Elemental carbon in the sp1 hybridization

Abstract

Hybridizations of carbon atoms are textbook examples of different types of chemical bonds. Likewise, the elemental phases of carbon, graphite and diamond are well known as materials in pure sp2 or sp3 hybridizations. However, what is much less known is the elemental carbon phase in the sp1 (or sp) hybridization. The phase is called carbyne and still somewhat elusive, although many reports on successful syntheses have been given. Carbyne is assumed to consist of densely packed linear chains of carbon atoms and appears to be a rather unstable material. Individual chains of carbon atoms are perfectly one-dimensional structures and show many highly interesting physical properties of classical 1D materials. This article first gives an overview of the relation between the differently hybridized elemental phases of carbon and then focuses on the structure and the properties of individual sp1 chains of carbon atoms. A brief survey of the synthesis of individual carbon chains as well as bulk carbyne is given at the end of the article.