Molecular formula
C18H19N5O3
212 compounds have this formula on CompoundList.
- Molar mass
- 353.38g/mol
- Monoisotopic mass
- 353.1488Da
- Atoms
- 45
- Elements
- 4
- Rings plus double bonds
- 12
The formula C18H19N5O3 describes a molecule made of 18 carbon atoms, 19 hydrogen atoms, 5 nitrogen atoms and 3 oxygen atoms. 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 × 1861.18%12.011 × 18 = 216.198 g/mol
- H Hydrogen × 195.42%1.008 × 19 = 19.152 g/mol
- N Nitrogen × 519.82%14.007 × 5 = 70.035 g/mol
- O Oxygen × 313.58%15.999 × 3 = 47.997 g/mol
Look up another formula
Compounds with the formula C18H19N5O3
Isomers we list, best known first. Open one to see its structure, properties, safety data and suppliers.
Showing 1 to 100 of 212 compounds
2-Cyano-N-ET-3-(2-(4-morpholinyl)4-oxo-4H-pyrido(1,2-A)pyrimidin-3-yl)acrylamide
CAS 477734-66-0C18H19N5O3
3-(1H-1,2,3-Benzotriazol-1-yl)N'-(3-ethoxy-4-hydroxybenzylidene)propanohydrazide
CAS 452089-85-9C18H19N5O3
![N-Allyl-2-imino-1-(2-methoxyethyl)-5-oxo-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide chemical structure, C18H19N5O3, CAS 371923-17-0](/s/LHSDHXKVQLRKQI-UHFFFAOYSA-N.svg)
N-Allyl-2-imino-1-(2-methoxyethyl)-5-oxo-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide
CAS 371923-17-0C18H19N5O3
2-(3,5-Dimethyl-1-pyrazolyl)-4-(4-hydroxyanilino)-5-pyrimidinecarboxylic acid ethyl ester
CAS 958983-98-7C18H19N5O3
![7-[2-(3,4-Dihydro-2H-quinolin-1-yl)-2-oxoethyl]-1,3-dimethylpurine-2,6-dione chemical structure, C18H19N5O3, CAS 314042-95-0](/s/YCLRZABNMYAXCE-UHFFFAOYSA-N.svg)
7-[2-(3,4-Dihydro-2H-quinolin-1-yl)-2-oxoethyl]-1,3-dimethylpurine-2,6-dione
CAS 314042-95-0C18H19N5O3
![7-[2-(3,4-Dihydroisoquinolin-2(1H)-yl)-2-oxoethyl]-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione chemical structure, C18H19N5O3, CAS 314042-94-9](/s/HMPCJNGQLRDHFJ-UHFFFAOYSA-N.svg)
7-[2-(3,4-Dihydroisoquinolin-2(1H)-yl)-2-oxoethyl]-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione
CAS 314042-94-9C18H19N5O3
![6-[(4-Methoxyphenoxy)methyl]-N-(2-methoxyphenyl)-1,3,5-triazine-2,4-diamine chemical structure, C18H19N5O3, CAS 669744-43-8](/s/KAMSGKNVDXIKTF-UHFFFAOYSA-N.svg)
6-[(4-Methoxyphenoxy)methyl]-N-(2-methoxyphenyl)-1,3,5-triazine-2,4-diamine
CAS 669744-43-8C18H19N5O3
Cgp-15720
CAS 73998-69-3C18H19N5O3
3-(1H-1,2,3-Benzotriazol-1-yl)-N'-(3,4-dimethoxybenzylidene)propanohydrazide
CAS 326002-01-1C18H19N5O3
![1,3-Dimethyl-7-[2-(2-methyl-2,3-dihydroindol-1-yl)-2-oxoethyl]purine-2,6-dione chemical structure, C18H19N5O3, CAS 849457-68-7](/s/BHZGNLRWZGRHJE-UHFFFAOYSA-N.svg)
1,3-Dimethyl-7-[2-(2-methyl-2,3-dihydroindol-1-yl)-2-oxoethyl]purine-2,6-dione
CAS 849457-68-7C18H19N5O3
3-(1H-1,2,3-Benzotriazol-1-yl)-N'-(2,5-dimethoxybenzylidene)propanohydrazide
CAS 612047-68-4C18H19N5O3
Disperse dye (C.I. 11230)
CAS 6054-58-6C18H19N5O3
2-(1H-1,2,3-Benzotriazol-1-yl)-N'-(3,4-dimethoxybenzylidene)propanohydrazide
