Molecular formula
C18H15N3O4S
121 compounds have this formula on CompoundList.
- Molar mass
- 369.39g/mol
- Monoisotopic mass
- 369.0783Da
- Atoms
- 41
- Elements
- 5
- Rings plus double bonds
- 13
The formula C18H15N3O4S describes a molecule made of 18 carbon atoms, 15 hydrogen atoms, 3 nitrogen atoms, 4 oxygen atoms and 1 sulfur atom. It is written in Hill notation: carbon first, then hydrogen, then the other elements in alphabetical order. The formula tells you which atoms are present, not how they are connected, which is why several different chemicals can share it.
Elemental composition
- C Carbon × 1858.53%12.011 × 18 = 216.198 g/mol
- H Hydrogen × 154.09%1.008 × 15 = 15.120 g/mol
- N Nitrogen × 311.38%14.007 × 3 = 42.021 g/mol
- O Oxygen × 417.32%15.999 × 4 = 63.996 g/mol
- S Sulfur × 18.68%32.06 × 1 = 32.060 g/mol
Look up another formula
Compounds with the formula C18H15N3O4S
Isomers we list, best known first. Open one to see its structure, properties, safety data and suppliers.
Showing 1 to 100 of 121 compounds
Disperse Yellow 42
CAS 5124-25-4C18H15N3O4S
![8-Ethoxy-3-[5-(furan-2-ylmethylamino)-1,3,4-thiadiazol-2-yl]chromen-2-one chemical structure, C18H15N3O4S, CAS 690215-56-6](/s/VMFUKLIOWOJGFF-UHFFFAOYSA-N.svg)
8-Ethoxy-3-[5-(furan-2-ylmethylamino)-1,3,4-thiadiazol-2-yl]chromen-2-one
CAS 690215-56-6C18H15N3O4S
N-(5-(4-Methoxybenzyl)-1,3-thiazol-2-yl)-2-nitrobenzamide
CAS 303092-92-4C18H15N3O4S
![5-[[1-(1,3-Benzodioxol-5-yl)-2,5-dimethylpyrrol-3-yl]methylidene]-2-sulfanylidene-1,3-diazinane-4,6-dione chemical structure, C18H15N3O4S, CAS 443298-32-6](/s/LBPJNDQXYKHHOI-UHFFFAOYSA-N.svg)
5-[[1-(1,3-Benzodioxol-5-yl)-2,5-dimethylpyrrol-3-yl]methylidene]-2-sulfanylidene-1,3-diazinane-4,6-dione
CAS 443298-32-6C18H15N3O4S
![3-{2-[4-Oxo-2-(phenylamino)-4,5-dihydro-1,3-thiazol-5-yl]acetamido}benzoic acid chemical structure, C18H15N3O4S, CAS 101466-26-6](/s/XUQMMNGYEROGAT-UHFFFAOYSA-N.svg)
3-{2-[4-Oxo-2-(phenylamino)-4,5-dihydro-1,3-thiazol-5-yl]acetamido}benzoic acid
CAS 101466-26-6C18H15N3O4S
2-((Z)-2-((Z)-Benzylidenehydrazono)-3-(4-hydroxyphenyl)-4-oxothiazolidin-5-yl)acetic acid
CAS 303120-78-7C18H15N3O4S
![3-(1,1-Dioxido-2H-benzo[e][1,2,4]thiadiazin-3-yl)-1-ethyl-4-hydroxyquinolin-2(1H)-one chemical structure, C18H15N3O4S, CAS 303776-77-4](/s/DZYPLUQOZHFGDL-UHFFFAOYSA-N.svg)
3-(1,1-Dioxido-2H-benzo[e][1,2,4]thiadiazin-3-yl)-1-ethyl-4-hydroxyquinolin-2(1H)-one
CAS 303776-77-4C18H15N3O4S
N-(5-(4-Methoxybenzyl)-1,3-thiazol-2-yl)-4-nitrobenzamide
