Preferred IUPAC Names 73 Chapter 2, Sect 25 September, 2004 P-25 Fused and bridged fused systems P-25.0 Introduction P-25.1 Names of hydrocarbon components P-25.2 Names of heterocyclic components P-25.3 Constructing fusion names P-25.4 Bridged fused systems P-25.5 Limitations to fusion nomenclature: three components ortho- and peri- fused together P-25.6 Heteroatoms in nonstandard valence states P-25.7 Treatment of double bonds and δ-convention P-25.8 List of fusion components in decreasing order of seniority P-25.0 Introduction This section is based on the document entitled ‘Nomenclature of Fused and Bridged Fused Ring System, IUPAC Recommendations 1998’ (ref. 4). In nomenclature, fusion is the operation that creates a common bond between two rings, each ring contributing one bond and the two atoms directly attached to the bond. This type of fusion is called ortho- or ortho- and peri-fusion if two adjacent bonds are involved. The term fusion is also used todesc ribe the operation creating a common atom between two ring systems, each contributing one atom. This type of fusion is called spirofusion (see P-24.1). Traditionally, ortho- and ortho- and peri-fusion were simply called fusion and the resulting polycyclic systems were referred to as fused ring systems or fused ring compounds. The term 'spirofusion' is new in nomenclature, and to avoid ambiguity 'fusion' should not be used without the prefix 'spiro' when 'spirofusion' is intended." CH HC C + CH HC C benzene (PIN) benzene (PIN) naphthalene (PIN) [naphthalene results from the fusion (ortho-fusion) of two benzene rings (one bond and two atoms in common)] IUPAC Provisional Recommendations Page 1 of 92 DRAFT 7 October 2004 Preferred IUPAC Names 74 Chapter 2, Sect 25 September, 2004 H CH C C C + HC C CH C C CH2 H 1 naphthalene (PIN) benzene (PIN) 1H-phenalene (PIN) [1H-phenalene results from the fusion (ortho- and peri-fusion) of a naphthalene ring system and a benzene ring (two bonds and three atoms in common] 1 H C CH + 2 C 2 1 indene (PIN) indene (PIN) 1,1′-spirobi[indene] (PIN) [spiro[biindene] results from the spirofusion of two indene ring systems (one atom in common)] This section deals with fused (ortho- and ortho- and peri-fused) ring systems and bridged fused (ortho- and ortho- and peri-fused) ring systems. Spirofusion is described in Section P-24. This section is intended only as an introduction to the vast field of fusion nomenclature discussed in the document entitled ‘Nomenclature of Fused and Bridge Fused Ring Systems’ (ref. 4). The principles presented herein use rather simple examples; for more complex ring systems the publication noted above or the ‘Ring Systems Handbook’, published by the Chemical Abstracts Service (ref. 16), should be consulted. Changes from previous rules are highlighted. P-25.1 Names of hydrocarbon parent compounds are divided into two categories. P-25.1.1 Retained names used for parent components and as attached components P-25.1.2 Names formed systematically using endings and prefixes used for parent components and as attached components P-25.1.1 Retained names for hydrocarbons (also called trivial names) used for parent components and for attached components Retained names for polycyclic hydrocarbons are listed in Table 2.7, in decreasing order of seniority for being chosen as parent components in fusion nomenclature. Their numbering is indicated as the result of the application of the specific criteria used to number fused ring systemsIUPAC described in SectionProvisional P-25.3.3. Recommendations DRAFT 7 October 2004 Page 2 of 92 Preferred IUPAC Names 75 Chapter 2, Sect 25 September, 2004 Table 2.7 Retained names of hydrocarbon parent components in descending order of seniority (the senority order is indicated by the number preceding the name; the lower the number the higher the senority) 13 14 1 15 16 1 13a 14a 15a 16a 12 2 14 2 11a 13a1 14a1 2a 13a 1 4b1 2a1 13a 3 11 3 13 1 4a 11a 13a2 4b 4 2 1 12 6a 4a 12b 7a1 5a1 10 4 12a 5 9a1 11 9a 7a1 6a1 4a 5a 9 5 10 6 7a 6a 8a 7a 8 7 6 7 9 8 (1) ovalene (PIN) (2) pyranthrene (PIN) 12 1 2 12a 3 11 2 1 3a 4 10a 12a1 2a 14 1 13 14c 10a 5 10 3 14a 3b 2a1 3a1 1 12 14b 8a 6 9 4 7b 7a 1 7 8a 6a1 4a 4a 11 10b 7c1 7c 10a 8 5 8 6a 10 7 6 9 (3) coronene (PIN) (4) rubicene (PIN) 