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The reaction of atomic boron with benzene in solid neon has been investigated by matrix isolation infrared spectroscopy with isotopic substitutions as well as quantum chemical calculations. The reaction is initiated by boron atom addition to benzene in forming an η2-(1, 4) π adduct (A). A borepinyl radical (B) formed by C-C bond insertion is also observed on annealing. The η2-(1,4) π adduct photoisomerizes to an unprecedented borole substituted vinyl radical intermediate (C) via ring-opening and rearrangement reactions involving an antiaromatic borole subunit. A previously unconsidered 1-ethynyl-2-dihydro-1H-borole radical (D) is generated as the final product under UV light irradiation. The results presented herein give new insight into the benzene carbon-carbon bond cleavage and rearrangement reactions mediated by a nonmetal and provide a possible route for the construction of heterocyclic borepinyl and borole species via benzene ring opening and rearrangement reactions.

The following gas-phase uranyl/12-crown-4 (12C4) complexes were synthesized by electrospray ionization: [UO2(12C4)2]2+ and [UO2(12C4)2(OH)]+. Collision-induced dissociation (CID) of the dication resulted in [UO2(12C4-H)]+ (12C4-H is a 12C4 that has lost one H), which spontaneously adds water to yield [UO2(12C4-H)(H2O)]+. The latter has the same composition as complex [UO2(12C4)(OH)]+ produced by CID of [UO2(12C4)2(OH)]+ but exhibits different reactivity with water. The postulated structures as isomeric [UO2(12C4-H)(H2O)]+ and [UO2(12C4)(OH)]+ were confirmed by comparison of infrared multiphoton dissociation (IRMPD) spectra with computed spectra. The structure of [UO2(12C4-H)]+ corresponds to cleavage of a C–O bond in the 12C4 ring, with formation of a discrete U–Oeq bond and equatorial coordination by three intact ether moieties. Comparison of IRMPD and computed IR spectra furthermore enabled assignment of the structures of the other complexes. Theoretical studies of the chemical bonding features of the complexes provide an understanding of their stabilities and reactivities. The results reveal bonding and structures of the uranyl/12C4 complexes and demonstrate the synthesis and identification of two different isomers of gas-phase uranyl coordination complexes.

A ground-state boron atom inserts into the C=C bond of ethylene to spontaneously form the allene-like compound H2 CBCH2 on annealing in solid neon. This compound can further isomerize to the propyne-like HCBCH3 isomer under UV light excitation. The observation of this unique spontaneous C=C bond insertion reaction is consistent with theoretical predictions that the reaction is thermodynamically exothermic and kinetically facile. This work demonstrates that the stronger C=C bond, rather than the less inert C-H bond, can be broken to form organoboron species from the reaction of a boron atom with ethylene even at cryogenic temperatures.

The reactions of early lanthanide metal atoms (Ce, Pr, and Nd) with carbon monoxide and nitric oxide mixtures are studied by infrared absorption spectroscopy in solid argon. The reaction intermediates and products are identified via isotopic substitution as well as theoretical frequency calculations. The results show that the reactions proceed with the initial formation of inserted NLnO molecules, which subsequently react with CO to form the NLnO(CO) complexes on annealing. The NLnO(CO) complexes further isomerize to the more stable isocyanate OLnNCO species under UV light excitation.

A combined experimental and theoretical study on the main-group tricarbonyls [B(CO)3 ] in solid noble-gas matrices and [C(CO)3 ](+) in the gas phase is presented. The molecules are identified by comparing the experimental and theoretical IR spectra and the vibrational shifts of nuclear isotopes. Quantum chemical ab initio studies suggest that the two isoelectronic species possess a tilted η(1) (μ1 -CO)-bonded carbonyl ligand, which serves as an unprecedented one-electron donor ligand. Thus, the central atoms in both complexes still retain an 8-electron configuration. A thorough analysis of the bonding situation gives quantitative information about the donor and acceptor properties of the different carbonyl ligands. The linearly bonded CO ligands are classical two-electron donors that display classical σ-donation and π-back-donation following the Dewar-Chatt-Duncanson model. The tilted CO ligand is a formal one-electron donor that is bonded by σ-donation and π-back-donation that involves the singly occupied orbital of the radical fragments [B(CO)2 ] and [C(CO)2 ](+) .

The infrared spectra of mass-selected Ni(O2)n(+) (n = 2-4) and their argon-tagged complexes are measured by infrared photodissociation spectroscopy in the gas phase. The experimental spectra provide distinctive patterns allowing the determination of their geometric and electronic structures by comparison with the simulated vibrational spectra from density functional theory calculations. The [Ni(O2)2Ar2](+) cation complex was determined to have D2h symmetry involving a Ni(O2)2(+) core ion with two equivalent superoxide ligands side-on bound to a Ni(3+) cation center. The higher Ni(O2)3(+) and Ni(O2)4(+) cation complexes were determined to have structures with a chemically bound Ni(O2)2(+) core ion that is weakly coordinated by neutral O2 molecule(s).

Infrared spectra of mass-selected oxygen-rich iron dioxygen complexes Fe(O2)n(+) with n = 3-5 are measured via infrared photodissociation spectroscopy in the gas phase. These cation complexes are produced via a laser vaporization supersonic ion source. The structures are established by comparison of the experimental spectra with the simulated spectra derived from density functional calculations. All of the Fe(O2)n(+) complexes studied have a single IR-active band in the 1050-1100 cm(-1) region, arising from the O-O stretching vibration of the superoxo ligand(s). These complexes are determined to have structures with a chemically bound Fe(O2)2(+) core ion that is weakly coordinated by neutral O2 molecules. The Fe(O2)2(+) core ion has a planar D2h symmetry with two equivalent side-on superoxo ligands bound to an Fe(3+) cation center.