Reactivity Studies of [(thf)<sub>2</sub>Mg{μ-C(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>C(CH<sub>3</sub>)<sub>2</sub>}]<sub>2</sub>: Scrambling Reactions and Diverse Reactions with Dichlorophenylphosphane

In THF solution [{(thf)<sub>2</sub>Mg­{μ-C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>C}}<sub>2</sub>] (<b>1</b>) exchanges the alkanediide ligand with [{(thf)<sub>2</sub>Mg­{μ-CH<sub>2</sub>)<sub>5</sub>}}<sub>2</sub>] in an equilibrium leading to the formation of [{(thf)<sub>2</sub>Mg}<sub>2</sub>{μ-C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>C­(CH<sub>3</sub>)<sub>2</sub>}­{μ-(CH<sub>2</sub>)<sub>5</sub>}] (<b>2</b>). Depending on the crystallization temperature, homoleptic <b>1</b> or heteroleptic <b>2</b> crystallizes from THF solutions, verifying a temperature-dependent Schlenk equilibrium. Irradiation of a solution of <b>1</b> in [D<sub>8</sub>]­THF with UV light yields magnesium hydride and alkene via a β-hydride elimination reaction. In a metathetical approach dichlorophenylphosphane reacts with <b>1</b> in THF to give the intermediate “PhP­(Cl)­{C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>CMgCl” (<b>3-MgCl</b>), which forms three subsequent products. In order to ease handling and characterization of these compounds, hydrolysis and oxidation with sulfur has been performed. This product mixture was separated by column chromatography, yielding the chlorophosphane sulfide [Ph­(S)­P­(Cl)­{C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>CH)}] (<b>3-S</b>), the cyclic phosphane sulfide [Ph­(S)­P­{C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>C)}] (<b>4-S</b>), and the cyclic 1,1-diphosphane disulfide [{(Ph­(S)­P}<sub>2</sub>{μ-C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>C}] (<b>6-S<sub>2</sub></b>). Furthermore, traces of the acyclic 1,1-diphosphane disulfides [{PhP­(S)­(C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>CH­(CH<sub>3</sub>)<sub>2</sub>)}­{PhP­(S)­(C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>C­(CH<sub>3</sub>)­(CH<sub>2</sub>)}] (<b>8-S<sub>2</sub></b>) and <i>meso</i>-[{Ph­(S)­P­(C­(CH<sub>3</sub>)<sub>2</sub>C<sub>2</sub>H<sub>4</sub>(CH<sub>3</sub>)<sub>2</sub>CH)}<sub>2</sub>] (<b>7-S<sub>2</sub></b>) have also been isolated. Compounds <b>6</b>–<b>8</b> represent the phosphorus-containing products of indirect Grignard reductions.