CAS 303092-91-3C18H15N3O4S
![N-(1,3-Benzodioxol-5-ylmethyl)-2-[6-(furan-2-yl)pyridazin-3-yl]sulfanylacetamide chemical structure, C18H15N3O4S, CAS 872703-99-6](/s/CESJYCBWFKONSK-UHFFFAOYSA-N.svg)
N-(1,3-Benzodioxol-5-ylmethyl)-2-[6-(furan-2-yl)pyridazin-3-yl]sulfanylacetamide
CAS 872703-99-6C18H15N3O4S
![N-[3-Cyano-4-(3,4-dimethoxyphenyl)-2-thienyl]-5-methyl-3-isoxazolecarboxamide chemical structure, C18H15N3O4S, CAS 717857-47-1](/s/AHJWIRBGLQWHQS-UHFFFAOYSA-N.svg)
N-[3-Cyano-4-(3,4-dimethoxyphenyl)-2-thienyl]-5-methyl-3-isoxazolecarboxamide
CAS 717857-47-1C18H15N3O4S
![(2-Cyanophenyl)methyl 3-[(1,1-dioxo-1,2-benzothiazol-3-ylidene)amino]propanoate chemical structure, C18H15N3O4S, CAS 874971-39-8](/s/PSRPHPPKZOMDEP-UHFFFAOYSA-N.svg)
(2-Cyanophenyl)methyl 3-[(1,1-dioxo-1,2-benzothiazol-3-ylidene)amino]propanoate
CAS 874971-39-8C18H15N3O4S
![N-[5-(4-Methoxybenzyl)-1,3-thiazol-2-yl]-3-nitrobenzamide chemical structure, C18H15N3O4S, CAS 290839-72-4](/s/DXHADNDBFOJQBU-UHFFFAOYSA-N.svg)
N-[5-(4-Methoxybenzyl)-1,3-thiazol-2-yl]-3-nitrobenzamide
CAS 290839-72-4C18H15N3O4S
N-(3-Methoxyphenyl)-2-methyl-4-(4-nitrophenyl)-1,3-thiazole-5-carboxamide
CAS 303793-12-6C18H15N3O4S
N-(4-Anilinophenyl)-2-nitrobenzenesulfonamide
CAS 328025-04-3C18H15N3O4S
![2-(2-(1,3-Dioxoisoindolin-2-yl)acetamido)-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carboxamide chemical structure, C18H15N3O4S, CAS 301224-19-1](/s/RCYKUEIKWLSPTR-UHFFFAOYSA-N.svg)
2-(2-(1,3-Dioxoisoindolin-2-yl)acetamido)-5,6-dihydro-4H-cyclopenta[b]thiophene-3-carboxamide
CAS 301224-19-1C18H15N3O4S
![Morpholine, 4-[[4-(2,6-dicyanophenoxy)phenyl]sulfonyl]- chemical structure, C18H15N3O4S, CAS 671183-51-0](/s/HJRNPWDDKFBVJO-UHFFFAOYSA-N.svg)
Morpholine, 4-[[4-(2,6-dicyanophenoxy)phenyl]sulfonyl]-
CAS 671183-51-0C18H15N3O4S
![N-[5-(2-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide chemical structure, C18H15N3O4S, CAS 886909-95-1](/s/OJUVDWYGAYBTIO-UHFFFAOYSA-N.svg)
N-[5-(2-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide
CAS 886909-95-1C18H15N3O4S
![N-[5-(3-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide chemical structure, C18H15N3O4S, CAS 886914-19-8](/s/WTQITDFYMRHWFB-UHFFFAOYSA-N.svg)
N-[5-(3-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide
CAS 886914-19-8C18H15N3O4S
![N-[5-(4-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide chemical structure, C18H15N3O4S, CAS 886918-54-3](/s/RFPGZWODYJCFEX-UHFFFAOYSA-N.svg)