CAS 354542-45-3C18H19N5O3
![3-[(4-Ethoxyphenyl)diazenyl]-5,6,7,8-tetrahydropyrazolo[5,1-b]quinazoline-2,9(1H,4H)-dione chemical structure, C18H19N5O3, CAS 791826-17-0](/s/TUVGGOUTPMPAFJ-UHFFFAOYSA-N.svg)
3-[(4-Ethoxyphenyl)diazenyl]-5,6,7,8-tetrahydropyrazolo[5,1-b]quinazoline-2,9(1H,4H)-dione
CAS 791826-17-0C18H19N5O3
![N-[2-(4-Methoxyphenyl)ethyl]-2-[3-(tetrazol-1-yl)phenoxy]acetamide chemical structure, C18H19N5O3, CAS 872212-30-1](/s/RJESJYWCDOZYHH-UHFFFAOYSA-N.svg)
N-[2-(4-Methoxyphenyl)ethyl]-2-[3-(tetrazol-1-yl)phenoxy]acetamide
CAS 872212-30-1C18H19N5O3
3-(1H-1,2,3-Benzotriazol-1-yl)-N'-(1-(4-HO-3-meo-PH)ethylidene)propanohydrazide
CAS 518019-33-5C18H19N5O3
![4-(2,3,4-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine chemical structure, C18H19N5O3, CAS 727686-81-9](/s/BRFPKZILQHSRTP-UHFFFAOYSA-N.svg)
4-(2,3,4-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine
CAS 727686-81-9C18H19N5O3
![4-(3,4,5-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine chemical structure, C18H19N5O3, CAS 306735-68-2](/s/OTHLDBRZPXOSIW-UHFFFAOYSA-N.svg)
4-(3,4,5-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine
CAS 306735-68-2C18H19N5O3
1,3-Dimethyl-9-(2-PH-ET)-6,7-dihydropyrimido(2,1-F)purine-2,4,8(1H,3H,9H)-trione
CAS 476481-03-5C18H19N5O3
![8-(4-Hydroxybutyl)-1-methyl-7-phenyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione chemical structure, C18H19N5O3, CAS 633281-74-0](/s/JOEYVYNGBCYTGH-UHFFFAOYSA-N.svg)
8-(4-Hydroxybutyl)-1-methyl-7-phenyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione
CAS 633281-74-0C18H19N5O3
![4-(2,4,5-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine chemical structure, C18H19N5O3, CAS 774560-41-7](/s/BEDYPXZLBGYYGV-UHFFFAOYSA-N.svg)
4-(2,4,5-Trimethoxyphenyl)-1,4-dihydro[1,3,5]triazino[1,2-a]benzimidazol-2-amine
CAS 774560-41-7C18H19N5O3
![5-[2-(3,4-Dihydro-2H-quinolin-1-yl)-2-oxoethyl]-1-(2-hydroxyethyl)pyrazolo[3,4-d]pyrimidin-4-one chemical structure, C18H19N5O3, CAS 900011-24-7](/s/HYTQZPJGPNBAJJ-UHFFFAOYSA-N.svg)
5-[2-(3,4-Dihydro-2H-quinolin-1-yl)-2-oxoethyl]-1-(2-hydroxyethyl)pyrazolo[3,4-d]pyrimidin-4-one
CAS 900011-24-7C18H19N5O3
3-(4-Methoxyphenyl)-N-(2-morpholinopyrimidin-4-yl)isoxazol-5-amine
CAS 2408648-20-2C18H19N5O3
3-(3,5-Dimethylisoxazol-4-yl)-1-(3-(3-(pyridin-2-yl)-1,2,4-oxadiazol-5-yl)azetidin-1-yl)propan-1-one
CAS 1251552-15-4C18H19N5O3
- N-(3-Methoxyphenyl)-2-{1-oxo-1H,2H,7H,8H,9H,10H-[1,2,4]triazino[4,5-b]indazol-2-yl}acetamide1021216-99-8C18H19N5O3
- 2,6-Dihydro-2-(3-(dimethylamino)propyl)-5-nitropyrazolo(3,4,5-kl)acridin-9-ol99009-18-4C18H19N5O3
- N,N-Dimethyl-9-methoxy-5-nitropyrazolo(3,4,5-kl)acridine-2(6H)-ethanamine99008-57-8C18H19N5O3
- 2-(2-Methoxyethyl)-4,7-dimethyl-6-phenylpurino[7,8-a]imidazole-1,3-dione900273-47-4C18H19N5O3
- N-(4-Ethoxyphenyl)-5-[(4-methoxyphenyl)amino]-1H-1,2,3-triazole-4-carboxamide1021207-28-2C18H19N5O3
