Reactions of Laser-Ablated Aluminum Atoms with Cyanogen: Matrix Infrared Spectra and Electronic Structure Calculations for Aluminum Isocyanides Al(NC)1,2,3 and Their Novel Dimers

Laser-ablated Al atoms react with (CN)(2) in excess argon during condensation at 4 K to produce AlNC, Al(NC)(2), and Al(NC)(3), which were computed (B3LYP) to be 27, 16, and 28 kJ/mol lower in energy, respectively, than their cyanide counterparts. Irradiation at 220-580 nm increased absorptions for the above molecules and the very stable Al(NC)(4)(-) anion. Annealing to 30, 35, and 40 K allowed for diffusion and reaction of trapped species and produced new bands for the Al(NC)(1,2,3) dimers including a rhombic ring core (C)(AlN)(2)(C) with C's attached to the N's, a (NC)(2)Al(II)-Al(II)(NC)(2) dimer with a computed Al-Al length of 2.557 angstrom, and the dibridged Al-2(NC)(6) molecule with a calculated D-2h structure and rhombic ring core like Al2H6. In contrast, the Al(NC)(4)(-) anion was destroyed on annealing presumably due to neutralization by Al+. B3LYP calculations also show that aluminum chlorides form the analogous molecules and dimers. In our search for possible new products, we calculated Al(NC)(4) and found it to be a stable molecule, but it was not detected here.