Complex with Linear B-B-B Skeleton Trapped in Dinitrogen Matrix: Matrix Infrared Spectra and Quantum Chemical
Juanjuan Cheng1, Liyan Cai1, Fei Cong1
1School of Chemical Science and Engineering, Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092, China.
Abstract:
The neutral (NN)-B-B-B-(N2) complex has been trapped in low-temperature dinitrogen matrix and identified by isotopic substitution and theoretical frequency calculations. The linear B-B-B skeleton is stabilized by two inequivalent N2, namely, one end-on and other side-on N2. The structure of linear B-B-B skeleton illustrates much difference from previously reported triangle configuration of B3 clusters. Frontier orbital analysis demonstrates that the σ orbital of end-on NN and the π-bonding orbital of side-on N2 acts as the donor orbital. π bonding character across B-B-B skeleton donates to the antibonding π* orbital of end-on NN and out of phase the B-B-B features π back-donation to antibonding π* orbital of side-on N2. The combination of strong σ-donating capacity coupled with a greater ability for accepting π-back-donation of the N2 ligand leads to the formation of (NN)-B-B-B-(N2) complex with linear B-B-B skeleton. In addition, complexes of (NN)B(NN), (NN)BB(NN), and (NN)B4(NN) have been identified in our experiments.
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