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.