Vibrational Spectroscopy of Ni⁺(benzene)_n Complexes in the Gas Phase

Abstract

Ni+ (benzene)n (n = 1-6) and Ni+ (benzene)n Ar(1,2) (n = 1,2) are produced by laser vaporization in a pulsed nozzle cluster source. The clusters are mass selected and studied by infrared laser photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer. The excitation laser is an OPO/OPA system that produces tunable IR in the C-H stretching region of benzene. Photodissociation of Ni+ (benzene)n complexes occurs by the elimination of intact neutral benzene molecules, while Ni+ (benzene)n Ar(1,2) complexes lose Ar. This process is enhanced on resonances, and the vibrational spectrum is obtained by monitoring the fragment yield versus the infrared wavelength. Vibrational bands in the 2700-3300 cm(-1) region are characteristic of the benzene molecular moiety with systematic shifts caused by the metal bonding. A dramatic change in the IR spectrum is seen at n = 3 and is attributed to the presence of external benzene molecules acting as solvent molecules in the cluster. The results of previous theoretical calculations are employed to investigate the structures, energetics, and vibrational frequencies of these complexes. The mono-benzene complex is found to have a C2v structure, with benzene distorted by the metal pi-bonding. The di-benzene complex is found to have a D2h structure, with both benzenes distorted. The comparison between experiment and theory provides intriguing new insight into the bonding in these prototypical pi-bonded organometallic complexes.

Vibrational spectra of discrete UO22+ halide complexes in the gas phase

“…Using electrospray uranyl halide coordination complexes can be generated [12] and then trapped in a Fourier transform ion cyclotron resonance mass spectrometer, where they can be isolated and then photodissociated using light from a free electron laser (FEL) in the mid-IR [13][14][15], or from an optical parametric oscillator laser tuned to higher frequencies corresponding to H-stretching regions [16][17][18][19][20][21][22][23][24]. In the mid-IR region of the spectrum, photons are not sufficiently energetic to cause dissociation needed to observe vibrational fundamentals.…”

The Phenoxy/Phenol/Copper Cation: A Minimalistic Model of Bonding Relations in Active Centers of Mononuclear Copper Enzymes

“…[51] Such a situation results in a dynamic equilibrium between all p-bound structures, which can be termed as a "copper ring-walk" in analogy to the well-known "hydrogen ringwalk" reported for protonated aromatic compounds. [52][53][54][55] In contrast, interaction of the copper ion with the oxygen atom of phenol leads to the least stable structure (1 d) of the [Cu- …”

General trends in dissociations of medium-sized hydrocarbon dications

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