N-[5-(4-Methylsulfanylphenyl)-1,3,4-oxadiazol-2-yl]-2,3-dihydro-1,4-benzodioxine-6-carboxamide
CAS 886918-54-3C18H15N3O4S
SIRT5 inhibitor 4
CAS 708992-34-1C18H15N3O4S
N-(2-Methoxy-4-nitrophenyl)-2-(quinolin-8-ylsulfanyl)acetamide
CAS 438605-62-0C18H15N3O4S
N-(5-(7-Ethoxybenzofuran-2-yl)-1,3,4-oxadiazol-2-yl)-2-(thiophen-2-yl)acetamide
CAS 922098-81-5C18H15N3O4S
![N-[(1Z)-4-Oxo-3-(phenylhydrazido)-1,4-dihydronaphthalen-1-ylidene]methanesulfonamide chemical structure, C18H15N3O4S, CAS 873855-70-0](/s/PIFZVXOSTPVPFC-UHFFFAOYSA-N.svg)
N-[(1Z)-4-Oxo-3-(phenylhydrazido)-1,4-dihydronaphthalen-1-ylidene]methanesulfonamide
CAS 873855-70-0C18H15N3O4S
N-(6-Acetyl-1,3-benzodioxol-5-yl)-2-(1H-benzimidazol-2-ylsulfanyl)acetamide
CAS 522593-62-0C18H15N3O4S
- 1-(4-(Benzo[d][1,3]dioxol-5-yl)thiazol-2-yl)-3-(4-methoxyphenyl)urea397277-02-0C18H15N3O4S
- 2-[6-(1,3-Benzodioxol-5-yl)pyridazin-3-yl]sulfanyl-N-(furan-2-ylmethyl)acetamide895458-26-1C18H15N3O4S
- N-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-2-((4-oxo-3,4-dihydroquinazolin-2-yl)thio)acetamide675197-89-4C18H15N3O4S
- 4-{2-[4-Oxo-2-(phenylamino)-4,5-dihydro-1,3-thiazol-5-yl]acetamido}benzoic acid101413-77-8C18H15N3O4S
- (E)-Ethyl 2-((3-methylisoxazole-5-carbonyl)imino)-3-(prop-2-yn-1-yl)-2,3-dihydrobenzo[d]thiazole-6-carboxylate946206-11-7C18H15N3O4S
- Methyl 5-(((6-benzamidopyridazin-3-yl)thio)methyl)furan-2-carboxylate1021055-63-9C18H15N3O4S
- Benzyl 2-((6-(furan-2-carboxamido)pyridazin-3-yl)thio)acetate1021026-26-5C18H15N3O4S
- N-(6-((2-(3-Methoxyphenyl)-2-oxoethyl)thio)pyridazin-3-yl)furan-2-carboxamide1021136-40-2C18H15N3O4S
- 1-(4-Methoxyphenyl)-3-((3-nitrobenzyl)thio)pyrazin-2(1H)-one946330-31-0C18H15N3O4S
- N-(5-(Benzo[d][1,3]dioxol-5-yl)-1,3,4-oxadiazol-2-yl)-2-(4-(methylthio)phenyl)acetamide922119-12-8C18H15N3O4S
- 7-Ethoxy-N-(5-(thiophen-2-ylmethyl)-1,3,4-oxadiazol-2-yl)benzofuran-2-carboxamide1021113-07-4C18H15N3O4S
- N-(5-(2-(Methylthio)phenyl)-1,3,4-oxadiazol-2-yl)-2,3-dihydrobenzo[b][1,4]dioxine-2-carboxamide886910-66-3C18H15N3O4S
- 3-[({5-[(3-Methylphenoxy)methyl]-1,3,4-thiadiazol-2-yl}carbonyl)amino]benzoic acid1142202-75-2C18H15N3O4S
- 4-({[5-(3-Methoxybenzyl)-1,3,4-thiadiazol-2-yl]-carbonyl}amino)benzoic acid1142209-78-6C18H15N3O4S
- Methyl 4-{[5-(anilinocarbonyl)-1,3,4-thiadiazol-2-yl]methoxy}benzoate1142210-42-1C18H15N3O4S
- Methyl 1-(4-methoxyphenyl)-6-oxo-4-(2-pyridinylsulfanyl)-1,6-dihydro-3-pyridazinecarboxylate338396-07-9C18H15N3O4S
