Molecular formula
C16H18N4OS
155 compounds have this formula on CompoundList.
- Molar mass
- 314.41g/mol
- Monoisotopic mass
- 314.1201Da
- Atoms
- 40
- Elements
- 5
- Rings plus double bonds
- 10
The formula C16H18N4OS describes a molecule made of 16 carbon atoms, 18 hydrogen atoms, 4 nitrogen atoms, 1 oxygen atom 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 × 1661.12%12.011 × 16 = 192.176 g/mol
- H Hydrogen × 185.77%1.008 × 18 = 18.144 g/mol
- N Nitrogen × 417.82%14.007 × 4 = 56.028 g/mol
- O Oxygen × 15.09%15.999 × 1 = 15.999 g/mol
- S Sulfur × 110.20%32.06 × 1 = 32.060 g/mol
Look up another formula
Compounds with the formula C16H18N4OS
Isomers we list, best known first. Open one to see its structure, properties, safety data and suppliers.
Showing 1 to 100 of 155 compounds
![1-[[Oxo(3-pyridinyl)methyl]amino]-3-(4-propan-2-ylphenyl)thiourea chemical structure, C16H18N4OS, CAS 474244-19-4](/s/PLTDUXXHYQOSGF-UHFFFAOYSA-N.svg)
1-[[Oxo(3-pyridinyl)methyl]amino]-3-(4-propan-2-ylphenyl)thiourea
CAS 474244-19-4C16H18N4OS
![(1E)-4,4,6,8-Tetramethyl-4H-pyrrolo[3,2,1-ij]quinoline-1,2-dione 1-thiosemicarbazone chemical structure, C16H18N4OS, CAS 522659-87-6](/s/YLYYQECETGLXLP-UHFFFAOYSA-N.svg)
(1E)-4,4,6,8-Tetramethyl-4H-pyrrolo[3,2,1-ij]quinoline-1,2-dione 1-thiosemicarbazone
CAS 522659-87-6C16H18N4OS
![N-Cyclopentyl-2-[[6-(2-pyridinyl)-3-pyridazinyl]thio]acetamide chemical structure, C16H18N4OS, CAS 893994-76-8](/s/RSSDRQCVHNIBGP-UHFFFAOYSA-N.svg)
N-Cyclopentyl-2-[[6-(2-pyridinyl)-3-pyridazinyl]thio]acetamide
CAS 893994-76-8C16H18N4OS
1-Piperidin-1-yl-2-(6-pyridin-4-ylpyridazin-3-yl)sulfanylethanone
CAS 872987-33-2C16H18N4OS
![6,6-Dimethyl-9-(3-methylthiophen-2-yl)-5,6,7,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8(4H)-one chemical structure, C16H18N4OS, CAS 537003-58-0](/s/IGIZMOMXCYQAAX-UHFFFAOYSA-N.svg)
6,6-Dimethyl-9-(3-methylthiophen-2-yl)-5,6,7,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8(4H)-one
CAS 537003-58-0C16H18N4OS
![8-Amino-4-butyl-2,3-dihydro-1H-cyclopenta[4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-7(8H)-one chemical structure, C16H18N4OS, CAS 488801-73-6](/s/ZVFYNPLSSNVBJM-UHFFFAOYSA-N.svg)
8-Amino-4-butyl-2,3-dihydro-1H-cyclopenta[4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-7(8H)-one
CAS 488801-73-6C16H18N4OS
2-(4,6-Dimethyl-pyrimidin-2-ylsulfanyl)-acetic acid (1-PH-ethylidene)-hydrazide
CAS 60458-66-4C16H18N4OS
