Laser Plasma Production of Metal and Metal Compound Complexes with Polycyclic Aromatic Hydrocarbons

Abstract

Gas-phase complexes of metals and/or metal compounds with polycyclic aromatic hydrocarbons (PAHs) are produced by covaporization of materials in a laser plasma source and detected using a time-of-flight mass spectrometer. Mixtures of metal powder, metal salts, metal oxides, or other materials with the PAH of interest are ablated and ionized with a pulsed Nd:YAG laser. Mass spectroscopy reveals that transition and rare earth metals efficiently produce both monoligand and sandwich complexes of the form M+(PAH) x , with x = 1, 2. Surprisingly, both iron and cobalt resist the formation of complexes when pure metal powder is employed, but produce them efficiently when salts, oxides, or organometallics are employed. Covaporization of the organometallic-π complexes iron cyclopentadienyl and dibenzene chromium with PAHs yields both homoligand and heteroligand complexes. Transition metal oxides and chlorides produce monoligand complexes exclusively. In contrast, rare earth oxides produce both monoligand and sandwich complexes, presumably due to the increased ionic radius of the metal center.

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

“…1͒. The TM atoms/ions have 6 -binding, 3 -binding, and 2 -binding sites available on both of these carbon rings of pyrene.…”

“…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.…”

Photoelectron spectroscopic study of iron-pyrene cluster anions

“…Transition metal-organic molecular complexes play an important role in the field of organometallic chemistry because of their unique structural, electronic and magnetic properties. Many experimental and theoretical studies have provided information regarding the interactions between various transition metals and organic ligands, such as benzene, pyridine, 22 fullerene (C 60 ), 6,15,[23][24][25][26][27][28][29][30][31] coronene, 15,[32][33][34][35][36][37][38][39][40][41][42] cyclooctatetrene (COT), 6,43,44 and pyrene. 37,45,46,49 Most of these studies have focused on characterizing the bonding between the d-electrons in the subject transition metals and the πelectrons of the organic ligands.…”

“…48 Dunbar and coworkers 32 generated the complexes of Sc + , Mn + , and several other metals with one or more coronene molecules. Duncan and co-workers, 15,[33][34][35][36][37][38][39] reported photodissociation studies of Sc(coronene) 1,2…”

Laser Plasma Production of Metal−Corannulene Ion−Molecule Complexes

“…New techniques for metal vapor production and ligand aggregation schemes have made it possible to produce a fascinating variety of metal−aromatic complexes in the gas phase . Clusters and complexes synthesized in these environments include metal−polycyclic aromatic hydrocarbon (PAH) complexes, − metal−fullerene complexes, − multimetal atom-coated fullerenes, − and transition metal−aromatic multidecker sandwiches. − Although numerous examples of metal−aromatic complexes have been described, there is still much to learn about the structure and bonding of these systems. Recent work in our group has focused on new strategies for the production of metal−PAH complexes and the trends in complex growth and metal−aromatic bonding behavior .…”