- N-(1,3-Benzodioxol-5-yl)-4-oxo-2-(phenylamino)-5,6-dihydro-4H-1,3-thiazine-6-carboxamide669740-31-2C18H15N3O4S
- Methyl2-({[(5-phenyl-1,3,4-oxadiazol-2-yl)thio]acetyl}amino)benzoate573669-58-6C18H15N3O4S
- N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-2-[6-oxo-3-(thiophen-2-yl)pyridazin-1(6H)-yl]acetamide922895-55-4C18H15N3O4S
- N-(4-Anilinophenyl)-4-nitrobenzenesulfonamide28829-80-3C18H15N3O4S
- (5Z)-2-(3,4-Dimethoxyphenyl)-5-[(5-methyl-2-furyl)methylene][1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-one573950-15-9C18H15N3O4S
- Methyl 5-(2-methoxyphenyl)-2-[(4-pyridylcarbonyl)amino]-1,3-thiazole-4-carboxylate1374525-15-1C18H15N3O4S
- (E)-4-Ethoxy-N-(4-(4-nitrophenyl)thiazol-2(3H)-ylidene)benzamide313403-69-9C18H15N3O4S
- N-(6-Acetamidobenzo[d]thiazol-2-yl)-2,3-dihydrobenzo[b][1,4]dioxine-2-carboxamide681167-33-9C18H15N3O4S
- N~2~-[2-(1,3-benzothiazol-2-ylamino)-2-oxoethyl]-2,3-dihydro-1,4-benzodioxine-2-carboxamide1010872-16-8C18H15N3O4S
- Methyl 5-(4-methoxyphenyl)-2-[(2-pyridylcarbonyl)amino]-1,3-thiazole-4-carboxylate1374551-19-5C18H15N3O4S
- N-[5-[(4-Methoxyphenyl)methyl]-1,3,4-thiadiazol-2-yl]-1,3-benzodioxole-5-carboxamide510736-20-6C18H15N3O4S
- (E)-5-((5-(2-Nitrophenyl)furan-2-yl)methylene)-2-(pyrrolidin-1-yl)thiazol-4(5H)-one714924-04-6C18H15N3O4S
- Methyl 4-(2-((6-(furan-2-yl)pyridazin-3-yl)thio)acetamido)benzoate872703-87-2C18H15N3O4S
- N-(2-(6-Oxo-3-(thiophen-2-yl)pyridazin-1(6H)-yl)ethyl)benzo[d][1,3]dioxole-5-carboxamide946340-91-6C18H15N3O4S
- N-(Furan-2-ylmethyl)-N-(5-methoxybenzo[d]thiazol-2-yl)-5-methylisoxazole-3-carboxamide946202-65-9C18H15N3O4S
- 1-(2,3-Dihydro-1,4-benzodioxin-6-yl)-4-[3-(thiophen-2-yl)-1,2,4-oxadiazol-5-yl]pyrrolidin-2-one941962-67-0C18H15N3O4S
- 2-{[3-(1,3-Benzodioxol-5-ylmethyl)-4-oxo-3,4-dihydroquinazolin-2-yl]sulfanyl}acetamide777874-93-8C18H15N3O4S
- (E)-N-(6-Ethoxybenzo[d]thiazol-2-yl)-3-(3-nitrophenyl)acrylamide380469-83-0C18H15N3O4S
- 2-Cyano-N-[(furan-2-yl)methyl]-2-[3-(4-methoxyphenyl)-4-oxo-1,3-thiazolidin-2-ylidene]acetamide123651-17-2C18H15N3O4S
- N-(6-Acetamido-1,3-benzothiazol-2-yl)-2,3-dihydro-1,4-benzodioxine-6-carboxamide477553-68-7C18H15N3O4S
- N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-2-[6-(furan-2-yl)pyridazin-3-yl]sulfanylacetamide872723-70-1C18H15N3O4S
- Methyl 4-({[6-oxo-3-(thiophen-2-yl)pyridazin-1(6H)-yl]acetyl}amino)benzoate922855-62-7C18H15N3O4S
- N-(1,3-Benzodioxol-5-ylmethyl)-2-(6-oxo-3-thiophen-2-ylpyridazin-1-yl)acetamide899946-31-7C18H15N3O4S
