Natural compounds where only a few hundred halogen containing compounds exist, the ring double bond equivalents contain no negative RDBEs. S (valence = 6) : 166 structural isomers.S (valence = 4) : 95 structural isomers.S (valence = 2) : 24 structural isomers.Correct use of LEWIS and SENIOR rules together with Molecular Isomer Generators is the RDBE or DBE values of molecular formulas are of For advanced structure elucidation processes the Now this will generate a wrong result using the RDBE formula. Sulfone (v=6) and phosphine (v=3) and phophonates (v=5). Now simply imagine a formula or compound which has different sulfur and phosphorus goups included (thioether or thiol v=2, One of the more simpler reasons why this formula is of no great help is, that complex organic mixtures contain multiple elements, which also can have different valence states. There are hundreds of such examples, especially from organic compounds containing halogenes (F,Cl,Br,I) together with sulfur, nitrogen and phosphorous.

Well if one should ignore all the double bonds why calculate in the first place? And the fourth example the existing bis(pentafluorosulfur)methane CH2F10S2 has a negative ring double bond equivalent of -4. The second one has 2 double bonds which should be ignored? The third formula C4H8O3S has 3 double bonds, but only a RDBE of 1. The first formula C3H8H3S2 has no rings and double bonds which OK. Novel formalism of was devolped for that purpose.

That is the reason modern formula generators also report an RDBE range and not a single value. Even worse, this formula in its original definition also produces wrong values. Relic from times when only a few people knew about graph theory in chemistry and had no access to fast computers and structure generators. Double Bond Equivalents (DBE) are calculated from valence values of elements contained in a formula and should tell the number of bonds - or rings.

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