- Ethyl (5-(acetylamino)-1,2-dihydro-3-phenylpyrido(3,4-b)pyrazin-7-yl)carbamate87607-28-1C18H19N5O3
- N-[(5-{1-[(3Z)-5-(carbamoylamino)-2-oxo-2,3-dihydro-1H-indol-3-ylidene]ethyl}-1H-pyrrol-3-yl)methyl]acetamide1056225-57-0C18H19N5O3
- 3-Methyl-7-(2-oxo-2-phenylethyl)-8-(pyrrolidin-1-yl)-1H-purine-2,6(3H,7H)-dione716340-75-9C18H19N5O3
- 9-Amino-N-[2-(dimethylamino)ethyl]-5-nitroacridine-4-carboxamide89459-49-4C18H19N5O3
- N-Benzyl-4-nitro-7-piperidin-1-yl-2,1,3-benzoxadiazol-5-amine332163-96-9C18H19N5O3
- 1-Methyl-3-(2-oxopropyl)-8-(m-tolyl)-7,8-dihydro-1H-imidazo[2,1-f]purine-2,4(3H,6H)-dione838884-53-0C18H19N5O3
- 2-Imino-1-methyl-5-oxo-N-((tetrahydrofuran-2-yl)methyl)-2,5-dihydro-1H-dipyrido[1,2-a:2',3'-d]pyrimidine-3-carboxamide797796-35-1C18H19N5O3
- 1-Methyl-3-(2-oxopropyl)-8-(p-tolyl)-7,8-dihydro-1H-imidazo[2,1-f]purine-2,4(3H,6H)-dione887888-91-7C18H19N5O3
- 6-(2-Methoxy-5-methylphenyl)-4,7,8-trimethylpurino[7,8-a]imidazole-1,3-dione876672-99-0C18H19N5O3
- 2-[(4,6-Dimethylpyrimidin-2-yl)amino]-3-(3-methylphenyl)-6-oxo-3,4,5,6-tetrahydropyrimidine-4-carboxylic acid1009237-10-8C18H19N5O3
- N-(1-(3,4-Dimethylphenyl)-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl)tetrahydrofuran-2-carboxamide899737-97-4C18H19N5O3
- 8-(4-Ethoxyphenyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione896321-53-2C18H19N5O3
- 6-(4-Methoxyphenyl)-4-methyl-2-prop-2-enyl-7,8-dihydropurino[7,8-a]imidazole-1,3-dione352522-69-1C18H19N5O3
- 3-Allyl-8-(furan-2-ylmethyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione896322-24-0C18H19N5O3
- 3-Ethyl-8-(4-methoxyphenyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione877643-97-5C18H19N5O3
- 5-Amino-N-(3,5-dimethoxyphenyl)-1-(4-methylphenyl)-1H-1,2,3-triazole-4-carboxamide1260987-50-5C18H19N5O3
- 8-(4-Methoxybenzyl)-1,3,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione869344-92-3C18H19N5O3
- 8-(2-Methoxyphenyl)-1,3,6,7-tetramethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione878441-25-9C18H19N5O3
- 4-Hydroxy-8-(3-methoxypropyl)-1-methyl-7-phenyl-1H-imidazo[2,1-f]purin-2(8H)-one879436-29-0C18H19N5O3
- 8-(4-Methoxybenzyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione879448-60-9C18H19N5O3
- 8-(Furan-2-ylmethyl)-1,7-dimethyl-3-(2-methylallyl)-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione896850-74-1C18H19N5O3
- 8-(2-Methoxy-5-methylphenyl)-1,3,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione876672-09-2C18H19N5O3
- 1-Methyl-3-(2-oxopropyl)-9-phenyl-6,7,8,9-tetrahydropyrimido[2,1-f]purine-2,4(1H,3H)-dione845662-23-9C18H19N5O3
- 3-Benzyl-8-(2-hydroxyethyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione915931-62-3C18H19N5O3
- 5-Amino-N-(2,4-dimethoxyphenyl)-1-(2-methylphenyl)-1H-1,2,3-triazole-4-carboxamide951893-42-8C18H19N5O3
- N-(2-Methoxyphenyl)-3-(4-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-14-2C18H19N5O3