- 4-(Benzo[d][1,3]dioxol-5-yl)-6-(thiophen-2-ylmethyl)-3,4,6,7-tetrahydro-1H-pyrrolo[3,4-d]pyrimidine-2,5-dione1021025-09-1C18H15N3O4S
- 2-(3-(Benzo[d][1,3]dioxol-5-yl)-6-oxopyridazin-1(6H)-yl)-N-(thiophen-2-ylmethyl)acetamide1211783-16-2C18H15N3O4S
- (2,3-Dihydrobenzo[b][1,4]dioxin-2-yl)(3-(3-(thiophen-2-yl)-1,2,4-oxadiazol-5-yl)azetidin-1-yl)methanone1323792-06-8C18H15N3O4S
- N-(5-(4-Oxo-4H-chromene-2-carbonyl)-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)acetamide1351653-59-2C18H15N3O4S
- 3-(1,1-Dioxido-3-oxo-1,2-benzothiazol-2(3H)-yl)-N-(1H-indol-4-yl)propanamide1374550-39-6C18H15N3O4S
- 3-(1,1-Dioxido-3-oxo-1,2-benzothiazol-2(3H)-yl)-N-(1H-indol-6-yl)propanamide1374551-40-2C18H15N3O4S
- 2-(1-(3-(Furan-2-yl)-1,2,4-oxadiazol-5-yl)-3-(methylthio)propyl)isoindoline-1,3-dione1809499-92-0C18H15N3O4S
- (Z)-N-(3-Allyl-4-methoxybenzo[d]thiazol-2(3H)-ylidene)-4-nitrobenzamide868375-97-7C18H15N3O4S
- (Z)-N-(3-Allyl-4-methoxybenzo[d]thiazol-2(3H)-ylidene)-3-nitrobenzamide868375-98-8C18H15N3O4S
- (Z)-N-(3-Allyl-4-methoxybenzo[d]thiazol-2(3H)-ylidene)-2-nitrobenzamide868376-63-0C18H15N3O4S
- 2-Cyano-N-[(furan-2-yl)methyl]-2-[3-(2-methoxyphenyl)-4-oxo-1,3-thiazolidin-2-ylidene]acetamide749219-21-4C18H15N3O4S
- 5-Nitro-N-[4-(5,6,7,8-tetrahydronaphthalen-2-yl)-1,3-thiazol-2-yl]furan-2-carboxamide684232-90-4C18H15N3O4S
- N-[5-(2,3-Dihydro-1,4-benzodioxin-6-yl)-1,3,4-oxadiazol-2-yl]-2-methylsulfanylbenzamide896353-15-4C18H15N3O4S
- N-(5-(2-(Methylsulfonyl)phenyl)-1,3,4-oxadiazol-2-yl)cinnamamide886921-70-6C18H15N3O4S
- N-(5-(3-(Methylsulfonyl)phenyl)-1,3,4-oxadiazol-2-yl)cinnamamide886928-29-6C18H15N3O4S
- N-(5-(4-(Methylsulfonyl)phenyl)-1,3,4-oxadiazol-2-yl)cinnamamide886910-37-8C18H15N3O4S
- 2-(4-Nitrophenoxy)-N-(2-pyridinyl)-N-(2-thienylmethyl)acetamide898480-00-7C18H15N3O4S
- N-(Furan-2-ylmethyl)-N-(6-methoxybenzo[d]thiazol-2-yl)-5-methylisoxazole-3-carboxamide946357-34-2C18H15N3O4S
- N-(1,3-Benzodioxol-5-yl)-4-oxo-6,7,8,9-tetrahydro-4H-pyrimido[2,1-b][1,3]benzothiazole-3-carboxamide948001-69-2C18H15N3O4S
- N-(5-(4-(Methylthio)phenyl)-1,3,4-oxadiazol-2-yl)-2,3-dihydrobenzo[b][1,4]dioxine-2-carboxamide886919-29-5C18H15N3O4S
- 6-[2-(5,6-Dimethyl-4-oxothieno[2,3-d]pyrimidin-3(4H)-yl)acetyl]-2H-1,4-benzoxazin-3(4H)-one942800-01-3C18H15N3O4S
- (E)-N-(5-((2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)methyl)-1,3,4-oxadiazol-2-yl)-3-(thiophen-2-yl)acrylamide1006971-32-9C18H15N3O4S
