Heterocumulene
Heterocumulenes are molecules consisting of a linear chain of carbon atoms with one or more of another atom attached to the end. The carbon atoms are all joined joined by double bonds C=C=C=C. Similar molecules termed cumulenic, have a chain of alternating triple and single bonds. C≡C-C≡C-.... Heterocumulenes are found in space or flames.
Reactions
Some energised herterocumulenes can cyclise by bending into a circle and bonding the two ends of the chain. Molecules that can do this are CCCB, CCCAl, CCCSi, CCCN, or CCCP.[1]
Other four atom heterocumulenes include CCBO, tricarbon monoxide (CCCO) and CCCS Four atom heterocumulenes when cyclised can have two forms. In the kite (or rhombic) form, a triangle of carbon has two of its atoms bonded to the heteroatom. In the fan form the hetero atom links to three carbon atoms arranged in a fan shape. CCCSi has linear, rhombic or fan isomers. The rhombic form is known is space near the carbon star IRC+10216.
CCCCO cyclises to a three member ring.[1] CCCCN undergoes an isonitrile conversion.[1]
Other known five atom heterocumulenes include CCBCC, CCCCB, CCOCC, CCCCSi, CNCCO, HCCCO, HCCCS, NCCCN CCCCSi is known as a linear molecule in space.
CCCCBO turns into a six member ring. Other six atom heterocumulenes include OCCCCN and HCNCNH.
Seven atom heterocumulenes include NCCCCCN, HCCBCCH.
A known nine atom heterocumulene is HCCCCCCCH.
References
- 1 2 3 Wang, Tianfang; Bowie, John H. (November 2011). "Studies of cyclization reactions of linear cumulenes and heterocumulenes using the neutralization-reionization procedure and/or ab initio calculations". Mass Spectrometry Reviews. 30 (6): 1225–1241. doi:10.1002/mas.20328.