The reactions of laser-ablated B atoms with acetonitrile in 4 K solid neon have been investigated by matrixisolation infrared spectra, and new products have been identified by 10 B, D, and 13 C isotopic substitutions and quantum chemical calculations. The side-on complex B-η 2 -(NC)-CH 3 was observed during deposition and isomerized to NCBCH 3 , CNBCH 3 , and CNB(H)�CH 2 , respectively, through C−C bond breakage and hydrogen transfer. For diboron reaction with acetonitrile, the Nend-on complex BBNCCH 3 was formed on deposition, which rearranged to HBNC(B)�CH 2 and HBNBC�CH 2 by λ > 220 nm irradiation. In this reaction pathway, the C�N triple bond was completely cleaved. The final diboron product HBNBC�CH 2 was much more stable than the precursors by 152.0 kcal mol −1 at the CCSD(T)-Full/cc-pVTZ//B3LYP/aug-cc-pVTZ level of theory.

The reaction of MnH2 with CO2 gave insertion product HMn(η2-O2CH) by concerted hydride ion transfer.

The reactions of laser-ablated Ce, Sm, Eu, and Lu atoms with acetonitrile were studied by matrix infrared spectra in a neon matrix, and M← NCCH 3 , M-η 2 -(NC)−CH 3 , and CN−M−CH 3 were identified with isotopic substitution and quantum chemical calculations. The major product is the insertion complex (CN−M−CH 3 ), while the end-on and side-on complexes (M←NCCH 3 and M-η 2 -(NC)−CH 3 ) are also trapped in the matrix. The CCN antisymmetric stretching mode for Ce-η 2 -(NC)−CH 3 was observed at 1536.9 cm −1 , which is much lower than the same modes observed for other lanthanides. NBO analysis reveals that Ce exhibits a remarkable 4f-orbital contribution in bonding to N and to C, reconfirming an active 4f-orbital contribution of cerium in bonding in the side-on complex, while the 4f contributions of Sm and Eu to the M−N and M−C bonds are much lower and the 4f orbital of Lu is not involved in bonding.

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