![(2E)-2-(4,4,6,9-Tetramethyl-2-oxo-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazinecarbothioamide chemical structure, C16H18N4OS, CAS 578000-77-8](/s/VFGNCQWEYISYNG-UHFFFAOYSA-N.svg)
(2E)-2-(4,4,6,9-Tetramethyl-2-oxo-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazinecarbothioamide
CAS 578000-77-8C16H18N4OS
![N'-{(E)-[4-(dimethylamino)phenyl]methylidene}-2-(pyridin-2-ylsulfanyl)acetohydrazide chemical structure, C16H18N4OS, CAS 326000-67-3](/s/ACYZPUAPCIDNPP-WOJGMQOQSA-N.svg)
N'-{(E)-[4-(dimethylamino)phenyl]methylidene}-2-(pyridin-2-ylsulfanyl)acetohydrazide
CAS 326000-67-3C16H18N4OS
1-Piperidin-1-yl-2-(6-pyridin-2-ylpyridazin-3-yl)sulfanylethanone
CAS 894000-61-4C16H18N4OS
3-(5-(Allylthio)-4-(2-methoxyethyl)-4H-1,2,4-triazol-3-yl)-1H-indole
CAS 852144-45-7C16H18N4OS
1-(Piperidin-1-yl)-2-((6-(pyridin-3-yl)pyridazin-3-yl)thio)ethanone
CAS 872987-32-1C16H18N4OS
![1-Amino-5-morpholin-4-yl-6,7,8,9-tetrahydrothieno[2,3-c]isoquinoline-2-carbonitrile chemical structure, C16H18N4OS, CAS 118663-21-1](/s/GZAXGZGXVBYGQK-UHFFFAOYSA-N.svg)
1-Amino-5-morpholin-4-yl-6,7,8,9-tetrahydrothieno[2,3-c]isoquinoline-2-carbonitrile
CAS 118663-21-1C16H18N4OS
1-(4-Phenylpiperazin-1-yl)-2-(pyrimidin-2-ylsulfanyl)ethanone
CAS 403833-62-5C16H18N4OS
![6-Amino-3-tert-butyl-4-(5-methyl-2-thienyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile chemical structure, C16H18N4OS, CAS 309289-81-4](/s/GRTCREZSSTVRAU-UHFFFAOYSA-N.svg)
6-Amino-3-tert-butyl-4-(5-methyl-2-thienyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile
CAS 309289-81-4C16H18N4OS
![6-Amino-3-tert-butyl-4-(3-methyl-2-thienyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile chemical structure, C16H18N4OS, CAS 316361-85-0](/s/BSMIPPJGDXQOCG-UHFFFAOYSA-N.svg)
6-Amino-3-tert-butyl-4-(3-methyl-2-thienyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile
CAS 316361-85-0C16H18N4OS
N-Cyclopentyl-2-(6-pyridin-4-ylpyridazin-3-yl)sulfanylacetamide
CAS 872701-47-8C16H18N4OS
4-(((4-Ethyl-5-methyl-4H-1,2,4-triazol-3-yl)thio)methyl)-5-methyl-2-phenyloxazole
CAS 1115892-93-7C16H18N4OS
![N-[7-(2-Furylmethyl)-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4-yl]-N,N-dimethylamine chemical structure, C16H18N4OS, CAS 126996-63-2](/s/CNAKLWURDUBDTD-UHFFFAOYSA-N.svg)
N-[7-(2-Furylmethyl)-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4-yl]-N,N-dimethylamine
CAS 126996-63-2C16H18N4OS
N-(4,6-Dimethyl-1,3-benzothiazol-2-yl)-1-ethyl-5-methyl-1H-pyrazole-3-carboxamide
