Reaction of CO₂ with a Vanadium(II) Aryl Oxide: Synergistic Activation of CO₂/Oxo Groups towards H‐Atom Radical Abstraction

Abstract

Treatment of divalent (ONNO)V(TMEDA) (1; ONNO=[2,4-Me -2-(OH)C H CH ] N(CH ) NMe ) with CO afforded [(ONNO)V] (μ-OH)(μ-formate) (2). Whereas the bridging hydroxo and formate groups both originated from CO , the H atoms present on the two residues were obtained through H-atom radical abstraction from the solvent. DFT calculations revealed an initially linear CO bonding mode, followed by deoxygenation, and highlighted a synergistic effect between the so-formed oxo group and an additional bridging CO residue in promoting radical behavior.

Linear End‐On Coordination Modes of CO2

“…[6] This leaves us with the only possibility that the initial deoxygenation is carried out by cooperative one-electron attack of two divalent vanadium centers on the same CO 2 molecule,r eleasing CO 11, O5-V1-N1 = 174.57 (12) and O4-V1-O3 = 174.59-(10). [31] (6) and V1-O4-V2 = 100.31(6). [31] Angewandte Chemie Communications and affording at rivalent oxo-bridged vanadium complex.…”

Linear End‐On Coordination Modes of CO2

“…[1][2][3][4][5][6] Besides the well-established reactions with strong nucleophiles (for example,a lkyls,a mides,a nd hydrides) which always resolve in addition-insertion reactions,t he chemical behavior of this exceedingly stable molecule mainly consists of redox transformations. [1][2][3][4][5][6][7][8][9][10][11][12] Thee arly work of Floriani four decades ago has indicated that while at woelectron attack (either cooperative interaction from two metals or monometallic) affords deoxygenation or disproportionation, one-electron donation may allow valuable CÀC forming reactions. [7][8][9][10][11]13] However, the fact that CO 2 requires fairly strong reducing agents makes the conversions within the C1-redox series (CO 2 ,f ormic acid, CO,f ormaldehyde, methanol, methane) generally difficult to control.…”

“…[7][8][9][10][11]13] However, the fact that CO 2 requires fairly strong reducing agents makes the conversions within the C1-redox series (CO 2 ,f ormic acid, CO,f ormaldehyde, methanol, methane) generally difficult to control. [1,14] This is due to the fact that the key to determining the outcome of ar edox transformation is the ability to tune the extent of electron transfer, [5,6] implying that selective reactants need to be found.…”

“…To this end, CO 2 reduction was observed through an unusual radical hydrogen atom extraction from the reaction solvent. [6] In this work, we have isolated and characterized amononuclear CO 2 complex adding as econd example to the sole existing case of linear end-on bonding mode. [28] We further showed that such as pecies is linked to an unusual reactivity pattern and investigated further the reactivity of this rare bonding mode.W eh ave also isolated the first example of abridging end-on binuclear complex.…”

“…and radical Ha tom abstraction, required heating and moderate pressure of CO 2 (Scheme 1). [6] By instead carrying out the reaction at low temperatures and enabling sufficient time (À10 8 8C, 1atm) we have now isolated an ew species,( ONNO)V III (h 1 -OCO)(OH) (2), in analytically pure form and significant yield (Scheme 1). The GC trace of the headspace of the reaction vessel after 12 hof reaction clearly showed the presence of CO.C omplex 2 was obtained as ar ed crystalline material by slow diffusion of pentane.T he formula was yielded by its X-ray crystal structure ( Figure 1).…”