Magnesium-stabilised transition metal formyl complexes: structures, bonding, and ethenediolate formation

Abstract

Herein we report the first comprehensive series of crystallographically characterised transition metal formyl complexes. In these complexes, the formyl ligand is trapped as part of a chelating structure between a...

Carbon–Carbon Bond Formation from CO and H– The Role of Metal Formyl Intermediates

“…[22][23][24][25] The first structurally characterised formyl complex, [ReCp(CHO)(NO)(PPh 3 )], was reported by Gladysz and coworkers in 1979. [26] We [21] and others [27] have shown that the formyl ligand can be stabilised through resonance with the corresponding oxycarbene structure (Figure 1). [28] Figure 1.…”

“…We recently reported reaction of magnesium hydride dimer 28 with a series of metal carbonyl complexes (M = Cr, Mn, Fe, Co, Rh, W, Ir). [21] In all cases, transition metal formyl complexes…”

“…[8,20] Despite their importance, the detailed study of transition metal formyl complexes has been hampered by their low stability. [21] Early studies established that these species undergo facile -elimination to form the corresponding metal-hydrido carbonyl complex. This reaction is potentially reversible, though in most cases the hydrido-carbonyl is thermodynamically favoured.…”

“…In our study on ethenediolate formation at Cr---Mg complexes, DFT calculations suggest that direct dimerisation of a putative bis(formyl) intermediate ( 62) is a high energy process (G° > 50 kcalmol -1 ), strongly suggesting that this mechanism is not in operation (Scheme 12b). [21] Scheme 12. Reported DFT calculated pathways with (bis)formyl dimerisation mechanism for ethenediolate formation.…”

Carbon‐Carbon Bond Formation from Carbon Monoxide and Hydride: The Role of Metal Formyl Intermediates**

“…In our study on ethenediolate formation at Cr-Mg complexes, DFT calculations suggest that direct dimerisation of a putative bis(formyl) intermediate ( 62) is a high energy process (ΔG°> 50 kcal mol À 1 ), strongly suggesting that this mechanism is not in operation (Scheme 12b). [23]…”