CAS 1170224-51-7C16H18N4OS
![4-Isopropyl-1-(2-methoxyphenyl)-7-(methylthio)-1H-pyrazolo[3,4-d]pyridazine chemical structure, C16H18N4OS, CAS 1105204-83-8](/s/CUARECAYSJFPKL-UHFFFAOYSA-N.svg)
4-Isopropyl-1-(2-methoxyphenyl)-7-(methylthio)-1H-pyrazolo[3,4-d]pyridazine
CAS 1105204-83-8C16H18N4OS
![N-(6-Isopropyl-3-methylbenzo[d]thiazol-2(3H)-ylidene)-1-methyl-1H-pyrazole-3-carboxamide chemical structure, C16H18N4OS, CAS 1020490-02-1](/s/AHRHQNRVXGAFLD-UHFFFAOYSA-N.svg)
N-(6-Isopropyl-3-methylbenzo[d]thiazol-2(3H)-ylidene)-1-methyl-1H-pyrazole-3-carboxamide
CAS 1020490-02-1C16H18N4OS
![(E)-1-Ethyl-N-(3,4,6-trimethylbenzo[d]thiazol-2(3H)-ylidene)-1H-pyrazole-5-carboxamide chemical structure, C16H18N4OS, CAS 1173472-82-6](/s/CAEVGGIVCWFRQU-UHFFFAOYSA-N.svg)
(E)-1-Ethyl-N-(3,4,6-trimethylbenzo[d]thiazol-2(3H)-ylidene)-1H-pyrazole-5-carboxamide
CAS 1173472-82-6C16H18N4OS
![N-(4-Isopropylbenzo[d]thiazol-2-yl)-1,3-dimethyl-1H-pyrazole-5-carboxamide chemical structure, C16H18N4OS, CAS 1013784-26-3](/s/UJMYOEGQWCQJKW-UHFFFAOYSA-N.svg)
N-(4-Isopropylbenzo[d]thiazol-2-yl)-1,3-dimethyl-1H-pyrazole-5-carboxamide
CAS 1013784-26-3C16H18N4OS
- N-(3-Ethyl-5,7-dimethylbenzo[d]thiazol-2(3H)-ylidene)-1-methyl-1H-pyrazole-3-carboxamide1173315-44-0C16H18N4OS
- N-(1-Cyano-1-cyclopropylethyl)-2-[(1-methyl-1H-1,3-benzodiazol-2-yl)sulfanyl]acetamide1211168-18-1C16H18N4OS
- 2-Cyclohexyl-6-(3-methyl-1H-pyrazol-4-yl)-thieno[3,2-d]pyrimidin-4(3H)-one1330782-72-3C16H18N4OS
- 2-(Cyclopentylmethyl)-6-(3-methyl-1H-pyrazol-4-yl)-thieno[3,2-d]pyrimidin-4(3H)-one1330782-56-3C16H18N4OS
- 3-Methylsulfanylspiro[7H-[1,2,4]triazino[5,6-d][3,1]benzoxazepine-6,1'-cyclohexane]41384-02-5C16H18N4OS
- 3-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)propyl)-2-mercaptoquinazolin-4(3H)-one1001519-24-9C16H18N4OS
- 2-[(4-Methylbenzyl)thio]-5-propyl[1,2,4]triazolo[1,5-a]pyrimidin-7(4H)-one899377-07-2C16H18N4OS
- 2-(1,3-Benzothiazol-2-yl)-4-[(dimethylamino)methylene]-5-propyl-2,4-dihydro-3H-pyrazol-3-one332897-79-7C16H18N4OS
- 3-tert-Butyl-6-[(E)-2-(2-methoxyphenyl)ethenyl]-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole876886-77-0C16H18N4OS
- N-(5,6-Dimethylbenzo[d]thiazol-2-yl)-1-isopropyl-1H-pyrazole-3-carboxamide1203031-36-0C16H18N4OS
- 3-((3-Methylbenzyl)thio)-5-propyl-[1,2,4]triazolo[4,3-a]pyrimidin-7(8H)-one891124-20-2C16H18N4OS
- 3-((2-Methylbenzyl)thio)-5-propyl-[1,2,4]triazolo[4,3-a]pyrimidin-7(8H)-one891124-04-2C16H18N4OS
