EPR spectra of aluminum dicarbonyl in hydrocarbon matrixes

CO-Induced Dinitrogen Fixation and Cleavage Mediated by Boron

The boron atoms react with carbon monoxide and dinitrogen forming the end-on bonded NNBCO complex in solid neon or in nitrogen matrices. The NNBCO complex rearranges to the (η2 -N2 )BCO isomer with a more activated side-on bonded dinitrogen ligand upon visible light excitation. (η2 -N2 )BCO and its weakly CO-coordinated complexes further isomerize to the NBNCO and B(NCO)2 molecules with N-N bond being completely cleaved under UV light irradiation. The geometries, energies and vibrational spectra of the molecules are calculated with quantum chemical methods and the electronic structures are analyzed with charge- and energy-partitioning methods.

Electron Paramagnetic Resonance Study of the Mononuclear Al Species Formed in the Reaction of Al Atoms and Cyclopropylamine at 77 K in an Adamantane Matrix

Ground-state Al atoms have been reacted with cyclopropylamine (CpNH2) in an adamantane matrix at 77 K. The four paramagnetic species generated in the reaction have been studied by electron paramagnetic resonance (EPR) spectroscopy and their magnetic parameters extracted from the EPR spectra. The isotropic Al hyperfine interactions (hfis) for these radicals vary from 801 to 962 MHz and are consistent with values previously reported for structurally similar Al-centered radicals. The major species formed in the reaction has a highly anisotropic a tensor indicative of an Al-centered radical with a substantial amount of the unpaired spin density residing in the Al 3p orbital. In addition, there is EPR evidence that the insertion products, CpNH(AlH) and CpAlNH2, are formed in the reaction, suggesting that Al atoms can activate the N-H and C-N bonds of amines. It has been shown that a molecule of CpNH2 coordinates to CpNH(AlH), causing the Al, N and H hfi of the N-H insertion product to decrease. The values of the nuclear hfis calculated for the insertion products, using a density functional theory (DFT) method, are comparable to the experimental values.

C?C Double- and Triple-Bond Formation from Reactions of B Atoms with CO: Experimental and Theoretical Characterization of OBBCCO and OBCCBO Molecules in Solid Argon

Reactions of boron atoms with CO molecules in solid argon form the following boron carbonyl species (which have been reported earlier): BCO, BBCO, OCBBCO, B(CO)2, and B4(CO)2. The OCBBCO molecule underwent a photochemical rearrangement where CO was activated to form the OBBCCO and OBCCBO molecules. The new molecules were identified on the basis of isotopic IR studies with 10B, 11B, 13C16O, 12C18O, and carbon dioxide mixtures in addition to comparison with quantum-chemical calculations of isotopic frequencies. Theoretical analyses showed that the OBBCCO and OBCCBO molecules are linear with C-C double and triple bonding, respectively, and lie at a much lower energy than the linear OCBBCO structure.