- 1-(4-Methoxyphenyl)-3-((4-nitrobenzyl)thio)pyrazin-2(1H)-one946328-17-2C18H15N3O4S
- Methyl 2-((5-(3-(methylthio)phenyl)-1,3,4-oxadiazol-2-yl)carbamoyl)benzoate1170938-73-4C18H15N3O4S
- N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-4-(4-methoxyphenyl)-1,2,3-thiadiazole-5-carboxamide1190276-33-5C18H15N3O4S
- 4-[({[6-Oxo-3-(thiophen-2-yl)pyridazin-1(6H)-yl]acetyl}amino)methyl]benzoic acid1246060-12-7C18H15N3O4S
- 3-(1,1-Dioxido-3-oxo-1,2-benzothiazol-2(3H)-yl)-N-(1H-indol-5-yl)propanamide1374516-83-2C18H15N3O4S
- 3-(1-(3-(Pyridin-2-yloxy)benzoyl)azetidin-3-yl)thiazolidine-2,4-dione2034236-34-3C18H15N3O4S
- Methyl 3-(6-(benzyloxy)pyrimidine-4-carboxamido)thiophene-2-carboxylate2034581-23-0C18H15N3O4S
- 7-Methoxy-N-(2-(4-oxothieno[3,2-d]pyrimidin-3(4H)-yl)ethyl)benzofuran-2-carboxamide1904021-70-0C18H15N3O4S
- (E)-3-(Benzo[d][1,3]dioxol-5-yl)-N-(2-(4-oxothieno[3,2-d]pyrimidin-3(4H)-yl)ethyl)acrylamide2035019-49-7C18H15N3O4S
- N-(2-(7-Oxofuro[2,3-c]pyridin-6(7H)-yl)ethyl)quinoline-8-sulfonamide2034324-30-4C18H15N3O4S
- N-([2,2'-Bifuran]-5-ylmethyl)-4-(1H-pyrazol-1-yl)benzenesulfonamide2034252-32-7C18H15N3O4S
- 2-Methanesulfonyl-N-(2-phenoxyphenyl)pyrimidine-4-carboxamide2094699-92-8C18H15N3O4S
- N-({[2,3'-Bifuran]-5-yl}methyl)-4-(1H-pyrazol-1-yl)benzene-1-sulfonamide2034442-68-5C18H15N3O4S
- N-(1,3-Benzodioxol-5-yl)-2-[[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl]acetamide497927-00-1C18H15N3O4S
- [2-(Benzylidenehydrazono)-3-(4-hydroxyphenyl)-4-oxo-1,3-thiazolidin-5-yl]acetic acidC18H15N3O4S
Frequently asked questions
What is the molar mass of C18H15N3O4S?
The molar mass of C18H15N3O4S is 369.39 g/mol, calculated from standard atomic weights for 18 carbon atoms, 15 hydrogen atoms, 3 nitrogen atoms, 4 oxygen atoms and 1 sulfur atom. The monoisotopic mass is 369.0783 Da.
How many compounds have the formula C18H15N3O4S?
CompoundList lists 121 compounds with the molecular formula C18H15N3O4S, including Disperse Yellow 42, 8-Ethoxy-3-[5-(furan-2-ylmethylamino)-1,3,4-thiadiazol-2-yl]chromen-2-one, N-(5-(4-Methoxybenzyl)-1,3-thiazol-2-yl)-2-nitrobenzamide. Compounds that share a formula are isomers. They contain the same atoms arranged differently, so their properties, uses and prices can be very different.
What is the degree of unsaturation of C18H15N3O4S?
C18H15N3O4S has a degree of unsaturation of 13. That is the total number of rings and pi bonds (a double bond counts as one, a triple bond as two) in any structure with this formula.