly observed in natural samples.