- 1H-Imidazo(2,1-f)purine-2,4(3H,8H)-dione, 1,3-dimethyl-8-(2-hydroxyethyl)-7-(4-methylphenyl)-96902-24-8C18H19N5O3
- 6-(3-Methoxyphenyl)-4-methyl-2-prop-2-enyl-7,8-dihydropurino[7,8-a]imidazole-1,3-dione893948-53-3C18H19N5O3
- 8-(4-Methoxyphenyl)-1,3,6,7-tetramethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione896849-88-0C18H19N5O3
- 8-(2-Ethoxyphenyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione878732-95-7C18H19N5O3
- 3-Ethyl-8-(3-methoxyphenyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione877643-91-9C18H19N5O3
- (E)-3-(But-2-en-1-yl)-8-(furan-2-ylmethyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione946261-08-1C18H19N5O3
- 5-Amino-N-benzyl-1-(2,5-dimethoxyphenyl)-1H-1,2,3-triazole-4-carboxamide1049126-92-2C18H19N5O3
- 2-[3-(6-Amino-5-cyano-3-propyl-2,4-dihydropyrano[2,3-c]pyrazol-4-yl)phenoxy]acetamide445391-01-5C18H19N5O3
- N-(3-Methoxyphenyl)-3-(4-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-15-3C18H19N5O3
- N,3-bis(3-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-50-6C18H19N5O3
- 3-(2,5-Dimethoxyphenyl)-N-phenyl-2-(2H-tetrazol-5-yl)propanamide483995-12-6C18H19N5O3
- N-(2-Methoxyphenyl)-3-(3-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-48-2C18H19N5O3
- 3-(3-Methoxyphenyl)-N-(4-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-52-8C18H19N5O3
- N,3-bis(2-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-73-3C18H19N5O3
- 3-(2-Methoxyphenyl)-N-(4-methoxyphenyl)-2-(2H-tetrazol-5-yl)propanamide483993-75-5C18H19N5O3
- 6-(2-Ethoxyphenyl)-2,4,7-trimethylpurino[7,8-a]imidazole-1,3-dione878728-36-0C18H19N5O3
- 8-(2-Hydroxyphenyl)-1,7-dimethyl-3-propyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione915926-17-9C18H19N5O3
- 8-(3-Ethoxyphenyl)-1,3,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione949245-11-8C18H19N5O3
- N-(2-{[3-(4-Methoxyphenyl)-[1,2,4]triazolo[4,3-b]pyridazin-6-yl]oxy}ethyl)cyclopropanecarboxamide1060168-58-2C18H19N5O3
- 1,3-Dimethyl-8-(3-prop-2-enyloxyphenyl)-1,3,5-trihydroimidazolidino[1,2-h]puri ne-2,4-dione946225-66-7C18H19N5O3
- (4-(5-Cyclopropyl-1,3,4-oxadiazol-2-yl)piperidin-1-yl)(3-(furan-2-yl)-1H-pyrazol-5-yl)methanone1305342-06-6C18H19N5O3
- 5-(Furan-2-yl)-N-((1-(pyrimidin-2-yl)piperidin-4-yl)methyl)isoxazole-3-carboxamide1235615-71-0C18H19N5O3
- N-(2-(3-Cyclopropyl-5-oxo-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-1-yl)ethyl)-5-methylisoxazole-3-carboxamide1396853-73-8C18H19N5O3
- 4-Methoxy-1-methyl-5-{4-methyl-2,3,7,11-tetraazatricyclo[7.4.0.0^{2,6}]trideca-1(9),3,5,7-tetraene-11-carbonyl}-1,2-dihydropyridin-2-one1798040-67-1C18H19N5O3
- 5-(2-Morpholino-2-oxoethyl)-1-(p-tolyl)-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one841212-03-1C18H19N5O3
- N-(3-Oxo-3,4-dihydro-2H-1,4-benzoxazin-6-yl)-4-(2-pyridinyl)tetrahydro-1(2H)-pyrazinecarboxamide685107-80-6C18H19N5O3
