Growth and Photodissociation of Cr_x−(Coronene)_y Complexes

Abstract

Gas-phase complexes are produced containing one or more chromium atoms bound to one or more molecules of the polycyclic aromatic hydrocarbon (PAH) coronene (C24H12). These species are prepared with laser vaporization in a pulsed-nozzle cluster source of a chromium rod coated with a thin film of coronene. Mass spectroscopy reveals the formation of clusters of the form Cr x (coronene) y + up to sizes with x = 5 and y = 3. Mass-selected laser photodissociation studies investigate the possible structural patterns in these novel complexes. Evidence is presented for multiple metal attachment on the same side of the coronene molecule, for metal and multimetal sandwich structures, and for multiple decker sandwich structures. Chromium atom insertion into the aromatic system is observed for several cluster sizes. Complexes with at least four chromium atoms fragment by extensive decomposition of the aromatic ring system.

Photoelectron spectroscopic and theoretical studies of Fem−(coronene)n (m=1,2, n=1,2) complexes

“…Although the bond length between the metal atoms varies, they should not be considered as completely dispersed atoms. Thus, the structure proposed before, 33 with metal atoms binding to the alternate rings of coronene, may not always be the case.…”

“…Thus, together, our experimental and computational results provide evidence for the existence of sandwich structures for transition metal-coronene complexes. In an earlier work by Foster et al, 33 the authors proposed a staggered sandwich structure as a possible structure for Cr 1 ͑coronene͒ 2 + . The metal binding was thought to transfer charge to both rings, giving the coronene rings similar charge densities, which in turn caused the two coronene molecules to rotate away from one another and to form a staggered configuration.…”

Computational study of adsorption of cobalt on benzene and coronene

“…We use this molecular system as a prototype for a graphene sheet, where on the hollow site of the central ring, a cobalt atom is introduced as a local defect. Metal-coronene complexes are currently of experimental [61][62][63][64] and theoretical [65,66] interest, because the delocalised π electrons in coronene make it a suitable model system for studying the interaction of metals with extended systems. These papers show that many different metals (TMs and otherwise) can form bound ionic and neutral complexes with coronene.…”

Photoelectron spectroscopy and theoretical studies of [Com(pyrene)n]− (m=1,2 and n=1,2) complexes

“…Dunbar 10 and Pozniak and Dunbar 42 generated several different metals reacting with one or more coronene molecules. Duncan and co-workers reported photodissociation studies for positively charged metal-coronene systems, 3,[7][8][9]13,14,44 Nb-, Fe-, and Ca-pyrene systems, 13,44,45 and metal-corannulene complexes, 4 as well as the photoelectron spectroscopic studies ͑with Nakajima͒ for V-and Ti-coronene cluster anions. 11 Fe-PAH complexes were studied theoretically by Senapati et al, 61 Wang et al, 50 and Simon and Joblin.…”