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Copper complexes of 2,2′-bipyridine (22BIPY) and 4,4′-bipyridine (44BIPY) were prepared in a laser-vaporization supersonic molecular beam source and identified by laser photoionization time-of-flight mass spectrometry. Electronic spectra and molecular structures were studied with pulsed-field ionization zero electron kinetic energy (ZEKE) electron spectroscopy, density functional theory (DFT) and second-order Møller-Plesset perturbation (MP2) calculations, and spectral simulations. Adiabatic ionization energies and metal-ligand and ligand-based vibrational frequencies of Cu-22BIPY and Cu-44BIPY were measured from the ZEKE spectra. Ground electronic states and molecular structures of the two complexes were determined by comparing the spectroscopic measurements with the theoretical calculations. The ground state of Cu-22BIPY (2B1, C2 v) has a planar bidentate structure with Cu binding to two nitrogen atoms and two pyridine molecules in the cis configuration. The ground state of Cu-44BIPY (2A, C2) has a monodentate structure with Cu binding to one nitrogen and two pyridines in a twisted configuration. The ionization energy of Cu-22BIPY is considerably lower and its bond energy is much higher than that of Cu-44BIPY. The different ionization and dissociation energies are attributed to the distinct metal binding modes of the two complexes. It has been found that the DFT calculations yield the correct structures for the Cu-22BIPY complex, whereas the MP2 calculations produce the best structures for the Cu-44BIPY complex. [ABSTRACT FROM AUTHOR]

This paper presents pulsed-field ionization, zero electron kinetic energy (ZEKE) photoelectron and threshold photoionization spectra of M-X(CH3)3 (M = Ga, In; X = P, As). The ZEKE spectra exhibit well-resolved vibrational structures. A comparison with B3LYP calculations shows that the spectrum of In-P(CH3)3 arises from the 1A1 ← 2E transition and the spectra of Ga-P(CH3)3 and Ga-As(CH3)3 arise from transitions of a Jahn–Teller distorted doublet state to the 1A1 state. The intensities of the 1A1–2E transition in the indium species are described with the Franck–Condon approximation, while the transitions in the gallium complexes are more complicated due to the dynamic Jahn–Teller effect. The adiabatic ionization potentials of Ga-P(CH3)3, In-P(CH3)3, and Ga-As(CH3)3 are 39 635, 38 930, and 40 322 cm–1, respectively, and the ionization threshold of In-As(CH3)3 is ~39 550 cm–1. The metal–ligand stretching frequencies are 143, 116, and 125 cm–1 for Ga+-P, In+-P, and Ga+-As, respectively, and 96 cm–1 for In-P. The intermolecular bending frequencies are 71, 65, and 42 cm–1 for Ga+-P-C, In+-P-C, and Ga+-As-C, respectively, and 47 cm–1 for In-P-C. In addition, ligand-based vibrational frequencies are determined for the CH3 wag, PC3 and AsC3 umbrella, and P-C stretching vibrations. [ABSTRACT FROM AUTHOR]