- 3-((2,5-Dimethylbenzyl)thio)-5,6-dimethyl-[1,2,4]triazolo[4,3-a]pyrimidin-7(8H)-one891132-86-8C16H18N4OS
- 6-Cyclohexyl-3-(4-methoxyphenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole840518-53-8C16H18N4OS
- 4-(3-Cyclohexyl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-yl)phenyl methyl ether577765-51-6C16H18N4OS
- 3-Cyclohexyl-6-(3-methoxyphenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole577998-47-1C16H18N4OS
- 3-Cyclohexyl-6-(2-methoxyphenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole846584-17-6C16H18N4OS
- 1-Methyl-N-[(2E)-5-(2-methylpropyl)-1,3,4-thiadiazol-2(3H)-ylidene]-1H-indole-6-carboxamide1219550-13-6C16H18N4OS
- N-(1H-Indol-6-yl)-2-(isobutylamino)-1,3-thiazole-4-carboxamide1219567-89-1C16H18N4OS
- N-(5-Butyl-1,3,4-thiadiazol-2-yl)-1-methyl-1H-indole-6-carboxamide1219562-32-9C16H18N4OS
- N-(1H-Indol-5-yl)-2-(isobutylamino)-1,3-thiazole-4-carboxamide1219566-90-1C16H18N4OS
- 1-Methyl-N-[(2E)-5-(2-methylpropyl)-1,3,4-thiadiazol-2(3H)-ylidene]-1H-indole-5-carboxamide1219562-68-1C16H18N4OS
- 2-(8-tert-Butyl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepin-3-yl)phenyl methyl ether875005-75-7C16H18N4OS
- 4-tert-Butyl-N-(pyrimidin-2-ylcarbamothioyl)benzamide1022582-57-5C16H18N4OS
- N-Cyclopentyl-2-(6-pyridin-3-ylpyridazin-3-yl)sulfanylacetamide872701-46-7C16H18N4OS
- N-(2-(Cyclohex-1-en-1-yl)ethyl)-2-(pyrazin-2-yl)thiazole-4-carboxamide1235629-16-9C16H18N4OS
- N-(3-(1H-Pyrrolo[2,3-b]pyridin-1-yl)propyl)-2,4-dimethylthiazole-5-carboxamide1795410-29-5C16H18N4OS
- 1-(3-(1H-Pyrrolo[2,3-b]pyridin-1-yl)propyl)-3-(thiophen-2-ylmethyl)urea1797261-94-9C16H18N4OS
- N-(2-(1H-Imidazo[1,2-b]pyrazol-1-yl)ethyl)-2-(ethylthio)benzamide1788532-86-4C16H18N4OS
- 2-(Methylthio)-N-(1-(pyridin-2-yl)pyrrolidin-3-yl)nicotinamide1798513-65-1C16H18N4OS
- N-(1-(Pyridin-2-yl)pyrrolidin-3-yl)-2-(pyridin-4-ylthio)acetamide1788557-42-5C16H18N4OS
- N-(2-(Methylthio)phenyl)-6-(pyrrolidin-1-yl)pyrimidine-4-carboxamide2034474-67-2C16H18N4OS
- 3-((4-Methylbenzyl)thio)-5-propyl-[1,2,4]triazolo[4,3-a]pyrimidin-7(8H)-one891124-36-0C16H18N4OS
- N-(2-(3-(Allylsulfanyl)-6-methyl-1,2,4-triazin-5-yl)vinyl)-4-methoxyaniline477865-89-7C16H18N4OS
- N-(2-(2-(m-Tolyl)thiazolo[3,2-b][1,2,4]triazol-6-yl)ethyl)propionamide894036-03-4C16H18N4OS
- N-Cyclopropyl-2-[(2,6-dimethylquinolin-4-yl)carbonyl]hydrazinecarbothioamide847472-87-1C16H18N4OS
