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Hydrogen-bonded H‚‚‚π complexes of C 2 H 2 and C 2 H 4 were studied both computationally and experimentally. Computationally, C 2 H 2-C 2 H 4 clusters ranging from 1:1 to 6:1 stoichiometries were identified. Using matrix isolation infrared spectroscopy, the 1:1 adduct was studied in an argon matrix. Formation of these adducts was evidenced by shifts in the vibrational frequencies of the acetylene and ethylene submolecules in the complex. The molecular structure, vibrational frequencies, and stabilization energies of the complexes were calculated at the HF, MP2, MP2(full), and B3LYP levels of theory by employing basis sets ranging from 6-31G(d,p) to 6-311++G(2d,2p). Both computations and experiments showed that two types of complexes are formed, one in which acetylene acts as a proton donor to the π cloud of ethylene and another in which ethylene acts as the proton donor to the π cloud of acetylene. Structures, interaction energies, and vibrational frequencies have also been obtained for 1:2, 1:4, and 1:6 complexes of ethylene and acetylene. This work presents a case study of hydrogen-bonded clusters formed through the H-π interaction.

Matrix-isolation infrared spectra of trimethyl phosphate (TMP), triethyl phosphate (TEP), and tri- n-butyl phosphate (TBP), in argon and nitrogen matrices, are reported for the first time. The peak widths of the sharpest features in our matrix-isolated spectra are typically 2 cm−1, compared with peak widths of 40 cm−1 seen in liquids for these compounds. Comparison with the vapor-phase spectrum of TMP reported earlier indicates that TMP is trapped in two different conformations in these matrices. Similar spectra were also obtained for TEP. Our matrix-isolated spectra indicate that the intramolecular hydrogen bonding (which is believed to be responsible for the lowering of the P=O frequency in the C3, conformer relative to the C3 conformer in these compounds) is stronger in TEP than in TMP. In the case of TBP, the peak widths were larger (8–10 cm−1) than those obtained for TMP and TEP. This observation is probably due to a distribution of conformers that may be trapped in the matrix, as a result of the increased alkyl chain length in TBP.

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Uranium oxide was laser-ablated using the second harmonic of a Nd : YAG laser, and the products studied after trapping them in Ar and Nz matrices. The species obtained in the Ar matrix were UO, UO2 and UO3, which represent the primary products of laser ablation. Charge transfer complexes, (UO~) (O]) and (UO 2+) (022-) were also observed. In the N 2 matrix, in addition to the primary ablation products, reaction products with nitrogen were also observed; the prominent among them being UN2 and NUO, together with their complexes with N2. Charge transfer complexes were also seen in these experiments. Features due to NO, N3 and N] were identified, which clearly point to the role of nitrogen in these reactions•