Metal-formaldehyde chemistry: metal-promoted elementary transformations of formaldehyde

Gas‐Phase Reactivity of Metavanadate [VO3]− towards Methanol and Ethanol: Experiment and Theory

“…[59][60][61] Such complexes are relevant to the catalytic reduction of carbon monoxide, for which coordinated h 2 -O,C-OCH 2 ligands are possible intermediates. [54,56,58] The present work demonstrates the formation of a h 2 -O,C-OCH 2 ligand at a vanadium centre by hydrogen-atom transfer from a methoxo ligand.…”

“…[54] For example, the complex Cp 2 V(h 2 -O,C-OCH 2 ) (Cp: h 5 -C 5 H 5 ) was prepared by reaction of paraformaldehyde with vanadocene Cp 2 V. [55,56] Equivalent ligands have been observed for the heavier congeners niobium and tantalum, [57,58] as well as for siloxide-supported centres, for example, [(tBu 3 SiO) 3 Ta(h 2 -O,C-OCH 2 )]. [59][60][61] Such complexes are relevant to the catalytic reduction of carbon monoxide, for which coordinated h 2 -O,C-OCH 2 ligands are possible intermediates.…”

Low-Valent Titanium-Mediated Reductive Coupling of Carbonyl Compounds

“…Low-valent titanium compounds are generally less efficient in McMurry coupling reaction than in pinacol coupling reaction. The Ti(II) compound Cp 2 Ti(CO) 2 was shown to promote coupling of aromatic aldehydes to form 1,2-diols [112] and alkenes while the Ti(III) complex CpTiCl 2 (THF) 1.5 reacted with CH 2 O to produce CH 2 =CH 2 and (CpTiCl 2 ) 2 O [113]. The zerovalent titanium complex (η 6 -C 6 H 6 ) 2 Ti has been found to be highly active in McMurry coupling of both aliphatic and aromatic ketones to yield alkenes [114]; 1,2-diols were never detected in reactions mediated by (η 6 -C 6 H 6 ) 2 Ti.…”

The McMurry Coupling and Related Reactions

“…Low-valent organotitanium complexes are generally much less successful in the alkene-forming coupling of carbonyl compounds than in the McMurry pinacol reaction. Aromatic aldehydes have been coupled to form pinacols and alkenes by the Ti(II) compound Cp 2 Ti(CO) 2 [253], while reaction of paraformaldehyde with the Ti(III) complex CpTiCl 2 (THF) 1:5 afforded ethylene and the oxide (CpTiCl 2 ) 2 O [254]. The titanium(0) complex (h-C 6 H 6 ) 2 Ti was found to be highly active in the reductive coupling of both aromatic and aliphatic ketones, and no pinacols were ever obtained in these reactions; furthermore, the reactions of pinacols with this compound were much slower than the reactions of ketones [255].…”