- 8-(2-Hydroxyethyl)-1,3,6-trimethyl-7-phenyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione727662-98-8C18H19N5O3
- 6-(4-Ethoxyphenyl)-2,4,7-trimethylpurino[7,8-a]imidazole-1,3-dione876901-54-1C18H19N5O3
- 3-(2-Methoxyphenyl)-N-(3-methoxyphenyl)-2-(2H-1,2,3,4-tetrazol-5-yl)propanamide483993-74-4C18H19N5O3
- 8-(3-Methoxyphenyl)-1,3,6,7-tetramethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione896806-94-3C18H19N5O3
- Ethyl 2-[(6-methoxy-4-methylquinazolin-2-yl)amino]-4-methylpyrimidine-5-carboxylate903446-21-9C18H19N5O3
- 3-Ethyl-8-(2-methoxyphenyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione887465-98-7C18H19N5O3
- 3-Ethyl-8-(2-hydroxyphenyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione915932-43-3C18H19N5O3
- N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-3-(6,8-dimethyl[1,2,4]triazolo[4,3-b]pyridazin-7-yl)propanamide932518-20-2C18H19N5O3
- N-(2-Ethoxyphenyl)-5-[(4-methoxyphenyl)amino]-1H-1,2,3-triazole-4-carboxamide1207033-46-2C18H19N5O3
- 2-[(4-Hydroxyquinolin-3-yl)formamido]-N-[1-(1H-pyrazol-1-yl)propan-2-yl]acetamide1223627-48-2C18H19N5O3
- N-(2-{[2-(5-Methoxy-1H-indol-1-yl)ethyl]amino}-2-oxoethyl)-2-pyrazinecarboxamide1374535-62-2C18H19N5O3
- N-(2-{[2-(5-Methoxy-1H-indol-3-yl)ethyl]amino}-2-oxoethyl)-2-pyrazinecarboxamide1374545-03-5C18H19N5O3
- N-{3-[2-(3,4-Dimethoxyphenyl)ethyl]-1H-1,2,4-triazol-5-yl}pyridine-4-carboxamide1574493-94-9C18H19N5O3
- N-{3-[2-(3,4-Dimethoxyphenyl)ethyl]-1H-1,2,4-triazol-5-yl}pyridine-2-carboxamide1574463-67-4C18H19N5O3
- N-{3-[2-(3,4-Dimethoxyphenyl)ethyl]-1H-1,2,4-triazol-5-yl}pyridine-3-carboxamide1574493-02-9C18H19N5O3
- N-[3-(2-Methoxyethyl)-4-oxo-3,4-dihydroquinazolin-6-yl]-2,4,5,6-tetrahydrocyclopenta[c]pyrazole-3-carboxamide1574391-79-9C18H19N5O3
- N-(2,4-Dimethoxyphenyl)-2-[5-(4-methylphenyl)tetrazol-2-yl]acetamide445412-43-1C18H19N5O3
- 1,3-Dimethyl-8-phenethyl-8,9-dihydropyrazino[2,1-f]purine-2,4,7(1H,3H,6H)-trione878420-81-6C18H19N5O3
- 1-(2-Methylphenyl)-5-(2-morpholin-4-yl-2-oxoethyl)pyrazolo[3,4-d]pyrimidin-4-one887456-81-7C18H19N5O3
Frequently asked questions
What is the molar mass of C18H19N5O3?
The molar mass of C18H19N5O3 is 353.38 g/mol, calculated from standard atomic weights for 18 carbon atoms, 19 hydrogen atoms, 5 nitrogen atoms and 3 oxygen atoms. The monoisotopic mass is 353.1488 Da.
How many compounds have the formula C18H19N5O3?
CompoundList lists 212 compounds with the molecular formula C18H19N5O3, including 2-Cyano-N-ET-3-(2-(4-morpholinyl)4-oxo-4H-pyrido(1,2-A)pyrimidin-3-yl)acrylamide, 3-(1H-1,2,3-Benzotriazol-1-yl)N'-(3-ethoxy-4-hydroxybenzylidene)propanohydrazide, N-Allyl-2-imino-1-(2-methoxyethyl)-5-oxo-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide. 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 C18H19N5O3?
C18H19N5O3 has a degree of unsaturation of 12. 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.