Matrix Infrared Spectra and Theoretical Calculations of Fluoroboryl Complexes F2B–MF (M = C, Si, Ge, Sn and Pb)

F2BMF (M = B and Al) Molecules: A Matrix Infrared Spectra and Theoretical Calculations Investigation

Reactions of laser-ablated B and Al atoms with BF₃ have been explored in the 4 K excess neon through the matrix isolation infrared spectrum, isotopic substitutions and quantum chemical calculations. The inserted complexes F₂BMF (M = B, Al) were identified by anti-symmetric and symmetric stretching modes of F-B-F, and the F-¹¹B-F stretch modes are at 1336.9 and 1202.4 cm^-1 for F₂¹¹B¹¹BF and at 1281.5 and 1180.8 cm^-1 for F₂¹¹BAlF. The CASSCF analysis, EDA-NOCV calculation and the theory of atoms-in-molecules (AIM) are applied to investigate the bonding characters of F₂BBF and F₂BAlF molecules. The bonding difference between boron and aluminum complexes reveals interesting chemistries, and the FB species stabilization by a main group atom was first observed in this article.

F2BMF (M = V, Nb, and Ta) and FBMF2 (M = Nb and Ta): A Combined Matrix Isolation Infrared Spectroscopic and Quantum Chemical Investigation

Through matrix isolation infrared spectrometry and quantum chemical calculations, the reactions of laser ablated V, Nb, and Ta with boron trifluoride were investigated in excess solid neon at 4 K. The possible reaction products FBMF₂, F₂BMF, and BMF₃ (M = V, Nb, and Ta) were calculated at the B3LYP, BPW91, and CCSD(T) levels of theory. The B-M bond strength in FBMF₂ molecules is confirmed by energy decomposition analysis-natural orbitals for chemical valence calculations, CASSCF calculation, and natural bond orbital analysis, which favors one σ bond and two half π bonds.

Matrix infrared spectroscopy of F2BMF and FB[triple bond, length as m-dash]WF2 (M = Cr, Mo and W) complexes and quantum chemistry calculations

Laser-ablated group 6 transition metal atoms react with BF3 to yield typical transition metal inserted complexes F2B-MF (M = Cr, Mo, and W) and terminal borylene complex FB[triple bond, length as m-dash]WF2. These products are investigated by using infrared spectroscopy, isotopic substitution and theoretical frequency calculations. The inserted complexes F2B-MF (M = Cr, Mo, and W) were identified by antisymmetric and symmetric stretching modes of F-B-F. The FB[triple bond, length as m-dash]WF2 molecule has a 11B-F (10B-F) stretching frequency at 1453.2 (1505.0) cm-1 and the triple bond between boron and tungsten is confirmed by EDA-NOCV calculations, CASSCF calculation and NBO analysis. Furthermore, the bonding for tungsten complexes is compared with that of molybdenum and chromium complexes, which reveals interesting differences in their chemistries.

Boron-Transition-Metal Triple-Bond FB≡MF2 Complexes

The boron-transition-metal triple-bond complexes FB≡MF₂ (M= Ir, Os, Re, W, Ta) were trapped in excess solid neon and argon through metal atom reactions with boron trifluoride and identified by matrix isolation infrared spectroscopy and quantum chemical calculations. The FB≡MF₂ molecule features very high ¹¹B-F stretching frequencies at 1586.6 cm^-1 (Ir), 1526.6 cm^-1 (Os), 1505.5 cm^-1 (Re), and 1453.2 cm^-1 (W), respectively. The very high strength of B≡M bonds with triple-bonding character is confirmed by EDA-NOCV calculations and the active molecular orbital and NBO analysis. The experimental observation of FB stabilization by heavy transition-metal atoms with triple bonds opens the door to design new boron-transition-metal complexes.