2 2 1 3 1 3 12 12b 3a 14 14b 12a 14a 11 4 13 4 3a1 4a 12 6b1 12b 5 12a 5 10 11 6a 6a 9a 6b 6 6b 6 9 7 10 7 8a 8 9 8 (5) perylene (PIN) (6) picene (PIN) 1 2 12 1 12a 12 11 12a 11 2 11a 3 10 10 10b 10a 3a 3 9 4a 4b 9 4 4 7a 6a 8 7 8 5 6a 6 5 7 6 (7) pleiadene (PIN) (8) chrysene (PIN) IUPAC Provisional Recommendations Page 3 of 92 DRAFT 7 October 2004 Preferred IUPAC Names 76 Chapter 2, Sect 25 September, 2004 Table 2.5 (cont'd.) 10 1 1 2 10a 9 2 10 10b 10a 3 8a 3a1 9 3 8 3a 5a1 3a 8 4 6b 6a 7 4 7 5a 6 5 6 5 (9) pyrene (PIN) (10) fluoranthene (PIN) 8 9 1 3 8a 9a 7 2 4 2 5 4a 3 4b 1 6 6 10a 4a 10a 5 10 4 7 10 8a 9 8 (11) anthracene (PIN) (12) phenanthrene (PIN) (special numbering) (special numbering) 2 1 3 9 8 1 9a 3a CH 7 2 2 9 4 3a1 6 3 8 5 4b 4a 6a 5 4 7 6 (13) phenalene (PIN) (14) fluorene (PIN) (1H-isomer shown) (9H-isomer shown) 1 2 8 7 7a 8a 1 8b 8 8a 3 3a 6 2 7 4 5 4a 3a 3 4 6 5a 5 (15) s-indacene (PIN) (16) as-indacene (PIN) 8 1 8 1 7 8a 8a 7 2 6 2 6 3 3a 4a 5 3 5 4 4 (17) azulene (PIN) (18) naphthalene (PIN) IUPAC Provisional Recommendations DRAFT 7 October 2004 Page 4 of 92 Preferred IUPAC Names 77 Chapter 2, Sect 25 September, 2004 Table 2.5 (cont'd.) 1 7 7a CH 6 2 2 5 3a 3 4 (19) indene (PIN) (1H-isomer shown) P-25.1.2 Systematically named hydrocarbon parent components Names for some hydrocarbon parent components, having the maximum number of noncumulated double bonds and having at least two rings of five or more ring members are systematically formed using a prefix and an ending or term representing the nature and arrangement of the component rings. Rules for numbering are described in Section P-25.3.3. P-25.1.2.1 Polyacenes P-25.1.2.2 Polyaphenes P-25.1.2.3 Polyalenes P-25.1.2.4 Polyphenylenes P-25.1.2.5 Polynaphthylenes P-25.1.2.6 Polyhelicenes P-25.1.2.7 Ace...ylenes P-25.1.2.1 Polyacenes. A hydrocarbon parent component consisting of four or more ortho- fused benzene rings in a straight linear arrangement is named by citing a numerical prefix (‘tetra’, ‘penta’, etc.) denoting the number of rings followed by the ending ‘acene’ (derived from the retained name anthracene) with elision of a letter ‘a’. Examples: 1 1 2 2 tetracene (PIN) pentacene (PIN) (formerly naphthacene) P-25.1.2.2 Polyaphenes. A hydrocarbon parent component consisting of n ortho-fused benzene rings (n > 3) forming two straight linear arrangements of (n + 1)/2 rings (if n is odd) or n/2 and (n/2) + 1 rings (if n is even) with a common benzene ring and that make a formal angle of 120° with each other is named by citing the numerical prefix (‘tetra’, ‘penta’, etc.) denoting the total number of benzene rings followed by the ending ‘phene’ (derived from phenanthrene). Example:IUPAC Provisional Recommendations Page 5 of 92 DRAFT 7 October 2004 Preferred IUPAC Names 78 Chapter 2, Sect 25 September, 2004 2 2 common ring 1 1 common ring (n+1)/2 rings n/2 rings (n+1)/2 rings n/2 + 1 rings pentaphene (n = 5) (PIN) hexaphene (n = 6) (PIN) P-25.1.2.3 Polyalenes. A hydrocarbon parent component consisting of two identical ortho- fused monocyclic hydrocarbon rings is named by citing the numerical prefix (‘penta’, ‘hepta’, etc.) that denotes the number of carbon atoms in each ring followed by the ending ‘alene’ (derived from naphthalene) with elision of a letter ‘a’. The name naphthalene is retained. Examples: 1 2 1 2 pentalene (PIN) octalene (PIN) P-25.1.2.4 Polyphenylenes. A hydrocarbon parent component consisting of a monocyclic hydrocarbon with an even number of carbon atoms and benzene rings ortho-fused to alternate sides is named by citing a numerical prefix (‘tri’, ‘tetra’, etc.) denoting the number of benzene rings followed by the term ‘phenylene’. The traditional name biphenylene is retained. Examples: 2 1 1 2 biphenylene (PIN) triphenylene (PIN) (not diphenylene) IUPAC Provisional Recommendations DRAFT 7 October 2004 Page 6 of 92 Preferred IUPAC Names 79 Chapter 2, Sect 25 September, 2004 P-25.1.2.5 Polynaphthylenes. A hydrocarbon parent component that consists of a monocyclic hydrocarbon with an even number of carbon atoms ortho-fused on alternate sides to the 2,3-positions of naphthalene rings is named by citing a numerical prefix (‘tri’, ‘tetra’, etc.) denoting the number of naphthalene rings followed by the term ‘naphthylene’.