- 2-(4-Morpholinyl)ethyl [1,2,4]triazolo[4,3-a]quinolin-1-yl sulfide698968-32-0C16H18N4OS
- N-(2-(1H-Pyrazol-1-yl)ethyl)-N-(4,6-dimethylbenzo[d]thiazol-2-yl)acetamide1169978-41-9C16H18N4OS
- 3-(1H-Indol-1-yl)-N-[(2Z)-5-(propan-2-yl)-1,3,4-thiadiazol-2(3H)-ylidene]propanamide1219578-71-8C16H18N4OS
- N-(5-Butyl-1,3,4-thiadiazol-2-yl)-1-methyl-1H-indole-5-carboxamide1219564-08-5C16H18N4OS
- 1-Methyl-N-[(2E)-5-(2-methylpropyl)-1,3,4-thiadiazol-2(3H)-ylidene]-1H-indole-2-carboxamide1219557-03-5C16H18N4OS
- N-(3-(1H-Pyrrol-1-yl)propyl)-4-methyl-2-(1H-pyrrol-1-yl)thiazole-5-carboxamide1226448-59-4C16H18N4OS
- N-(Benzo[c][1,2,5]thiadiazol-4-yl)-4-(2,5-dimethyl-1H-pyrrol-1-yl)butanamide1251633-22-3C16H18N4OS
- 1-Ethyl-3-methyl-6-(4-methylbenzyl)-5-thioxo-1,4,5,6-tetrahydro-7H-pyrazolo[4,3-d]pyrimidin-7-one1313814-69-5C16H18N4OS
- 2-(4-Methyl-1H-indol-1-yl)-N-[(2E)-5-(propan-2-yl)-1,3,4-thiadiazol-2(3H)-ylidene]acetamide1282140-65-1C16H18N4OS
- 2-Methyl-N-(1-methyl-1H-benzimidazol-5-yl)-5-(propan-2-yl)-1,3-thiazole-4-carboxamide1374537-04-8C16H18N4OS
- 2,4-Dimethyl-N-[2-(propan-2-yl)-1H-benzimidazol-6-yl]-1,3-thiazole-5-carboxamide1401594-39-5C16H18N4OS
- N-{4-[Benzyl(methyl)amino]but-2-yn-1-yl}-4-methyl-1,2,3-thiadiazole-5-carboxamide1396800-47-7C16H18N4OS
- 1-Ethyl-1-(imidazo[1,2-a]pyridin-3-ylmethyl)-3-(thiophen-2-ylmethyl)urea1448034-32-9C16H18N4OS
- 2-Methyl-N-(1-methyl-1H-benzimidazol-5-yl)-4-(propan-2-yl)-1,3-thiazole-5-carboxamide1574295-18-3C16H18N4OS
- 4-((4-(Benzo[d]isothiazol-3-yl)piperazin-1-yl)methyl)-5-methylisoxazole2034339-57-4C16H18N4OS
- (E)-1-((1R,5S)-3-(1H-1,2,4-Triazol-1-yl)-8-azabicyclo[3.2.1]octan-8-yl)-3-(thiophen-2-yl)prop-2-en-1-one2321333-04-2C16H18N4OS
- 3-(Methoxymethyl)-6-(5,6,7,8-tetrahydronaphthalen-2-ylmethyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole903184-20-3C16H18N4OS
- N-(2-(2-(o-Tolyl)thiazolo[3,2-b][1,2,4]triazol-6-yl)ethyl)propionamide941950-59-0C16H18N4OS
- N-(Benzo[d]thiazol-2-yl)-N-(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)acetamide1171705-53-5C16H18N4OS
- N-(1-Cyanocyclopentyl)-2-[(2-methyl-1,3-benzothiazol-6-yl)amino]acetamide1211091-32-5C16H18N4OS
- N-(1-Cyano-1,2-dimethylpropyl)-2-(phthalazin-1-ylsulfanyl)acetamide1211162-92-3C16H18N4OS
- 2-(Methylsulfanyl)-N-[2-(pyrrolidin-1-yl)pyridin-3-yl]pyridine-3-carboxamide1223248-73-4C16H18N4OS
- 2-(3-(Morpholinomethyl)imidazo[2,1-b]thiazol-6-yl)aniline1056562-54-9C16H18N4OS
