Reductive Metallation of Dendralenes and Myrcene Using Dimagnesium(I) Compounds: A Facile Route to Unsaturated Organomagnesium Compounds.

The two-electron reduction of 2,3-dimethylbuta-1,3-diene (DMB) with β-diketiminate and guanidinate substituted dimagnesium(I) compounds has given complexes in which two bidentate amido-magnesium fragments are bridged through the π-system of the DMB dianion, viz. [(LMg) (μ-DMB)] (L= Nacnac, [HC(MeCNXyl) ] , Xyl=2,6-xylyl; or Priso=[(DipN) CNPr ] , Dip=2,6-diisopropylphenyl). Similar double reductions of [4]dendralene (4dend) have afforded the complexes, [(LMg) (μ-4dend)] (L= Nacnac, Ar=Xyl or mesityl (Mes); or Priso) in which the 4dend dianion is π-coordinated to the bidentate amido-magnesium fragments.

Molybdenum carbonyl assisted reductive tetramerization of CO by activated magnesium(i) compounds: squarate dianion metallo-ketene formation.

Reactions of a dimagnesium(i) compound, [{(Nacnac)Mg}] (Nacnac = [HC(MeCNDip)], Dip = 2,6-diisopropylphenyl), pre-activated by coordination with simple Lewis bases (4-dimethylaminopyridine, DMAP; or TMC, :C(MeNCMe)), with 1 atmosphere of CO in the presence of one equivalent of Mo(CO) at room temperature, led to the reductive tetramerisation of the diatomic molecule. When the reactions were carried out at room temperature, there is an apparent competition between the formation of magnesium squarate, [{(Nacnac)Mg}{-(κ-CO)}{μ-Mg(Nacnac)}], and magnesium metallo-ketene products, [{(Nacnac)Mg}[μ-O[double bond, length as m-dash]CC{Mo(CO)}C(O)CO]{Mg(D)(Nacnac)}], which are not inter-convertible. Repeating the reactions at 80 °C led to the selective formation of the magnesium squarate, implying that this is the thermodynamic product.

C-H Activation of Inert Arenes using a Photochemically Activated Guanidinato-Magnesium(I) Compound.

UV irradiation of solutions of a guanidinate coordinated dimagnesium(I) compound, [{(Priso)Mg} ] 3 (Priso=[(DipN) CNPr ] , Dip=2,6-diisopropylphenyl), in either benzene, toluene, the three isomers of xylene, or mesitylene, leads to facile activation of an aromatic C-H bond of the solvent in all cases, and formation of aryl/hydride bridged magnesium(II) products, [{(Priso)Mg} (μ-H)(μ-Ar)] 4-9. In contrast to similar reactions reported for β-diketiminate coordinated counterparts of 3, these C-H activations proceed with little regioselectivity, though they are considerably faster. Reaction of 3 with an excess of the pyridine, p-NC H Bu (py ), gave [(Priso)Mg(py H)(py ) ] 10, presumably via reduction of the pyridine to yield a radical intermediate, [(Priso)Mg(py ⋅)(py ) ] 11, which then abstracts a proton from the reaction solvent or a reactant.