- 4-Methyl-N-[1-(2-methylpropyl)-1H-indol-4-yl]-1,2,3-thiadiazole-5-carboxamide1374533-18-2C16H18N4OS
- N-(2-(Methylthio)phenyl)-6-(pyrrolidin-1-yl)pyridazine-3-carboxamide1396881-46-1C16H18N4OS
- 4-[(3,5-Dimethyl-1H-pyrazol-1-yl)carbonyl]-5-propyl-2-(1H-pyrrol-1-yl)-1,3-thiazole1707586-34-2C16H18N4OS
- 4-[(3,5-Dimethyl-1H-pyrazol-1-yl)carbonyl]-5-isopropyl-2-(1H-pyrrol-1-yl)-1,3-thiazole1774901-16-4C16H18N4OS
- N-(2-(1H-Imidazo[1,2-b]pyrazol-1-yl)ethyl)-3-(phenylthio)propanamide1790196-20-1C16H18N4OS
- 4-Methyl-N-(3-{2-methylpyrazolo[1,5-a]pyrimidin-6-yl}propyl)thiophene-2-carboxamide1797183-24-4C16H18N4OS
- N-(2-(6-Methyl-1H-imidazo[1,2-b]pyrazol-1-yl)ethyl)-2-(methylthio)benzamide2034238-21-4C16H18N4OS
- N-(3-Methyl-1-(2H-1,2,3-triazol-2-yl)butan-2-yl)benzo[b]thiophene-2-carboxamide2034267-55-3C16H18N4OS
- 2-(Benzylthio)-1-(3-(pyrimidin-2-ylamino)azetidin-1-yl)ethanone2034285-22-6C16H18N4OS
- (2-(Ethylthio)phenyl)(3-(pyrimidin-2-ylamino)azetidin-1-yl)methanone2034420-22-7C16H18N4OS
- (4-(6-Cyclopropylpyridazin-3-yl)piperazin-1-yl)(thiophen-3-yl)methanone2034493-60-0C16H18N4OS
- 3-(Phenylthio)-1-(3-(pyrimidin-2-ylamino)azetidin-1-yl)propan-1-one2309629-55-6C16H18N4OS
- (3-(4-Cyclopropyl-1H-1,2,3-triazol-1-yl)azetidin-1-yl)(3-(methylthio)phenyl)methanone2097860-18-7C16H18N4OS
- N-(1-(1,2,5-Thiadiazol-3-yl)piperidin-4-yl)cinnamamide2035036-64-5C16H18N4OS
- 1-((5-Cyclopropylpyridin-3-yl)methyl)-3-(4-cyclopropylthiazol-2-yl)urea2034539-80-3C16H18N4OS
- 2-(Benzylsulfanyl)-1-{3-[(pyrazin-2-yl)amino]azetidin-1-yl}ethan-1-one2310017-38-8C16H18N4OS
- Thiazolo(2,3-c)-1,2,4-triazol-5(6H)-one, 6-((4-(diethylamino)phenyl)methylene)-3-methyl-95356-80-2C16H18N4OS
Frequently asked questions
What is the molar mass of C16H18N4OS?
The molar mass of C16H18N4OS is 314.41 g/mol, calculated from standard atomic weights for 16 carbon atoms, 18 hydrogen atoms, 4 nitrogen atoms, 1 oxygen atom and 1 sulfur atom. The monoisotopic mass is 314.1201 Da.
How many compounds have the formula C16H18N4OS?
CompoundList lists 155 compounds with the molecular formula C16H18N4OS, including 1-[[Oxo(3-pyridinyl)methyl]amino]-3-(4-propan-2-ylphenyl)thiourea, (1E)-4,4,6,8-Tetramethyl-4H-pyrrolo[3,2,1-ij]quinoline-1,2-dione 1-thiosemicarbazone, N-Cyclopentyl-2-[[6-(2-pyridinyl)-3-pyridazinyl]thio]acetamide. 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 C16H18N4OS?
C16H18N4OS has a degree of unsaturation of 10. 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.